Copyright is owned by the Author of the thesis. Permission is given for a copy to be downloaded by an individual for the purpose of research and private study only. The thesis may not be reproduced elsewhere without the permission of the Author. A S TUDY OF P HYS I OLOGI CAL AND PRODUCTI VE D IFFERENCES BETWEEN FLEECE WEI GHT S ELECTED AND CONTROL ROMNEY S HEEP A t h e s i s p r e s ent ed i n par t i a l f u l f i l me nt o f t h e r e quireme nts f or the d eg r e e o f Doc t o r o f P h i l o s ophy i n An i ma l Sc i e nces a t Mass ey Un i ve r s i ty E) L . Anne McC l e l land 1 9 9 0 Hassey University Library. Thesis Copyright Form Title of thesis: of PHj?ibl,it:-itl tU!dp?PiucA?ve t:J_if&@lees fft.tt? Wti (; S e/uf.u{ a11t{ t!-H1f1-n (1) (a) AffFTI/Tlr.L.LA ?. I give permission for my .thesis to b made available to readers in the Massey University Library under conditions determined by the Librarian. (b) I do not ?ish my thesis to be made available to readers ?ithout my ?it ten consent for I 2- months. (2) (a) ? agree that my thesis, or a copy, may be sent to another institution under conditions determined by the Librarian. (b) I do not ?ish my thesis, or a copy, to be sent to another institution ?ithout my ?itten consent for /? months. (3) (a) (b) I agree that my thesis may be copied for Library use. I do not ?ish my thesis to be copied f.or Library use for J;l.. months. The copyright of this thesis belongs to the author . Readers must sign their name in the space below to show that they recognise this. They are asked to add their permanent address. NAME AND ADDRESS MASSEY UNIVERSIJ\1 LIBRARY DATE ACKNOWLEDGEMENTS Sincere thanks are extended to Dr . Hugh Blair for his patience during the supervison of this work and his support both in and out of academic circles . Dr . George Wickham is gratefully acknowledged for his supervision in Dr . Blair's absence and his unfaltering interest in the experimental subject . Prof . Rae also contributed many useful comments and I was particularly grateful for his suggestion of the infamous G-test , (Someday I will write a computer programme to do them and save my sanity) , even if I may not have appeared so at the time . Prof . Anderson is thanked for his support and encouragement in professional matters and his tolerance of animal breeders who digress from the biometrical to the biological . No remarks would be complete without thanking Dr . Stuart McCutcheon for his advice and criticisms , his witticisms , and his genuine interest in students . The departmental staff , especially , Merv and Merv , helped considerably to relieve the drudgery of endless midside samplings , washings etc.3etc . . The technical and support staff were always cheerful and supportive of "yet another mid-side sampler" who was voted "most likely to be late" every 28-days . Mr . Mark Carter , wherever he may be , was a real help in setting up computerized data recording and other "technological timesaving" . The staff of the APU are acknowledged for the care and maintenance of my experimental sheepies on weekends and throughout the course of my extended indoor trial . The graduate students in Animal Science formed an exciting and international group of friends . I thank them for helping me on rainy days of faecal samplings , endless days of washing wool samples , and for showing me the ropes of animal experimentation . I truly believe that I have never been as happy as I was during my time in Palmerston North . Special thanks are extended to Heather Meikle and Ewen Cameron. Heather was always willing to explain "wool things" to me and was a long lost friend come home. Ewen could kil l spiders. Coby Hoogendoorn is thanked for her assistance in doing the seasonal pasture cuts and for being just plain helpful. The other students in .nimal cience may be gone , but they are not forgotten. My time at Massey University was enriched through their acquaintance and I am grateful for my ever increasing world network of friends. The financial backing of Agriculture Canada's "Young Scientist Training Program" was greatly appreciated in allowing me to study and visit this beautiful country. I must also thank my parents for their support , if not understanding , of my pursuits. This thesis is dedicated to the loving memory of my mother , Gwen McClelland , who passed away before its completion. This one's for you Gwennie. i i i TABLE OF CONTENTS ACKNOWLEDGEMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i 1 . I NTRODUCT I ON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2 . 2 . 1 2 . 2 2 . 2 . 1 2 . 2 . 2 2 . 3 REVI EW OF L I TERATURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 . 3 . 1 2 . 3 . 2 L I VEWE I GHT AND I NTAKE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 WOOL GROWTH EFF I C I ENCY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Die t s e l e c tion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Diges tive a bility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 UTI L I SAT I ON OF AM I NO ACI DS FOR WOOL GROWTH . . . . . . . . . . . 7 S ulphur c o n t e n t o f wo o l . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Me tab o lism o f s u l phur -containing amino a cids . . . . . . . . . 8 3 . MATER I AL S AND METHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 3 . 1 DESCR I PT I ON OF THE EXPER I MENTAL FLOCKS AND THEI R MANAGEMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 3 . 2 ANALYT I CAL TECHN I QUES EMPLOYED . . . . . . . . . . . . . . . . . . . . . . 1 2 3 . 2 . 1 Data c o l l e c tion a nd c o r re c tio n . . . . . . . . . . . . . . . . . . . . . . 1 2 3 . 2 . 3 Te s t s o f a s sumptions in MANOVA . . . . . . . . . . . . . . . . . . . . . . 1 4 4 . 4 . 1 4 . 2 4 . 2 . 1 4 . 2 . 2 4 . 2 . 3 4 . 2 . 4 4 . 2 . 5 4 . 2 . 6 4 . 3 4 . 3 . 1 4 . 3 . 2 4 . 3 . 3 4 . 3 . 4 4 . 4 5 5 . 1 5 . 1 . 1 5 . 1 . 2 5 . 1 . 3 5 . 1 . 4 5 . 1 . 5 5 . 1 . 6 5 . 1 . 7 5 . 2 5 . 2 . 1 5 . 2 . 2 5 . 2 . 3 5 . 2 . 4 THE PERFORMANCE OF FW AND C RAM HOGGETS FED LUCERNE BASED D I ET S WI TH AND WI THOUT FORMALDEHYDE-PROTECTED PROTE I N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6 I NTRODUCT I ON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6 MATER I AL S AND METHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7 Experime nt a l p l a n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7 Feeding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 8 Wo o 1 gr owth r a t e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9 Liveweigh t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 0 Digestability o f DM and N . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1 Ana lytica l me t h ods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1 RESULTS AND D I S CUSS I ON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 3 Apparent diges tive ability . . . . . . . . . . . . . . . . . . . . . . . . . . 2 4 Liveweigh t and liveweight gain . . . . . . . . . . . . . . . . . . . . . . 2 5 Urine vo l ume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 6 W o o 1 g r o wt h . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 7 CONCLUS I ON S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1 S EASONAL I TY OF WOOL AND BODY GROWTH . . . . . . . . . . . . . . . . . . 3 2 I NTRODUCT I ON AND REVI EW OF L I TERATURE . . . . . . . . . . . . . . . 3 2 Nut rition a nd c limatic fact o r s . . . . . . . . . . . . . . . . . . . . . . 3 3 Hair and wo o l gr owth cyc l e s . . . . . . . . . . . . . . . . . . . . . . . . . 4 0 Ge ne tic dif f e r ences in r esponse t o s eason and nut ritiona l f act ors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 5 Hormona 1 e f f e cts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1 R o l e o f t h e Pinea l g land in wo o l g r owth cyc les . . . . . . 5 7 Meas uring t h e s easona lity o f wo o l g r owt h . . . . . . . . . . . . 6 3 S ummary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 6 MATERI AL S AND METHODS . . . . . . . . . . . . . ? . . . . . . . . . . . . . . . . . . 6 6 Exper ime n ta l p l an . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 6 Samp ling r ou tine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 7 Sample p r o c e s sing and ca l cu lat ed va riab l e s . . . . . . . . . . 6 8 S tatistica l me t h ods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 9 5 . 3 5 . 3 . 1 5 . 3 . 2 5 . 4 iv RESULTS AND D I S CUS S I ON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 0 L i vewe i gh t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 0 Woo l g r o wt h . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2 CONCLUS I ON S AND RECOMMENDAT I ONS FOR FURTHER S TUDY . . . 9 1 6 . 6 . 1 6 . 2 A COMPAR I S ON OF I NTAK E AND EFF I C I ENCY ON PAS TURE . . . . . . 9 3 6 . 2 . 1 6 . 2 . 2 6 . 2 . 3 6 . 2 . 4 6 . 2 . 5 6 . 2 . 6 6 . 3 6 . 3 . 1 6 . 3 . 2 6 . 3 . 3 6 . 4 7 . 7 . 1 7 . 1 . 1 7 . 1 . 2 7 . 1 . 3 7 . 1 . 4 7 . 1 . 5 7 . 2 7 . 2 . 1 7 . 2 . 2 7 . 2 . 3 7 . 3 7 . 3 . 1 7 . 3 . 2 7 . 3 . 3 7 . 3 . 4 7 . 3 . 4 7 . 4 7 . 4 . 1 7 . 4 . 2 7 . 4 . 3 7 . 4 . 4 7 . 4 . 5 7 . 5 8 . 8 . 1 8 . 1 . 1 8 . 1 . 2 8 . 1 . 3 I NTRODUCT I ON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 3 MATERI AL S AND METHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 4 Expe r i me nt a l p l an . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 4 Harness a nd bag d e s i gn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 5 C o l l ec t i on r ou t i ne . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 6 Pas ture samp l i ng . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 6 Woo l and body gr owth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 7 S ta t i s t i ca l me t h ods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 7 RESULTS AND D I S CUS S I ON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 8 Measur es o f i nta k e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 8 E f f i c i ency o f l i vewe i gh t ga i n . . . . . . . . . . . . . . . . . . . . . . 1 0 0 E f f i c i e ncy o f woo l gr owth . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0 2 CONCLUS I ONS AND RECOMMENDAT I ONS . . . . . . . . . . . . . . . . . . . . 1 0 7 I NC I DENCE AND DURAT I ON OF HOGGET OESTRUS . . . . . . . . . . . . 1 0 9 I NTRODUCT I ON AND REVI EW OF L I TERATURE . . . . . . . . . . . . . . 1 0 9 The impo r ta nce o f r e pr od uct i ve ra t e t o e f f i c i e n t . . . 1 0 9 Fact o r s a f f e ct i ng t h e o n s e t and durat i on o f oes t r us . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 0 S e l ect i on f or i mpr oved r e p r oduct i ve pe r f o rmance . . . . 1 1 5 Re lat i ons h i ps be twe e n woo l g r owth a nd r e pr od uct i on . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 9 Obj ect i ve s o f t he c ur r e n t r e search . . . . . . . . . . . . . . . . . 1 2 1 MATERI AL S AND METHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2 1 Expe r ime nta l p lan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2 1 R ecord i ng o f r e pr oduct i ve a c t i v i ty and gr owth . . . . . . 1 2 2 S ta t i s t i ca l me t h ods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2 4 RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2 7 L i vewe i ght . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2 7 L i vewe i ght ga i n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2 8 Pube r ty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3 0 R e la t i onsh i p o f h ogget o e s t r us t o woo l gr owth . . . . . . 1 3 1 Re lat i ons h i p o f h ogge t o e s t r us t o two - t o o t h lamb i ng p e f o rmance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3 1 D I S CUS S I ON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4 1 Ewe hogget l i ve we i ght . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4 1 L i vewe i ght ga i n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4 2 Pube rty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4 3 Durat i o n o f t h e b r e ed i ng s eason . . . . . . . . . . . . . . . . . . . . 1 4 5 Re lat i onsh i p t o o t h e r pr oduct i ve charact e r s . . . . . . . . 1 4 5 CONCLUS I ONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4 6 S TAPLE STRENGTH OF FW AND C HOGGET WOOL AND I TS RELAT I ONS H I P TO THE S EASONAL PATTERN OF WOOL GROWTH AND STRENGTH OF ADULT WOOL . . . . . . . . . . . . . . . . . . . . . . . . . . 1 5 0 I NTRODUCT I ON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 5 0 Economi c impo r tance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 5 0 P r ocess i ng S i gn i f i cance . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 5 1 Causes o f p o o r s t r e ng th . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 5 2 8 . 1 . 4 8 . 1 . 5 8 . 1 . 6 8 . 2 8 . 2 . 1 8 . 2 . 2 8 ? 2 ? 3 8 . 2 . 4 8 . 3 8 . 3 . 1 8 . 3 . 2 8 . 3 . 3 8 . 3 . 4 8 . 4 8 . 4 . 1 8 . 4 . 2 8 . 4 ? 3 8 . 4 . 4 8 . 5 V Mea s ur eme nt o f s tap l e s t r e ngth . . . . . . . . . . . . . . . . . . . . . 1 5 3 I mpr oveme nt o f s t ap l e s t r e ngth . . . . . . . . . . . . . . . . . . . . . 1 5 4 Ob j ec tive s o f t h e c u r rent t ria l . . . . . . . . . . . . . . . . . . . . 1 5 7 MATER I AL S AND METHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 5 8 Expe rimenta l p l a n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 5 8 E quipmen t u sed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 5 8 Mea s u reme n t o f s tap le s t r e ngth . . . . . . . . . . . . . . . . . . . . . 1 5 9 S t a tistica l me t hods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 5 9 RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6 4 S o u r c e s o f va ria tion in hand-pu l l grade a nd s t a p l e s t r e ngth o f hogge t samp l e s . . . . . . . . . . . . . . . . . . 1 6 4 Sire and s e l e c tion line e f f e c t s o n s taple s t r e ngth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6 5 The r e l a tion s hip between hand - pu l l grade a nd s t a p l e s t r e ngth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6 8 The r e l a tions hip between ewe h ogget a nd two - t o o t h s ta p l e s t r e ngth . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6 9 D I S CUS S I ON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 8 3 S ou r ces o f va r i a tion in s ta p l e s t r e ngth . . . . . . . . . . . . 1 8 3 S e l e c tion line a nd the s e a s ona l pat t e r n o f woo l gr owt h . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 8 5 The r e l a tions hip be tween hand-pu l l grade a nd s ta p l e s t r engt h . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9 4 Ewe h ogget a nd two - t o o th s t a p l e s t r e ngth . . . . . . . . . . . 1 9 5 S UMMARY AND CONCLUS I ONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9 6 9 . GENERAL D I S CUS S I ON AND CONCLUS I ON S . . . . . . . . . . . . . . . . . . . l 9 8 1 0 . REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 0 3 L i s t o f Tab l e s 4 . 1 Leas t squa r e s means o f p e r f ormance t ra i t s o f FW a nd C rams f e d l u c e r ne d i e t s . a ) P r e l imi nary pe r i od , P 1 ( 1 0 0 0 g/d luce r ne v i presscake ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 9 b ) Chopped l uc e r ne ( 1 4 0 0 g/d ) , P 3 . . . . . . . . . . . . . . . . . . . . . . . . 2 9 c ) P 2 , ? Forma ld ehyde p r o t ec t ed cas e i n . . . . . . . . . . . . . . . . . . 2 9 5 . 1 Leas t squa r e s mea ns ( LS M ) , s tandard e r r o rs , pe r ce ntage advantage ( ( FW-C ) /C ) * 1 0 0 . and s i gn i f i cance o f mon t h ly l i ve we i ght , wea n i ng we i ght (WW) a nd p o s t s hear i ng l i vewe i ght ( PS L W ) by s e l e c t i o n l i ne . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 0 5 . 2 S eas ona l woo l gr owth o f C and FW h ogge ts : l eas t s quar es mea ns ( LS M ) , s tandard e r r o rs , s i gn i f i cance , and pe r c entage advantage ( (FW? C ) /C ) * 1 0 0 . a ) C l ean wo o l g r owt h ( g/day ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 1 b ) Le ngth pe r day ( mm/day ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 1 c ) Ave r age f i b r e d i ame t e r ( Mm ) . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2 5 . 3 Character i s t i cs o f t h e s eas o na l pa t t e r n o f wo o l g r owt h , gr easy f l e e c e we i ght ( GFW ) , c l ean f l e ec e we i ght ( CFW ) , g r easy lamb f l e ece we ight ( LFW ) and average f i b r e d i ame t e r ( FD ) i n C a nd FW she e p . Leas t squar es mea ns , s ta ndard e r r o r s , a nd percentage advan tage ( FW-C ) /C ) * 1 0 0 . . . . . . . . . . . . . . . . . . . 8 9 5 . 4 P o o l ed ( whe r e h omo ge n e o us ) o r wi th i n l i ne ( C/FW ) c o r r e la t i ons b e twe e n measu r e s o f s tap l e s t r e ng th a nd woo l gr owt h characte r i s t i cs ( c o r r e cted f o r DB , BR , DA and S EX ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 0 6 . 1 Measures o f pas t ur e , l i ve we i ght and i n ta k e by s eason and l i n e a ) Past ur e ava i la b i l i ty and d i gestab i l i t y . . . . . . . . . . . . . . 1 0 5 b ) Mo n th ly i n i t i a l l i ve we i gh t . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0 5 c ) DMI and DDMI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0 5 6 . 2 P r od uct i o n and p r oduct i ve e f f i c i e ncy by l i n e a nd s eason a ) ADG and LWGEFF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0 6 b ) CWOOL and CWOOLEFF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0 6 7 . 1 The l i vewe i ght o f e we h ogge ts ( k g ) a ) Year , b i r t h r an k , dam age , s e l ect i on l i ne a nd o e s t r us s tatus l ea s t squa r e s means . . . . . . . . . . . . . . . . . . 1 3 4 b ) Repeated meas ur e s a na lys i s o f l i vewe i ght . . . . . . . . . . . . 1 3 5 7 . 2 L i vewe i gh t ga i n o f e we h ogge ts ( k g ) . a ) Year , b i rth r an k , dam age , s e lect i on l i ne and o e s tr us s tatus l e a s t s quar e s means . . . . . . . . . . . . . . . . . . 1 3 6 b ) Repeated meas u r e s a na lys i s o f seas o na l l i vewe i ght ga i ns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3 7 v. i i c ) Re pe a ted meas ures ana l ys i s o f mon t h ly l i ve we i gh t ga i ns dur i ng the b reed i ng s e a s o n . . . . . . . . . . . . . . . . . . . . 1 3 8 7 . 3a P e r ce n tage o f e we lambs i n o e s t r us by se l ec t i on 1 i n e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3 9 7 . 3 b Ana l ys i s o f dev i a nce f o r ye s / n o d i s play o f o e s t r us a s a hogget . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3 9 7 . 4 C l ea n h o gge t f l eec e we i gh t ( CFW ) a nd winte r wo o l gr owth ( J une g c l e a n wo o l /head/day) i n cyc l i c a nd acyc l i c FW a nd C h o gge ts . . . . . . . . . . . . . . . . . 1 4 0 7 . 5 Two -t o o t h lamb i ng pe r f o r ma nc?o f e we s wh i ch wer e e i t h e r cyc l i c o r acyc l i c a s h o gge t s i n FW and C l i ne s ( n ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4 0 8 . 1 N umbe r o f h ogget s t e s t ed , and two t o o ths r e ? t e s ted f o r s tap l e s t r e ng t h i n t h e f l e ecewe i gh t - s e l ected ( FW ) and Cont r o l ( C ) l i ne s . . . . . . . . . . . . . . . . . 1 7 0 8 . 2 D e scr i pt i on o f hand-pu l l grad e s f or s t a p l e s t r e ngth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7 0 8 . 3 S e l e c t i on l i ne l ea s t squa r e s means , s t andard e r r or s , a nd s i gn i f i cance f o r s ta p l e s t re ngth , hand-pu l l grade a nd wo o l g r owt h characte r i s t i cs . . . . . 1 7 2 8 . 4 P o o l ed ( wh e r e homoge ne ous ) o r w i t h i n line ( C/FW ) c o r r e lat i o n s be twe e n mea s u r e s o f s t ap l e s t r e ng th a nd woo l gr owt h c haracte r i s t i c s ( c o r r ected f o r D B , BR , D A and SEX ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7 6 8 . 5 R eg r e s s i o n c oe f f i c i e nt s , R 2 va l ue s , anc t he s i gn i f i ca nce o f s e l ec t i on l i n e d i f f e r er.ces i n s ta p l e s t r e ngth f o l l ow i ng p read j us tme nt f o r wo o l g r o wt h character i s t i c s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7 7 8 . 6 L eas t s qua r es mea ns f o r s ta p l e s t r e ng th a nd woo l g r owth characte r i s t i cs f o r e a ch hand p?ll grade c lass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . 1 8 2a L i s t o f F i gu r e s 4 . 1 Mea n s h o u l d e r g r ea sy wo o l gr owt h o f f l e e ce we i ght s e l e cted ( FW ) and c o n t r o l ( C ) rams dur i ng un i f o rm f e ed i ng ( 1 kg/d ) i n P 1 , case i n s upp l eme nta t i on i n v i i i P 2 and u n i f o rm f e ed i ng ( 1 . 4 k g/day ) i n P 3 . . . . . . . . . . . . . 3 0 5 . 1 S ea s o na l pa t te r ns o f woo l g r owt h i n FW and C h o gge t s . a ) S e a s o na l va r i at i on i n c l ea n wo o l g r owth ( g/day ) . . . . . . 8 3 b ) S ea s o na l va r i a t i o n i n l e ng t h pe r 2 8 days (mm) . . . . . . . . 8 4 c ) S eas ona l var i at i on i n f i br e d i ame t e r ( Mm ) . . . . . . . . . . . . 8 5 5 . 2 S ea s o na l pa t te r ns o f woo l gr owt h i n FW and c ram a nd e we hogge t s . a ) S ea s ona l var i a t i on i n c l ean woo l g r owth ( g/day ) . . . . . . 8 6 b ) S e a s o na l va r i a t i o n i n l e ngth per 2 8 days (mm) . . . . . . . . 8 7 c ) S ea s ona l var i a t i on i n f i br e d i ame t e r ( Mm ) . . . . . . . . . . . . 8 8 7 . 2 Ca l e ndar o f events f o r e we hogge t s . . . . . . . . . . . . . . . . . . 1 3 3 8 . 1 S chema t i c r e pr e s e nta t i on o f the H ouns f i e ld t e n s ome t e r a nd l oad r e c o rd i ng e q u i pme n t . . . . . . . . . . . . . 1 7 1 8 . 2 P e r ce n tage w i t h i n l i ne d i s t r i but i on s i n FW and C h oggets . a ) Mean s tap l e s t r e ngth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7 3 b ) Hand pu l l grade . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7 4 8 . 3 S u bd i v i s i on o f t h e t ota l sums o f s qua r e s f o r measur es o f s ta p l e s t r e ng th . . . . . . . . . . . . . . . . . . . . . . . . . 1 7 5 8 . 4 D i s t r i but i on o f F W a nd C h ogge ts f or MB , MLFD , MLLPD a nd MLCPD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7 8 8 . 5 Mean s tap l e s t r e ng th a nd t he p r opo r t i on o f f l e e ce we i ght s e l e c t ed ( FW ) a nd c ontr o l ( C ) h ogge ts i n s ta ndard d e v i a t i on ( S D ) c lasses f o r pa i r s o f wo o l gr owt h charact e r i s t i cs a ) FDAMP and MFD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7 9 b ) LLPD and LFD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 8 0 c ) L PDAMP and FDAMP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 8 1 d ) L PDAMP and MFD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 8 2 ix L i s t o f P la t e s 5 . 1 Dye -banded s ta p l e s i n r e l a t i on t o t h e mids ide pa tch . . 7 9 6 . 1 Faeca l c o l l e c t i on bags ( w i t h l i ne r s ) and ha r ne s s e s . . l 0 3 6 . 2 Ha r ne s s ed rams r e t ur ne d t o gra z i ng . . . . . . . . . . . . . . . . . . 1 0 4 1 I NTRODUCT I ON S i ngl e t r a i t f l e e ce we ight s e l e c t i on f l oc k s , s uch as t h e Mas s ey Un i ve r s i ty P T ( P r ogeny T e s t ed ) f l oc k , pr ov i d e e xce l le nt e xpe r i me n t a l mate r i a l f or t h e s t udy o f t h e b i o l og i ca l bas i s f o r ge ne t i c d i f f e r e nc e s i n wo o l prod uc t i on . S im i l a r Aus t r a l i a n Me r i n o f l oc k s have f or me d t h e bas i s f o r s t ud i e s o n s uc h d i ve r s e t r a i ts a s : d ige s t i ve ab i l i ty; i nta ke ; b ody we igh t ga i n; wo o l gr owth e f f i c i e ncy; chem i ca l c ompos i t i on o f woo l; wo o l f o l l i c l e a na t omy; ami n o a c i d me tab o l i sm a nd a range o f o t h e r s ub j ects . Equ i va l en t s t ud i e s have n o t bee n as f u l ly i n i t i a te d i n coa r s e woo l b r e ed s s u c h as t h e N ew Zea l and R omney . Me r i n o s t ud i e s have c o nc l ud e d t ha t d i f f e r e nces i n woo l pr oduct i on , b o th w i t h i n a nd b e twe e n f l oc k s , a r e ma i n l y d u e t o d i f f e re nc e s i n t he e f f i c i e ncy o f c o nve r s i on o f f e ed t o woo l . T h i s t op i c i s o f c on s i d e ra b l e i mpor tance b e cau s e u n l e s s ga i ns i n woo l pr o d uc t i on pe r head a r e due , a t l e a s t i n par t , t o d i f f e r e nc e s i n e f f i c i e ncy t h e n e c onomi c b e n e f i ts f r om f le e ce we ight s e l e c t i o n may be l i m i ted . S he ep wh i ch a r e gene t i ca l ly s upe r i or woo l pr oducer s a r e a l s o s upe r i or i n t h e i r a b i l i ty t o u t i l ize s upplementary ami n o a c i d s f or woo l gr owt h . T h i s i s pa r t i cu l a r l y t r u e f or t h e s u lphur c o n ta i n i ng ami n o a c i d s cys t ( e ) i ne a nd me th i on i ne . L owe r woo l s u lphur c o n t e n t , i n f l eec e we igh t se l e c te d s he ep , i s ma i nta i ne d und e r pe r i ods o f adve rs e nutr i t i on . S e l e c t e d Mer i no s appea r t o have i nc r eased phys i o l og i ca l ve r s a t i l i ty w i t h r e spec t t o woo l gr o wt h . The ab i l i ty t o ut i l i ze n u t r i e nts e f f e ct i ve ly , whe n pr e s e nt , a nd t o susta i n pr od uct i on i n the pre s e nce o f l im i t ed e s s e nt i a l s u bs t ra te s , wou l d appear t o be c l os e t o t h e b i o l og i c a l idea l i n f l e e c e we ight s e l e c t i on pr ogramme s . The e xami na t i on o f b i o l og i ca l d i f f e r ence s , b r ought a b o u t as c o r r e lated r e sponse s , c o u l d a l s o l ead t o the d i sc ove r y o f add i t i ona l tra i ts wh i ch may be i nc o rpora t ed i n t o t h e s e l ect i on c r i te r i a o f pr ime b r ee d i ng s t oc k . Unl i k e t h e Me r i no , t h e New Zea land R omne y i s a h igh l y seas o na l a n i ma l w i t h many aspects o f i ts b i o l ogy be i ng i n f l ue nced by pho t ope r i od . The extent t o wh i ch s e l e c t i on f or f l e e c e we ight has r emoved o r a l te r ed t h i s s eas ona l depende nce i s a n i mp or tant c oncer n f or a n i ma l b r e e de r s . S easona l r e sponse s a r e r e lated t o a n a n imal ' s a b i l i ty t o r eprod uce a s a h ogget , t o l amb a s a n adu l t out o f s eas o n , a nd t o pr oduce wo o l o f r e la t i ve un i f ormi t y thr o ugho u t t he year . S t udyi ng t h e s e pr oduc t i ve d i f f e r ences i n s e l e c t e d l i ne s s h ou ld i nvo l ve i nt e ns i ve i nd o o r t r i a l s i n add i t i on t o f i e ld e va l ua t i ons u nd e r c ond i t i ons wh i c h r e s emb l e t he e nv i r onmen t und e r wh i c h t he s e l i n e s we r e s e l ected . The purpose o f t h i s pr o j ec t was t o e xami n e a var i e ty o f t ra i ts wh i ch a r e c en t r a l t o t h e b i o l og i ca l bas i s o f ge ne t i c d i f f e r ences i n woo l produc t i on o f f l e ec e we ight s e l e ct e d ( FW ) a nd c o n t r o l ( C ) N ew Zea la nd R omne y l i ne s i n t he Mas s e y Un i ve r s i ty PT R omne y f l ock . The pr o j e c t i nvo lved a number o f separat e and c o ncur r e nt t r i a l s d e s igned t o e va l uate s e l ec t i on l i n e d i f f e r e nc e s i n : d iges t i ve a b i l i ty und e r c ontr o l l ed f e ed i ng ; wo o l gr o wt h r e sponse t o s upp le me n ta l d i e tary pr o t e i n; s easona l i ty o f woo l gr owth und e r na t u ra l gra z i ng; body we ight changes f r om wean i ng t o h ogge t s hear i ng; i ntake and e f f i c i e ncy o n pas tur e ; r epr od uc t i ve tra i t s as hogge t s a nd the i r r e l a t i onsh ip t o s u b s e quent lamb i ng per f or mance; and , t h e r e lat i onsh i p be twe e n s eas ona l woo l gr owt h a nd s tapl e s t r e ngth o f h ogget woo l . 2 3 REVI EW OF L I TERATURE The e xaminat i on o f f l oc k s s e l e ct ed f or var i ous meas u r e s o f wo o l pr oduct i on i nc l ud i ng c l e a n f le e c e we ight ( Tu r ne r e t a l . , 1 9 6 8; Dun and Eas t o e , 1 9 7 0; Tur n e r e t a l . , 1 9 7 0; P a t t i e a nd Ba r l ow, 1 9 7 4; McGu i r k a nd At k i ns , 1 9 7 6 ; Heyd e n r yc h e t a l . , 1 9 7 7; Turner a nd Jack s o n , 1 9 7 8 ) , gr easy f l e e ce we i gh t ( B l a i r e t a l . , 1 9 8 5 ) , a nd c r i mp f r equency ( Roba rd s a nd Patt i e , 1 9 6 7 ) have demo ns t ra t ed a var i e ty o f c o r r e l at ed r e s pon s e s t o s e l e ct i on . Exce l l en t r e v i ews o f t h e g e ne t i c a nd phys i o l og i ca l changes i n t h e s e var i ous f l oc k s have bee n pub l i s he d ( Wi l l iams , 1 9 7 6 ; 1 9 7 9 ; 1 9 8 7; McGu i r k , 1 9 7 9; 1 9 8 3; B u t l e r a nd Maxwe l l , 1 9 8 4 ) . 2 . 1 L i ve we ight a nd i nta k e I n t h e abs e nce o f l a rge ( B l a i r e t a l . , 1 9 8 5 ) o r c o ns i s t e n t ( Wi l l i ams , 1 9 7 9 ; 1 9 8 7 ) d i f f e r e nces i n mat ure s ize o f f l e e c e we i gh t s e l ected ( F+ ) s he e p , i t may b e conc luded t ha t f l ee c e we i gh t a nd l i ve we ight we r e r e l a t i ve ly i nd ependent i n mos t s t ud i e s w i t h F + l i ne s . Wh i l e i ncreased l i ve we i gh t c o u ld be a c omponent o f i ncreased f l e ec e we i gh t , d ue to i nc r eas ed s ur face a r ea a nd i nc r eased f e e d capac i ty , i n mos t s t ud i e s the i ncreased i ntake o f l a r g e r s h e ep was on ly i n k e e p i ng w i t h i nc r eased ma i nta i na nc e r e qu i r ements and d i d n o t r e pr e s e nt a large p roduc t i ve advantage ( W i l l i ams , 1 9 7 9 ) . D i r e c t c ompar i s o ns o f v o l untary f eed i ntake o f F + ve r sus C l i n es have be en conducted b o t h i n and out o f d o o r s . The c o nc l us i on has genera l ly b e e n t ha t d i f f e re nces i n i nta k e ( wh e n ad j us ted f o r l i ve we i gh t ) d o n ot r epresent s i gn i f i ca n t c o n t r i bu t i ons t o d i f f e r e nc e s i n woo l pr oduct i on ( Ahme d e t a l . , 1 9 6 3; Wi l l iams a nd M i l l e r , 1 9 6 5 ; D o l l i ng a nd P i pe r , 1 9 6 8; Hami l t on and Lang land s , 1 9 6 9 ; R obards et a l . , 1 9 7 4 ) . S i mi l a r wor k compa r i ng b r e e d s a nd s tra i ns ( Da ly a nd Car t e r , 1 9 5 5; We s t o n , 1 9 5 9 ) a l s o c o nc l uded that v o l unta ry i nt a k e was n o t a r e l iab l e pred i ct o r o f wo o l pr oduct i on i n t h e p r e s e nce 4 o f s ubstant ia l ly l a rge r va r i a t i on i n wo o l gr owth e f f i c i e ncy . Al t h o ugh S c h i nk e l ( 1 9 6 0 ) s howed s ign i f i ca n t contr i but i ons o f vo l unta ry i nta k e t o be twe e n s he e p d i f f e r e nces i n woo l p r oduct i on , s ubsequent s t ud i e s ( Hu tch i ns o n , 1 9 6 1 ; Wi l l i ams , 1 9 6 6 ; Wodz ic k a -Toma szews ka , 1 9 6 6 ; a nd 1 9 68 ; ) Savi l l e a nd R obard s , 1 9 7 2 ) have c o n t e st ed t he s t r e ngth o f t h i s r e la t i ons h i p . 2 . 2 Wo o l gr owth e f f i c i e ncy S e l e c t i on f o r f l e e c e we ight appear s to have r e s u l te d i n i mpr oved f l ee ce we ight a nd a c o r r e l a t e d r e spome i n e f f i c i e ncy . R e l a t i ve l eve l s o f woo l p r od uc t i o n pe r un i t o f f e e d i ntak e have be e n summa r ized by But l e r and Maxwe l l ( 1 984 ) a nd range f r om a 9 % advantage ( Ahme d e t a l . , 1 9 6 3 ) , t o a 7 1% adva ntage ( Hami l t o n a nd Langland s , 1 9 6 9 ) ove r a r ange o f f e e d i ng l e ve ls . M ost e s t i mate s a r e betwe e n 9 % a nd 38% ( Do l l i ng a nd M o or e , 1 9 6 0 ; W i l l i ams a nd Wi nsto n , 1 9 6 5 ; Wi l l i ams , 1 9 6 6 ; Langland s , 1 9 6 9 ) . and , 1 9 68 ; Hami l t on a nd S t ud i e s c ompa r i ng betwe e n b r e ed o r b e twe e n stra i n d i f f e r e nc e s i n woo l gr owth e f f i c i e ncy have r epo rte d s imi lar var i a t i on w i t h va l ue s rangi ng be twe e n 0 % a nd 5 4 % r e l at ive advantage o f o ne b r e ed/s tra i n ove r a n o t h e r ( Da ly a nd Car t e r , 1 9 5 5 ; We s t on , 1 9 5 9 ; Dun l op e t a l . , 1 9 6 0 ; Dun l op e t a l . , 1 9 6 6 ; Langlands a nd Hami l t o n , 1 9 6 9 ; Sav i l l e and R obards , 1 9 7 2 ; S umne r , 1 9 7 9 ) . Cor r e l at ed r e s p o ns e s i n woo l gr o wt h e f f i c i e ncy have n o t b e e n f o und i n Cr i mps m i nus s e lect i on f l oc k s ( Ro bards e t a l . , 1 9 7 4 ) , i n s k i n f o l d p l u s f l oc k s ( Robards e t a l . , 1 9 7 6 ) o r i n f e r t i l i ty p l us o r body we ight p l us f l oc k s ( Patt i e a nd W i l l i ams , 1 9 6 7 ; Atk i ns a nd R obards , 1 9 7 6 ) . H igh body we ight s e l e c t i o n f l o c k s d id pr oduce mo r e wo o l , but wi thout accompany i ng changes in e f f i c i e ncy . 5 Many o f the r e p o r t e d s t ud i e s have f ound t ha t t he r e l a t i ve advantage o f va r i ous gr o ups i s d e pendent o n t h e l eve l o f n u t r i e nt i ntak e . T h e mos t d rama t i c e xamp l e i s t hat o f Hami l t o n and Lang lands ( 1 9 6 9 ) i n wh i c h F + and F - rams gra z ed t h r e e past ur e s d i f f e r i ng i n h e r bage ava i la b i l i t y . T h e r e la t i ve advan tage o f F + ove r F - rams i nc r ea s ed f r om 1 3 8 % t o 2 4 2 % a s he r bage qua l i ty and a va i lab i l i ty i ncreased . S imi l a r r e s u l ts have bee n r ep o r t ed i n o t h e r s e l ec t i on l i n e a nd b r e ed/stra i n c ompa r i s ons ( We s t o n , 1 9 59; S c h i nc k e l , 1 9 60; W i l l i ams a nd W i ns t o n , 1 9 6 5; W i l l iams , 1 9 6 6 ; McManus e t a l . , 1 9 6 6; P i per a nd Do l l i ng , 1 9 6 9; Sav i l le a nd Robards , 1 9 7 2 ) . The e f f i c i e ncy o f c o nve r s i on o f f e ed i nt o wo o l appears t o be a ma j o r fact o r c o nt r i but i ng t o va r ia t i o n i n woo l p r oduct i on when c ompa r i s ons a r e mad e be t we e n gen otype s . Much o f t h e w i t h i n f l ock va r ia t i on appe a r s t o b e und e r s imi lar c o n tr o l . What r ema i ns t o b e d e t e rm in ed i s t h e phys i o l og i ca l r ou t e s t h r o ugh wh i ch e f f i c i e ncy h a s be e n i ncreased . Thes e pat hs may i nvo l ve t h e qua l i ty o f f or age consumed und e r f r e e cho i c e gra z i ng; the ab i l i ty o f t h e d i g est i ve t ract t o abs o r b a l a r g e r quant i ty o f n u tr i e n t s f r om i ngested f orage; o r d i f f e r e nces may b e d u e , pr i ma r i ly , t o c hanges i n t h e pos t? abs o r pt i ve ut i l i za t i on o f n ut r i e nt s . 2 . 2 . 1 D i e t s e l e c t i o n Ev i d ence o n t he s e l e c t i v i ty o f i nta k e by l i nes , b r e eds o r s t ra i ns appears t o b e amb i gu o us . Us i ng t h e n i t r ogen a nd c rude-f i b r e c o n t en t o f f a e c e s as a g u ide , Wes t o n ( 1 9 59 ) c o nc l uded tha t s t r o ng -wo o l Me r i nos s e l ect ed f e e d o f s l i gh t ly h i gh e r qua l i ty than f i ne -woo l Mer i nos . M o o r e a nd D o l l i ng ( 1 9 6 1 ) f o und a 1 0 % c o e f f i c i e n t o f va r ia t i on , i n nutr i t i ve va l ue o f f e ed c o ns umed , t ha t was r e lated t o f e e d s e l ec t i on by t h e s he e p . Ahmed e t a l . ( 1 9 6 3 ) we re unable t o d emons t rate , i n a p e n f ee d i ng t r i a l , any pr e f e r e nc e o f F + f o r d i e ts wi th h i gh e r p r o t e i n c ontent . Var i ab i l i ty i n d i e t s e l e c t i on d o e s n o t a ppear t o be a ma j or f actor i n f l ue nc i ng the variation in efficiency of wool production between genotypes. 2.2.2 Digestive ability 6 The increased efficiency of feed conversion in F+ animals may also be related to differences in the ability to digest or absorb dietary nutrients. Hutchinson (1961) found considerable individual differences in apparent digestive ability but was unable to significantly relate these to measures of efficiency. Weston (1959) found small but significant increases in the ability to digest nitrogen in strong wool Merinos (2%). In a study by Brookes (1983,unpublished), subsequently reported by McClelland et al., (1986), c rams had higher apparent abilities to digest dry matter (62.9?.6% vs. 60.1?.9%) than FW rams. Other reports have demonstrated inconsistent small and non? significant differences between lines and strains (Dunlop et al., 1966; Piper and Dolling, 1969; Robards and Atkins, 1976). Williams (1979) quoted that the concentrations of ammonia in the rumen fluid were similar for F+ and F- sheep. Given relatively large strain differences in efficiency and small and inconsistent differences in apparent digestive ability, it is unlikely that digestive ability or the total quantities of nutrients available to the sheep has been altered by selection for fleece weight? The possibility of differences in apparent digestive ability must be completely ruled out, however, before comparisons of dietary intake (based on faecal output) are used to compare selection lines. Metabolic rate has not been shown to differ between F+ and c or F- flocks (Williams and Miller, 1965; Williams and Winston, 1965) although Graham (1968) showed some evidence of higher fasting heat production in F+ compared to F- rams. 7 2.3 Utilisation of amino acids for wool growth 2.3.1. Sulphur content of wool Many of the ongoing studies into differences in wool growth efficiency are centered on the availability and utilisation of amino acids. These investigations have focused on the sulphur-containing amino acids (S-amino acids) cyst (e)ine and methionine and their relationship to the sulphur content (S-content) of wool. Most of the sulphur in wool is present as cystine with smaller amounts of cysteine and methionine. These S-amino acids are not spread homogeneously throughout the wool fibre, rather, separate sub-fractions of the soluble proteins extracted from wool contain differing amino acid balances (Bradbury, 1973). Low sulphur proteins, concentrated mainly in the microfibrils of the cortical cells, account for over 60% of wool proteins and contain all of the methionine and most of the lysine found in wool. High sulphur proteins, concentrated primarily in the matrix proteins surrounding the microfibrils, contain large amounts of cystine, proline and serine. High tyrosine proteins, also in the cellular matrix, are rich in tyrosine and glycine but do not contain many other amino acids. The balance of cortical cell types within a fibre is also related to the s-content of wool. The s-content of fibre cell types varies considerably, decreasing in order from para-, meso-, ortho-, and meta-cortex to medulla (Black, 1987). Fine fibres, with higher crimp frequency and high paracortex content, will have higher s-content than coarse fibres containing more orthocortex and (perhaps) medulla. Although the commitment of fibre cells to specific cortical types remains reasonably constant over a wide range of wool growth rates, it can be affected by both plane of nutrition and photoperiod (Orwin et al. 1984). In a similar but qualitative study, Woods and Orwin (1987) showed that the 8 wool proteins of individual sheep remained constant and characteristic despite changes in season, age or nutritional status and did not vary between different body positions. Between-sheep differences in protein pattern were displayed most markedly in the high-sulphur group. Differences in protein pattern were presumed to reflect genetic differences between sheep (Woods and Orwin, 1987). The relationship between S-content, protein profiles, and the balance of cortical cell types has not been fully explored in Romney fleeceweight selection lines. Phenotypic associations between the S-content of wool and wool growth have clearly been demonstrated (Reis, 1965; Reis and Williams, 1965, Reis and Tunks, 1968; Reis, 1979). In all cases, high wool production was associated with lower s? content of the wool. Differences in the S-content of wool in selected Merino sheep have also been demonstrated and result from F- or C sheep having a greater proportion of the high sulphur proteins than F+ sheep. Within this group of proteins, there is also a change in the balance of high cystine proteins (Williams, 1987). These compositional changes related primarily to resistance to compression and super? contraction properties. These were higher, and lower, in high s-containing wools, respectively. No differences were found on stressjstrain properties at 30% fibre extension. The lower concentration of S-amino acids in the wool of F+ sheep is not merely a consequence of dilution. F+ sheep have higher daily sulphur outputs than C or F- sheep (Williams, 1979; 1987). F+ sheep are capable of increasing the s-content of wool when supplementary s-amino acids are supplied. To date, no differences in the S-content of the Massey University FW and C lines have been published, but investigations are underway. 9 2.3.2 Metabolism of sulphur-containing amino acids Many studies have documented the response in wool growth to supplementary supplies of S-amino acids (Reis, 1979). Supplementation of S-amino acids increases wool growth rate, and the S-content of wool. This relationship is more pronounced in F+ than F- or c sheep (Williams et al. , 1972; Williams, 1973;1976). S-amino acids in the form of L-cysteine, L-methionine or DL? methionine produced similar results whether given as abomasal supplements ( Reis, 1967; Williams et al. , 1972; Reis et al., 1973), intravenous infusion (Downes et al. , 1970; Reis et al.,1973), or intraperitoneal or subcutaneous injection at one or two day intervals ( Wickham, 1970; Barry et al., 1973). Supplementary S-amino acids can also be supplied via abomasal supplies of casein. Reis (1979) summarized a number of studies with protein supplementation and concluded that amino acid imbalance in the supplement may yield poor wool growth response. This was true for gelatin and zein, while casein was fairly successful in stimulating wool growth. When a mixture of amino acids, including 10 essential amino acids, was infused into the abomasum, it stimulated wool growth to a similar extent as that of an equivalent amount of casein (Reis and Tunks, 1978). The concentration of free cystine in the plasma has been found to be lower in F+ Merino lines (Williams et al., 1972; Williams, 1976). Although this difference is observable at very young ages (Williams, 1984) the mechanisms controlling this concentration difference have proved to be elusive. Studies using radioactive cystine, have shown no differences in the entry rate of cystine into the plasma (Williams et al., 1972; Williams, 1976). Differences in plasma cystine 10 concentration in these flocks were also independent of the level of wool growth. All results have demonstrated that superior wool growth is not due to higher availability of cystine in F+ sheep, or to the proportion of cardiac output supplying the skin (Williams, 1987). Ultimately, the causejeffect relationships need to be more clearly defined, and further understanding of the genes controlling wool protein synthesis is needed. The importance of S-amino acid metabolism in the Massey FW and C lines is the subject of considerable recent study. Consistently lower blood urea concentration in FW rams has been related to lower rates of urea excretion (McCutcheon et al., 1987). Clark (1987) also reported that intravenous infusion of methionine reduced plasma urea concentration in C rams to a greater extent than that of FW rams. If, as in Merino lines, the wool of FW sheep has a lower s-content than that of C lines, this may indicate that high plasma urea concentrations of c rams reflect greater deamination of non-S-amino acids. The metabolism of S-amino acids appears to be related to plasma concentrations of urea. McCutcheon et al.,(1987) found a high (r=-0.85) correlation between corrected plasma urea concentration and nitrogen retention. The high blood urea concentration of some rams appears to reflect greater amino acid deamination consequent upon their inability to retain a high proportion of dietary nitrogen in wooljbody tissues. MATER I AL S AND METHODS 3 . 1 D escr i pt i on o f t he e xpe r i me n ta l f l o c k s and t he i r manageme n t 1 1 The s he e p u s ed i n t h e s e s t ud i e s we r e f r om t he f l e e ce we ight s e l e c te d ( FW ) a nd c o n t r o l ( C ) s ub f l oc k s o f the Mas s ey Un i ve r s i ty P T ( pr ogeny t e s t ed ) R omne y f l oc k . B o t h l i n e s we r e e s tab l i s he d f r om t h e same bas e R omne y f l ock , d e s c r i be d b y Rae ( 1 9 58 ) , i n 1 9 5 6 a nd have b e e n c l os e d s i nc e 1 9 58 . T h e manageme nt a nd s e l e c t i on me thods u sed s i nce tha t t ime have b e e n d e sc r i be d i n d e ta i l by B la i r e t a l . ( 1 984 ) but a r e s umma r ized h e r e . Each l i n e has be e n ma i nta i ned a t 70-80 e we s and b o t h l i n e s a r e grazed t oge t h e r . Ewe s wer e c u l l e d f o r age a ft e r the i r f our t h lamb i ng . F o u r 1 . 5 year o l d r ams we r e r e p l aced e ach yea r . Re p laceme nt 1 . 5 yea r o l d e we s a nd rams we r e s e l ec t e d a t r andom i n t h e C l i n e wh i le F W r e p laceme nts wer e t h o s e w i t h the h e av i e s t greasy f le e c e we igh t s as h ogget s . Oes t r us e we s f r om b o t h l i n e s wer e p e n mat ed t o i nd i v i d ua l rams be twe e n Ma r c h a nd Apr i l . Lamb i ng occure d be t we e n Augus t a nd S e pt embe r . S ho r t ly a f t e r b i r t h each lamb was t agged t hen b i r t h d a t e , s e x , b i r t h r a n k a nd dam i d e n t i f i ca t i on we r e r e c o r d ed . Lambs wer e weaned a nd we ighed i n l a t e November a nd s h o r n i n m i d Decembe r . F r om lamb s hea r i ng u nt i l h ogget s hear i ng i n e a r ly Oct o be r , r am a nd e we h ogge ts we r e grazed s e pa rate ly . Wi t h i n s e x , h ogget s f r om b o t h l i n es wer e grazed t oget h e r o n r ye gras s? wh i te c l ove r pas ture s . H ogget f l e e ce s , i nc l ud i ng be l l i e s and p i e ce s , wer e i nd iv i d ua l ly we ighed a nd r ecorde d . L i v e we ights we r e ta k e n d i r e c t l y o f f s he a r s . A sample o f wo o l f r om the r ight mi ds i d e o f each f l e e c e was c o l l e ct ed and labe l l ed f o r la t e r d e te rmi na t i on o f d e s c r i pt ive t ra i ts , c l ean y i e ld a nd f i b r e d iamet e r . 1 2 S e l e c t i o n o f FW a nd C a n i ma l s t o e n ter e xper ime nt s was p ure ly o n a random bas i s . Whe never p oss i b l e , a l l ava i la b l e a n ima l s were measured . Measurements o f s easona l woo l growth a nd s easona l reprod uc t i on were c onducted under t h e s tandard manageme nt prac t i c e s o f t he f l ock. No e f f ort was mad e t o a l t er t he n u tr i t i on or growt h rat e s o f l ambs o n past ure. 3 . 2 Ana lyt i ca l t echn iqu e s e mgloyed 3 . 2 . 1 Data c o l l e c t i on and c orrect i on Al l data were ed i ted pr i or t o ana lys i s t o remove records wh i c h d i d n o t phys i ca l ly c o n f orm t o t h e requ ireme n t s. Th i s i nc l uded remov i ng a l l h o gge t s wi t h i nc omp l e t e s ea s o na l data (Chapter 5 ) , remov i ng a n i ma l s wi t h unkn own va l ue s f or s ire , b irth date , dam, b irth rank a nd wea n i ng we ight . Ewes wh i c h were i n j ured o r d i ed d ur i ng t he breed i ng s ea s o n were n o t c o ns idered i n t he c ompar i s o n o f i nc i d enc e o f o e s trus (Chapter 7 ) . I n prac t i s e , very f ew records were omi t t ed , e s pe c ia l ly i n i nd o or tr i a ls . A ft er pre l imi nary s cre e n i ng o f rec ords , a l l data were p l o t ted aga i ns t s he e p number (unre lated variab l e ) f or t he i de n t i f i ca t i on o f o u t l y i n g va l ue s due t o mi sc od i ng. Var iables requ ir i ng e x tra c omputa t i on were ca l c u la t e d us i ng F ortran programs t o m i n imi z e errors. S t a t i s t i ca l a na l ys e s were performed us i ng b o t h S AS (S tat i s t i ca l Ana l ys i s S ys te m, S AS I ns t i t ut e , Cary, NC , USA ) and REG (Genera l i ze d Regres s i o n Package , A . G i lmour , N. S . W . De pt o f Agr i c u l ture , ) . 3 . 2 . 2 Un ivar ia t e a nd Mul t ivariate ana l ys i s o f var i a nce Much o f the data a na l ys e d i n these e xperi ments re presents repeated observa t i ons o n t h e same a n ima ls. Al t h ough t h i s t ype o f data c o u ld b e a na l ys e d us i ng u n i varia t e a na l ys i s o f 1 3 var i a nce ( ANOVA ) a t each d i s c r e t e samp l i ng , o r us i ng u n i va r i a t e ( typ i ca l ly s p l i t -p l o t ) ANOVA cons ide r i ng t ime a s a d e s i gn fac t o r , these app r oach e s d o n o t ava i l thems e l ve s o f a l l t h e i n f orma t i on wh i ch i s ava i l a b l e . Us i ng t h e s e a pproaches may l ead t o e r r one o us e r r o r t e rms ( sp l i t - p l o t ) o r l e s s p owe r f u l t e s t s o f ma i n e f f e c t s ( s e parate ANOVA ) ( Bo x , 1 9 5 0 ; Dan f ord e t a l . , 1 9 6 0 ; C o l e a nd G r izzle , 1 9 6 6; G i l l a nd Ha f s , 1 971; Bryant a nd G i l l i ngs , 1 985 ) . The pr e fe r r ed me t h od o f a na lys i ng the s e dat a i s t o a pp ly mu l t i va r ia t e a na l ys i s o f var i ance ( MANOVA ) . O n e t ype o f MANOVA wh i ch i s pa r t i cu lar l y s u i te d t o g r owt h d a ta i s r e fe r red t o as Repeated Measu r e s Ana lys i s ( RMA} . Whe n s ome yi e ld va r iab l e y i s meas u r ed over p pe r i ods , o n t h e same a n i ma l , t he n t o d o s e pa r a t e ANOVAs wou l d b e t o d i s r egard t he c or r e la t i ons wh i c h e x i s t acr oss the p ? d imen s i oned vec t o r s o f y . Thus , e ach a n i ma l i s r e p r e s e n t e d by a vec to r r a the r t han a s i ng l e o bs e r va t i on . S ums o f squa r e s a nd c r o s spr oducts , i n ANOVA , a r e r eplaced by a mat r i x c ons i s t i ng o f s ums o f squar e s f or each y ( on t h e d ia g o na l ) a n d s ums o f c r o s sproducts b etwe e n a l l y ' s o n t h e o f f -d iagona ls . The advantage o f t h i s t echn ique i s that d i r e c t c ompar i s ons o f t ime e f f e ct s , a nd mor e powe r f u l t e s t s o f ma i n e f f ects a r e made beca u s e a l l ma i n e f f e c t ( re pe a t e d} data i s i nc l uded . The i nt e r ac t i on o f ma i n e f f e c ts w i t h t ime can a l s o be a s s essed . I n t h e u n i va r i a t e ANOVA, hyp o t h e s e s a b out main e f f e c t s we r e mad e v i a a n F -tes t , f ormed by a r a t i o o f mean squa r e s . I n t h e mu l t i va r ia t e cas e , t e s ts o f hyp o t he s i s are mad e o n H ( hypo t he s i s ) a nd E ( e r r or} mat r i ce s . These mat r i c e s a r e d imens i oned pxp . H a nd E mat r i ce s a r e f ormed by t h e appr o pr ia t e mu l t i p l icat i o n o f i d e n t i ty a nd contras t ma tr i ce s t o a cc ount f or n a n ima l s a nd k c oe f f i c i e nts . A number o f d i f f e r e nt c ontras t matr i ce s can b e u s ed t o gene rate hypot h e s e s about ma i n e f f e c ts a nd i nt e ract i ons . 1 4 Once H a nd E a r e f orme d , t he g ene r a l t e s t o f ma i n e f f ects can be d on e by a var i e ty o f me t hods ( Mo r r i s on , 1 9 7 6 ; Cha t f i e ld a nd Co l l i ns , 1 980 ) . A lthough n o one o f t h e s e me thods has won un i ve r s a l acceptance , t h e me t h od o f W i l k s ( 1 9 4 6 ) us i ng t he l i k e l i ho od appr oach o f Ne yman a nd P ea rs on ( 1 928 ) i s s tr a i gh t f o r ward a nd fa i r ly r ob u st ( Bo x , 1 9 50; Dan f o rd e t a l . , 1 9 60 ) . Whe r e s imp l e r a t i os o f mea n squa r e s ( S SQ/d f ) f or m hypo t h e s i s t e s ts i n ANOVA, t h e d e t e rm inants o f t h e H a nd E ma t r i ce s f orm a t e s t rat i o i n MANOVA whe r e , r = E H + E a nd M = n l n ( 1/r ) A1= ( p + ( k + 1 ) + 1 ) I 2 n t o f or m t h e t e s t s t a t i s t i c ( 1 -A1 ) M wh i c h i s d i s t r i bu t e d a s Ch i -squar e w i t h p ( k - 1 ) d e g r ees o f f r e e d om . 3 . 2 . 3 Tes t s o f Ass umpt i ons i n MANOVA The o n ly a s sumpt i on c r uc i a l t o MANOVA i s h omoge ne i ty o f the var iance - cova r i ance ( VCV ) mat r i ce s - s im i l a r t o a mat r i x e xt e ns i on o f Bar l e tt ' s te s t . As th i s s t a t i s t i c was n o t ava i l a b l e t h r ough R EG o r S AS , i t was ca l c u l a t e d f r om t h e matr ice s o f s ums o f squares a nd c r os sproducts ( S SQCP ) , wh i ch can be o u tput f r om t h e REG o r SAS pr ograms accord i ng t o t h e me thod o f B o x ( 1 9 50 ) . I n n o case was t he r e s i g n i f i cant d ev i a t i on f r om h omogene i t y . Th i s s tat i s t i c i s ca l c u l a t ed as be l ow : L e t nt = numb e r o f a n i ma l s per t reatmen t p = numb e r o f pe r i ods k = number o f t r eatments N = t ota l numbe r o f a n i ma l s lEt I = t h e d e te rm i nant o f t he w i t h i n t r e atme nt gr o up e r r o r VCV ma t r i x lE I = t h e d e t e r m i nant o f the e r r or VCV mat r i x 1 5 The d e t e rmi nants o f a VCV ma t r i x can be found d i r e c t l y fr om t h e d e t e rminants of t h e SSQCP mat r i x I VCV I = I SSQCP I I ( df ) P a nd 2p2 + 3 p - 1 [ A1 = - - - - - - - - - - - -6(p+1 ) ( k- 1 ) a nd note : df ( E ) =N-k , df ( E t ) = nt- 1 k 1 1 ] r: - - - - -t = 1 nt-1 N-k M = ( N-k ) l n I E I - r: [ ( nt-1 ) l n I Etl J The t e s t c r i te r i a ( 1 -A1 ) M i s d i s t r i buted a s Ch i -squa r ed w i th f? df whe r e f? = ( 1/ 2 ) ( k- 1 ) (p ) (p + 1 ) . D i s cuss i ons of the i n t e rac t i on be twee n t ime a nd ma i n effec t s r efer t o t h e d epa rtu r e fr om para l l e l i s m of t r eatme n t effe cts . Th i s pa ra l le l i s m d o e s n o t mean l i near i ty a c r os s t ime . I t r efer s t o t h e p r e se nc e o r absence of c onstant d iffe r ences be twe e n t r ea tmen t s a c r o s s t ime pe r i od s . MANOVA i s c apa b l e of maki ng t h e s e c ompa r i s ons , wh i l e t hey a r e d iff i c u l t t o quant ify o t h e rw i s e . In add i t i on t o MANOVA , un i va r i at e a na l ys e s wer e c onducted , a s par t of RMA, a t e a c h t i me i nt e rva l i n order t o d e t e rmi ne when , i n the pr oduc t i on cyc l e , s i gn if i cant s e l ec t i on l i n e d iffe rences we r e occur i ng . THE PERFORMANCE OF FW AND C HOGGETS FED LUCERNE D I ETS WI TH AND WI THOUT FORMALDEHYDE-PROTECTED CASEI N 4 . 1 I n troduc t i on 1 6 The i nh e r e n t d iff i c u l t y i n o bta i n i ng f i e l d measureme nts o n pr oduct ive chara c t e r s s uch a s fe ed i n take , me tabo l i c o r d i ge s t ive a b i l i ty , a nd eff i c i e ncy l e nd s ome appe a l t o p en? feed i ng e xpe r i me nt s a nd the i r use as pre l im inary gu id e s t o mor e e xhaus t ive f i e l d r e s earch . Know l edge of these c haract e r s i s e s s e nt i a l t o p rov ide a bas i s for l ater f i e l d c ompa r i s ons wher e e s t i mat e s of i n take may b e based e nt i r e l y o n fae ca l o u tput , a nd the und e r l y i ng a s sumpt i on of n o s i gn i f i cant d iffer e nc e s i n d ry mat t e r o r n i t r ogen d i ge s t i ve a b i l i ty. Se l e c t i on for f l e e c e we i ght i n Mer i nos has brought about a c o r r e lated i nc r e a s e i n the eff i c i e ncy of c o nve r s i on of fo od t o wo o l . The c o r r e l at ed r e s ponse s i n i ntake a nd body s ize have be e n var i a b l e ( Bu t l e r a nd Maxwe l l , 1 9 8 4 ) . S im i lar s t ud i e s us i ng R omne y s h e e p ( Clark et a l . , l 9 6 5 ; Wodzi cka? Tomasewska , 1 9 6 6 ) have repor ted that w i th i n fl ock d iffe r e nc e s be twee n s h e e p w i t h h i gh o r l ow f l eece we i ght we re d ue t o d iffer e nc e s i n t h e eff i c i e ncy of c onve r s i on of food t o woo l . Woo l a nd body gr owt h have be e n s h own t o r espond pos i t i ve l y t o abomasa l s upp l e me n tat i on w i th cas e i n o r S-ami no a c ids ( Re i s , 1 9 7 9 ) . F le e c e we i gh t s e l e c t ed Me r i nos a re mor e eff i c i e n t a t d i r e c t i ng these supp lemen t s t owards woo l growth ( Wi l l i ams et a l . , l9 7 2 ) . Equ iva l ent s t ud i e s w ith s e l e c t i on l i ne s i n R omneys have o n ly r e cent ly be e n r epor ted ( McCl e l land et a l . , 1 9 8 6 ; Clark, 1 9 8 7 ; McCutche on et a l . , 1 9 8 7 ) . P r i or t o t h i s t r i a l , FW and C s h e ep had o n ly b een s t ud i ed i n 1 7 o ne i ndoo r e xpe r i me n t . Us i ng data from a n e xpe r i me n t o n 1 2 FW a nd 1 2 C rams fed c u t pas tur e a d l i b i t um, McC l e l l and e t a l . , ( 1 9 8 6 ) found FW s he e p t o b e i nfe r i or t o C s h e e p i n t h e appar ent a b i l i ty t o d i ge s t d ry mat t e r ( 6 0 . 1 ? 0 . 9% vs. 6 2 . 8 ? 0 . 6% . ) . Da ta on wo o l a nd body gr owth in t h e s e same rams y i e lded a s i gn i f i cant p o s i t i ve r e l a t i onsh i p b etwee n i ntake a nd woo l g r owth i n FW rams and a s i g n if i can t n ega t i ve r e l a t i onsh i p among C r ams. C rams a l s o ma i nta i ned s i gn i f i cant ly h i gh e r g r owth r a t e s d ur i ng the t r i a l . The s e a nd o ther r e s u l t s i nd i ca t ed t ha t t h e adva ntage of FW r ams was d ue , a t l e ast i n par t , t o d iffe r enc e s i n the a b i l i ty t o d i r e c t absorbed n u t r i e nt s t oward woo l gr owth. L i n e d iffe renc e s i n wo o l g r owth we r e mor e pronounced among s h e e p w i t h h i gh e r i ntakes. The purpose of t h i s s t udy was to e xamine t he r e l a t ive woo l g r owt h , l ivewe i ght ga i n , appa re n t d i ge s t ive a b i l i ty, a nd u t i l i sat i on of d i e ta ry p r ot e i n by FW and C Romney rams. 4 . 2 Mate r ia l s and Me t h ods 4 . 2 . 1 Expe r i menta l p la n N i ne FW and n i ne C r am hogge t s , b o rn 1 9 8 3 , wer e c h o s e n a t random off pas ture a nd b r o ught i nd o o r s . Rams we r e h o u s ed a nd f ed i n i nd iv i dua l d i g e s t ab i l i ty crates f o r t h e d ura t i on of t he expe r iment . The e xper i me n t , a t ota l of 1 8 we eks beg i n n i ng May 0 1/ 1 9 8 4 , was d iv ided i nt o 3 s ubpe r i od s ( P l , P 2 , P 3 ) e ach of 6 weeks . The f i r s t two we eks of each p e r i od wer e used t o ad j us t r ams t o t he e xpe r i me nta l d i e ts a nd t o s tab i l i z e i ntake s . Woo l g r owt h , l ivewe i ght ga i n a nd d i ge s t ive ab i l i ty we r e mea s u r ed i n the last 4 , 4 a nd 2 we e k s of each 6 week pe r i od , r espe ct ive ly. P 1 was a un iformi ty , o r c ova r i ance pe r i od , dur i ng wh i ch a l l s h e ep r e ceived an equa l we i ght of fe e d , ca lcu lated t o be above mai nta i nance . Woo l gr owth i n P l was used as a c ova r i a t e i n the a na l ys i s of P 2 a nd P 3 data . 1 8 Dur i ng P 2 , t h r e e s h e ep from each l i ne we r e ass i gned a t random t o r e ceive e i ther 0 , 3 0 o r 6 0 g pe r day of forma l d ehyd e pr o t ected cas e i n i n t h e fe e d i n add i t i on to t he basa l d i e t fed i n P l . An add i t i ona l 2-week ad j ustmen t p er i od ( no t i nc l uded i n t he s e ana l ys e s ) was p laced be twe e n P 2 a nd P3 t o a l l ow for t h e gradua l t rans i t i on from f i ne t o l ong cut l ucerne d i e ts . In e ach of four 3-day s tage s , the propor t i on of new fe ed was i nc r ea s ed by 2 5% and t he l eve l of fee d i ng was ra i s ed by l O O gms . Dur i ng P 3 , a l l s h e ep cont i nued t o be fed a s imi l a r amount of h i gh e r q ua l i ty d i e t . 4 . 2 . 2 . F eed i ng In pe r i o dsPl a nd P2 each s he e p r eceived l O O Og per day ( a i r dry bas i s ) of prote i n e xtracted l u c e rne mea l obta i ne d from Z anpro Lucerne ( NZ ) Ltd . The d i e t was f i ne l y gr ound a nd unpe l l e te d . Dur i ng pe r i od P3 each s h e e p was fed 1 4 0 0 gms per day ( a i r dry bas i s ) of c haffed l ucerne . P ure cas e i n , o bta i ned from the Da i ry Research Ins t i tute , Pa l me r s o n Nor t h , was treated by s oak i ng 2 0 0kg of cas e i n i n 1 0 0 01 of c o l d wate r t o wh ich 51 of 4 0% forma ldehyde had b e e n added . Afte r 6 0 mi nutes a g i tat i on , t h e ca se i n was d r i ed t o 1 0% mo i s t ur e . The forma ldehyd e cas e i n , thus obta i ned , was s t or e d unde r r efr i ge rat i on a nd m ixed t h o r ough ly w i th i nd iv idua l da i ly presscake rat i ons ( P 2 ) b efore feed i ng . She e p we r e fed once da i ly a t 0 8: 3 0 h o u r s after r emova l of r efused feed from t he prev i o us day . Dur i ng pe r i odsP1 a nd P.l., da i l y r efusa l s wer e dr i ed a t 1 2 0 ? F for 2 4 hours and 1 9 then we i ghed . Dur i ng pe r i od s ome s h e e p r efus e d a g r eater p r opor t i on o f s ta lk than l eaf s o r efusa l s we r e d r i ed ove r n i ght , g r ound i n a hamme r mi l l f i t ted w i t h a c oa r s e s c r e e n and r efed the fo l l ow i ng day . Fe ed samp l es , i n a l l pe r i od s , we r e take n da i ly a nd bu lked ove r 2 weeks . Fe ed samp l e s wer e d r i ed , a s a b ove , i n o rder t o o bta i n mea n da i ly d ry ma tter i ntakes for each s he e p . Wat e r was p r ov i d e d ad l i b i t um i n 81 bucket s a t tached to the d i ge s tab i l i ty crat e s b u t wa ter i ntakes wer e n o t r e c o rded . The e xper i me nta l pr o t o c o l i nvo lved t h e e s t i ma t i on of woo l g r owth from c l i pped s h o u l d e r and m ids i d e sk in pat c he s , t h e d e t e rm i nat i on of b ody we i gh t by r egu lar fortn i gh t l y we i gh i ngs a nd the e s t i ma t i on of n i t r og en and d ry mat t e r d i ge s t i b i l ty of t he var i ous r a t i ons . 4 . 2 . 3 . Woo l g r owth rate R i gh t sh oulde r and r i gh t m i d s i d e w o o l pat ches we r e s horn a t the beg i nn i ng a nd e nd of the l a s t 4 weeks of e a c h per i od . Woo l was c l i pped fr om a squa r e pat ch (?lOcm by ?lO cm ) on t he r i ght s h o u lde r a nd m id s ide of each s h e e p . Os ter c l i ppers f i t t ed w i t h N o . O O O O b lades wer e used to r emove the w o o l g r own on the patch i n e ach per i od . A s i mi lar pat c h was opened on t he l eft s h ou ld e r and was i nt e nded t o capture data o n woo l produc t i on i n the trans i t i on per i ods . Th i s data was eventua l ly d i s carded as t rans i tory pe r i ods we r e c ons i d e r ed t o be d iffi c u l t t o i nt e rpr e t . A ls o , t h e t rans i t i o n be twe e n P 2 a nd P 3 was a n add i t i ona l 2 weeks l onge r than be twe e n Pl a nd P 2 , and s ome s he e p had d iffi c u l ty adjus t i ng t o a c hopped d i e t afte r p r es s-cake feed i ng . Two patches we r e c l i pped a t 2 o r 4 weekly i nt e rva l s to c o i nc i d e w i th un i nt e r upted woo l gr owth measurmen t d ur i ng t h e l a st 2 8 days on a par t i cu lar d i e t . On ly the four we ek samp l e s we r e p rocessed t o e s t ima te w o o l gr owth . The f i r s t two we eks of t h e s e pe r i ods a l l owed a br i ef t i me fo r woo l g r owth t o adjus t t o d i e tary c hange s . One s hou lder was a t a l l t i me s r e p l i ca t i ng the m ids i de 2 0 s amp l e . The d i me ns i ons of each pat c h wer e measured at e a c h c l i pp i ng us i ng Ve r n i e r ca l i pe rs w i t h e xt e nded arms . The l e ngth of e a c h s id e a nd the d iagona l of each patch wer e mea s u r ed a nd r e c o rded . The s urface of t h e pat c h was ca lcu lated a s t he s um of two t r i ang l e s . Th i s p r e caut i on was nece s s a ry a s s ome of the sk i n samp l e a r eas we r e r ema rkab ly non - r ectang u l a r . A l l woo l samp l es wer e s t o r e d i n l a be l led o pen e nve l op e s i n a c l i ma te c ontr o l l ed l abora t o ry ( 2 0? C , 6 5%RH ) and we r e c o nd i t i o ned for a t l e a s t 4 8 h o u r s pr i or t o we i gh i ng . Samp l e s wer e we i ghed , s c ou r e d by a four b owl and d e t e rge n t wat e r me thod wh i l e c onta i ne d i n i nd iv idua l f ine me s h bags , d r i e d i n a b l a s t of warm a i r , c o nd i t i oned?and we ighed a ga i n . to IG'f'o re9Qin Woo l g r owth r ates ( gr ea sy a nd c l e a n) wer e expr e s s e d a s mg pe r cm2 pe r day . Rams we r e n o t s h o r n a t the beg i n n i ng a nd e nd of t he 1 8 week t r i a l a s h ogget f l e ece we i ghts fr om t h e s e e xpe r i me nta l rams we r e r e q u i r ed by t he f l o ck manageme nt pr o t oc o l a nd s u b s e que n t s e l e ct i on . As t ot a l woo l g r owth dur i ng the e xpe r i me n t was n o t known i t was n o t p os s i b l e t o e xpr ess woo l g r owth i n t e rms of t o t a l gms p e r day . An a t t empt was mad e t o mea s u r e t he l e ngth of the p i l e o n woo l gr owth patches us i ng t he same Ve r n i e r ca l ope r s wh i c h mea s ur ed t h e pat c h a rea . T h i s pr oved unsucessfu l a nd t h e t e chn i que a nd meas ureme nts we r e a ba ndoned . 4 . 2 . 4 L ive we i ght L ive we i ght was measured a t for tn i gh t ly i nterva l s b e g i nn i ng w i th the f i r s t day of the t r i a l . To m i n imi ze l ive we i gh t e r r or s a r i s i ng fr om d iffe r e nc e s i n g u t f i l l , she e p we r e a lways we i ghed pr i or t o fee d i ng a t 0 8:0 0 hours . L ive we i ghts a nd s ubsequent mea s u r e s of l ive we ight ga i n i nc l ud e d 2 1 d iffe r enc e s i n f l e e c e c a r r i ed . As men t i o ned obove , i t was not poss i b l e t o pa r t i t i on t he tota l fl e e c e pr oduced i n e a c h pe r i od a nd s ubt ract t h i s i n o rder t o obta i n f l e e c e -fre e l ive we i ghts . Ga i ns a r e e xpre s s ed as abs o l ute c hange s over 2 8 day per i ods i n o r d e r t o mo r e c l ear ly d emons tra t e t he a s s oc i a t ed l ive we i gh t change s . 4 . 2 . 5 D i ge s t i b i l i ty of d ry matte r a nd n i t r ogen N i t r ogen and dry mat t e r d i ge s t i b i l i ty we r e d e t e rm i ned by t he t ota l c o l l e c t i on of fae c e s a nd ur i ne o n eve ry ram d ur i ng 1 0 -day p e r i od s i n t h e l a s t two weeks of e ach d i e ta ry p e r i od a s o ut l i ned previ o us l y . Fae c e s we r e c o l l e c ted da i l y , s t o r ed a t 5? c, bu lked over 5 days and then we i ghed . Two s ub? samp l e s , of a ppr o x i ma t e ly 2 0 0 g , we r e taken per s he e p from each of the two 5 -day s amp l e s . Sub-samp l e s we r e we i ghed befor e a nd aft e r d r y i ng at 1 1 0? F , for a ppr o x i ma t e l y 7 2 hour s , t o d e t er mi n e d ry mat t e r content . S i x t o s even s ma l l grab samp l e s from e a c h fr e s h tota l 5 -day o utput we r e poo l e d and fr e eze-dr i ed f o r subsequent n i tr ogen (N ) d e t e rm i na t i on s . Ur i ne was c o l l e c te d i nt o bucke ts conta i n i ng 1 0 m l of 2 . 0M H2S04. Ur i ne vo l ume was mea s ured da i ly a nd 1% of t h e da i ly output was samp l e d t o form a r epresentat ive 5 -day c ompos i te samp l e , a ls o for N d e t e rmi na t i on. Samp l e s of fe ed , ur i ne a nd faeces we r e a na lys e d for t o ta l n i t r og en by t he Kje ldah l met hod . 4 . 2 . 6 Ana lyt i ca l Me thods Data wer e ana l ys ed by ANOVA a nd MANOVA (Re peated Measu r e s Ana lys i s ) as d e sc r i bed prev i ous ly. Sever a l d iffer e nt c ovar i a t e s we r e used t o r emove c omp l i ca t i ng var i a b l e s . I n i t i a l we i ght a t the s ta r t of e a c h per i od was u s e d a s a c ova r i a t e i n t h e a s s e s sment of l ivewe ight ga i n . Al t hough s h e e p we r e fed c onstant amounts of feed d es i gned t o b e c omp l e t e l y c ons umed each day, s ome t i me s s i g n if i can t refus a l s we re c o l l e c t ed s uch that d ry ma tte r i nt a k e ( DMI ) was u s ed as a c ova r i a t e i n the ana lys i s of a ppar e nt d ry ma tte r ( DMDI G ) , a nd n i t r ogen ( ND I G ) , d i ge s tab i l i ty and woo l gr owt h . S im i lar ly , t ota l n i tr og en i ntak e was u s ed as a c ovar i a t e i n t h e ana lys i s of t o ta l u r i nary n i t r ogen e xc re t i on ( TUN ) . 2 2 Eac h pe r i od was a na lysed s e pa r at e ly a t f i r s t , the n a l l mea su r e s of woo l pr oduct i on , a l l measures of d i ge s tab i l i ty a nd a l l mea sures of l ivewe i gh t ga i n we r e comb i ned i n a r e peat ed measures ana l ys i s i n c l ud i ng d i e t effec t s ( even t h o ugh d i e t s we r e i n effec t for P 2 on l y . By ca r ry i ng d i e ts a s a d e s i gn fact o r i n MANOVA , t h e t r ue d i e t effec t i s a s s e ssed by the i n te ract i on of t i me w i th d i e t . W i t h s uc h s ma l l number s of s he e p p e r d i e t a nd l i ne ( 3 ) , i t may have b e e n poss i b l e that a n i ma l s we r e i neffec t ive ly randomi zed . A s i gn if i cant d i e t by t ime i nt e r a c t i on may be a mor e effec t i ve me thod of d e t e rm i n i ng non-pa ra l l e l pe rformance be twe e n tr u e t r eated a nd untreated pe r i ods . No f i xed effec t c or r e c t i o ns ( dam age , b i r th rank , r ear i ng r ank ) we r e app l i ed t o t he data a s t h i s would have r e s u l t ed i n s i ngu lar ma tr i c e s d u e t o l a r ge numbers of c la s s e s and ve r y few a n i ma l s per c l a s s . The mode l can be genera l i zed a s fo l l ows : M od e l 4 . 1: whe r e , y ? ? k = a n observat i on o n var i ous pr oduct ive t ra i ts of t he k th C or FW or ram hogge t i n s e l e c t i on l i ne j , ? = an unobse rved popu la t i on mean , a ? = the f i xed effec t of t h e i th d i e t b? = t he r egr ess i on o f y ? ? k o n Xl? ? k whe r e , Xl? ? k = t he o bse rved i n i t i a l we i gh t o f t h e i j k t h i nd iv i d ua l and , b 2 = t h e r e gr e s s i on o f y ? ? k o n x 2 ? ? k whe r e , x 2 ? ? k = the o bse rved dry mat t e r i nt a k e o f the i j k th i nd iv i d ua l , 1 ? = t h e f i xed e f f e c t o f t h e j t h s e l ect i on l i ne , and e ? ? k = the rand om res i dua l a s s o c i a te d w i th t he i j k th i nd iv i d ua l For P 2 , i n add i t i on t o the above , t h e mod e l i nc l uded f i xe d e f f e c t s o f d i e t a nd the i n terac t i on o f d i e t and s e l e c t i on l i ne . For P 2 a nd P 3 and mu l t ivar i at e a na l ys i s o f woo l g r owth , woo l gr owth i n P l r ep laced i n i t i a l we i ght a s a c ovar i a t e a nd dry matter i ntak e r e ma i ne d i n the mode l . 2 3 MANOVA o n acr oss per i od data u s ed the a bove mode l , w i t h t he i nc lus i on o f d i e t a nd d i e t X s e l e c t i on l i n e i nt e rac t i on , e xt e nded t o p -d i me ns i ona l s pa c e , whe r e p = 3 , f o r P l , P 2 a nd P 3 r e p l i ca t e s. 4 . 3 Re s u l ts a nd d i s cuss i o n T h e bags u s e d t o was h woo l samp l e s we r e f ound t o have t o o c o a r s e a weave t o e f f e c t ive ly c onta i n s h o r t c l i pped woo l f i br e s . As a l l samp l e s we r e was hed pr i or t o th i s d i s c ove ry , s i gn i f i ca n t l os s o f f i bres l i k e ly o ccured d ur i ng pr oces s i ng . The l os s r ate was d e t ermi ned by was h i ng c l ean , s o lvent e xtracted samp l e s a nd c ompar i ng samp l e we i ghts be f or e a nd a f ter . As the e f f e ct o f t h i s e r r or o n t h e e st i ma t e s o f c l ean woo l produc t i on o n i nd iv i d ua l s h e e p c ou ld n ot be d e te rm i n e d , greasy wool pr oduc t i on f i gur e s w i l l b e used i n a l l s ubs e quent r e s u l t s . C l ean woo l g r owth wi l l be d i s c u s s ed i n t h e t e xt . No s i gn i f i cant e f f e c t o f wool samp l e l ocat i on on woo l gr owth rate was f o und . I t was the n d e c i de d t o i nc lude data o n a l l 2 4 l oca t i ons as r e p l i c a t e s t o i nc r ease the powe r o f t e s t i ng f o r s e l e ct i on l i ne a nd d i e t d i f f e r e nce s . Wo o l g r owth mea ns i n Tab l e 4 . 1 a r e ave rage d a c r o s s l ocat i o n . L e a s t squa r e s means f or i n i t i a l we i ght ( IWT ) , l ivewe i ght ga i n ( LWG ) , g r easy woo l p r oduct i on ( GWOOL ) , DMD IG , da i ly ur i ne vo l ume ( UVOL ) , TUN , a nd NDIG by s e l e ct i on l i ne a nd d i e t ( P 2 o n ly ) , a r e p r e s e nt ed i n Tab l e s 4 . 1 a , b a nd c f o r P 1 , P 2 a nd P 3 , r e s p e c t ive l y . Shou lde r greasy woo l p r oduc t i on , by d i e t g r oup , i n P 1 , P 2 a nd P 3 a r e s h own i n F i gur e 4 . 1 . Shou lde r a nd m ids i d e r e s u l ts we r e s i m i lar . Sho u ld e r r e s u l ts we r e c h os e n f o r r e por t i ng a s t he d i me ns i ons o f t h e pat c h , a c r o s s samp l i ngs , r e ma i ned mor e c onstant than m ids ide pa tches a nd a ppea r ed t o b e a mor e d i s ce r n i ng mea s u r e o f woo l g r owt h . 4 . 3 . 1 Apparent d i ges t ive a b i l i ty N o s i gn i f i cant s e l e c t i on l i ne e f f e c ts o n t he a b i l i ty t o d i ge s t d r y ma tte r , o r n i t r og e n , we r e d emo ns t r a t ed i n a ny o f t h e p e r i od s s t ud i ed . Ind iv i dua l rams w i t h i n l i n e wer e a l a rg e r s ource o f var i a t i on than s e l ect i on l i ne . Th i s r e s u l t d o e s n o t a gr e e w i t h t h e e ar l i e r d i ge s t L b i l i ty t r i a l us i ng r ams on ad l i b i t um f e e d i ng o f cut pas t u r e ( McC l e l l and e t a l . , 1 9 8 6 ) . DMDIG i n t ha t t r i a l , c ou ld have be e n a f f ec t ed by f a i l ur e t o a ccount f o r a l l var i a t i on i n DMI, b e cause o f t h e r e l a t ive ly sma l l number o f an i ma l s p e r gr o up ( 8 ) a nd the r e l a t ive ly l arge r ange i n DMI ( 9 1 2 to 1 6 7 6 g/d ) . Rams we r e f ed e qua l ly i n t h i s t r i a l a nd r e fused f e ed was n o t s i gn i f i ca n t ly d i f f e re nt be twee n FW and C r ams , a s e xpected there we r e no d i f f e r e nc e s i n DMI o r d i ge s t ib l e d ry mat t e r i ntake be twe e n l i nes . The r e s u l t s o f the cur r e nt t r i a l agr e e w i t h the c o nc l us i o ns o f P i pe r a nd Do l l i ng ( 1 9 6 9 ) a nd Wi l l iams ( 1 9 7 9 ) who f o und that the a b i l i ty t o d i ge s t nutr i ents had not be e n a l t e r ed by 2 5 s e l e c t i on for f l e e c e we i ght i n Me r i nos . S i mi l a r ly , n o d iffe r e nc e s we r e found i n NDI G , i n a ny of t he pe r i od s , a nd the r e was no s i gn if i cant i n te ract i on be twe e n s e l e ct i on l i n e a nd d i e t d ur i ng P 2 . The a b i l i ty of F W rams t o r e s po nd t o add i t i ona l d i e ta ry s upp ly of ami n o a c i d s , i s t h e r efore n ot r e l a t ed t o t h e p r opor t i on of i nges te d nut r i e nts a bs o r be d a nd any s i g n if i ca nt d iffere n c e s i n woo l o r body gr owth a r e l ike l y a t t r i buta b l e t o d iffer e nc e s i n feed c onve r s i on eff i c i e nc y Dur i ng P 2 , d i et s d iffe r e d s i gn if i cant l y ( p< . 0 5 ) i n t h e d i g e s ta b i l i ty of n i tr o ge n , b u t not of d ry ma tte r . 4 . 3 . 2 L ive we i gh t a nd l ivewe i gh t ga i n La rge w i th i n l i ne var i a t i on i n l i vewe i g h t e x i s te d . The l i ne d iffe rences i n i n i t i a l w e i gh t a t t h e beg i nn ing of Pl, P 2 a nd P 3 we r e n o t s i g n if i cant l y d ifferent be twe e n l i n e s . To wha t e xt e nt t h e s e d iffer e nc e s r ef l e c t l ivewe i ghts under g ra z i ng c o nd i t i ons i s not known . FW h ogge ts have , h i s t o r i ca l ly , b een 2 kg heav i e r than C hogget s a t t h e t ime of h o gget s he a r i ng ( B l a i r , 1 9 8 6 ) . L ivewe i ght d iffe rences i n s ma l l i nd o o r t r i a l s a r e affe c t ed by samp l i ng . L ivewe i ght ga i n , was n ot s i gn if i ca n t ly d iffe rent be twe e n FW a nd C rams i n Pl and P 2 , but t he g r ea t e r l i vewe i gh t ga i n of FW h ogge ts i n P3 was h i gh l y s i gn if i cant . By the e nd of P 3 , FW rams we i ghed the same a s C rams , a s t hey had a t t h e s t a r t of the e xpe r i me n t . For unknown r e a s ons , FW rams ga i ned s l i gh t l y l e s s t han C rams d ur i ng P2 but the d iffe r e nc e was not s i gn if i cant . Compa r i s ons of l i vewe i gh t ga i n wer e l im i t ed by the r e s t r i c ted fe e d i ng r e g i me n emp l oyed i n t h i s tr ia l . The pr i ma ry o b j e c t ive be i ng to eva l ua t e d i ge s t ive a b i l i ty , i t was d e c ided t o opt for e qua l fe ed i ng w i th few r efusa l s . I n the t r i a l c o nducted i n 1 9 8 3 , ( McC l e l land e t a l . , 1 9 8 6 ) , FW a nd C r ams d i sp layed a s i mi lar r e la t i onsh i p be twee n DMI a nd l ivewe i ght ga i n . Supe r i o r g r owth rates i n P 3 can o n l y be a t t r i buted t o i mpr oved eff i c i e ncy o f c onver t i ng feed t o ga i n . 4 . 3 . 3 Ur i ne vo l ume 2 6 An unexpec t ed r e s u l t was t he i nc r eas ed ur i ne o u tput of FW rams r e la t ive t o c o n t r o l s . T h i s d iffe r e nce was s i gn if i ca n t a t p < O.Ol i n P 1 , a t p < ?DS i n P 2 a nd appr oached s i g n if i canc e i n P 3 ( p < 0 . 1 0 ) . A l t h ough wate r i ntake was n o t mea s ur e d , i t i s a s s umed that d iffe r e nc e s i n u r i ne o u tput r ef l e c t d iffe rences i n wat e r i ntake . The n i t r ogen concentra t i on of FW u r i ne was c o r r es po nd i ng l y r e duced s uc h t ha t t h e t o t a l u r i nary n i tr ogen e xc r e t i on was n ot s i g n if i cant l y d iffe re nt betwe e n genotype s . Gene t i c d iffe r e nc e s i n wat e r consumpt i on or t u rnover have b e en d ocumented i n t h e l i te ra t ur e . D o l l i ng and Ca r pen t e r ( 1 9 63 ) a nd McFar lane e t a l . , ( 1 9 6 6 ) have both r epo rt ed h i ghe r wat e r i nta k e s i n F + Me r i nos . McFa r lane e t a l . , ( 1 9 6 6 ) s ugges t ed that h i gh e r wat e r tur nover may c o r r e lat e w i t h t he u s e of wat e r i n c e l l u la r i ntermed iary metabo l i sm a s F+ s h e e p pr oduced 1 5% mor e woo l over t he same p e r i od i n h i s t r i a l . He pos t u la t e s a r e la t i onsh i p w i t h to ta l e n e r gy turnover a nd s ugge s t s t h e poss i b i l i ty of grea t e r r e na l output of wat e r i n F + s h e e p . Subsequent t o t h i s c u r r ent t r i a l , McCutcheon e t a l . , ( 1 9 8 7 ) d emons trated a h i ghe r c r ea t i n i ne c lea rance rate ( i nd i cat ive of greater g l omer u l a r f i l trat i on rate } i n FW c ompa r e d t o C rams . The b i o l o g i ca l s i gn if i cance of the s e d iffe r e nces r ema i ns unc l ea r . 2 7 4 . 3 . 4 Woo l g rowth Mea n s h o u l d e r r e s u l t s a r e ' pr e s e nted i n F i gure 4 . 1 . S i mi l a r t r e nd s we r e noted for m ids i d e samp l e s . Greasy woo l g r owt h of FW r ams was gr e at e r , i n a l l p er i ods . C l ean woo l gr owth was s i gn if i cant ly d iffe r e nt i n P 2 a nd P J . C r ams s h owed n o s i gn if i cant r e s ponse i n greasy o r c le a n w o o l g r owt h t h e case i n supp leme n ta t i on a s the r egr e ss i on o f P 2 wo o l gr owth rate on P l woo l g r owth rate was e qua l for a l l d i e ta ry l eve ls of case i n ( s l ope = 0 . 9 0 0 ? 0 . 2 9 7 ) . Amongs t FW r ams , t h e s e r egress i ons wer e h e t e r ogeneous w i t h s t e e pe r s l opes ( 0 . 2 6 1 ? 0 . 2 2 2 ; 0 . 6 5 2 ? 0 . 2 9 2 ; 2 . 3 2 6 ? 0 . 3 2 7 r e s pe c t ive l y ) a s t h e d i e tary l eve l of cas e i n i nc r eased fr om 0 t o 3 0 t o 6 0 g/d . I n P l , th e r e l a t i ons h i p of g r easy woo l g rowth t o DMI /k g0 ? 7 5 was pos i t ive i n FW rams but n ear z e r o i n C rams ( p< 0 . 0 5 ) . I n P 2 , a nd P 3 s imi lar r e la t i ons h i ps e x i s ted a nd appr oached s i gn if i ca nc e a t p = 0 . 0 6 . D iffe r e nc e s i n woo l pr oduct i on be twe en s h e ep o r be twe e n l i nes may b e due t o d iffe r e nc e s i n i ntak e , d i g e s t i ve a b i l i ty o r t h e t he eff i c i ency of c o nve r s i on of food t o woo l . Th i s e xpe r ime n t was c ons i s t e nt w i th the r e s u l ts of Wod z i ck a ? Toma s zewsk a ( 1 9 6 6 ) i n wh i c h R omne y sheep d iffer e d pr i ma r i ly i n t he eff i c i e ncy of c o nve r s i o n of fe ed t o woo l . I n Me r i no f l oc k s , t h e r e have bee n c ons i s t en t r e ports of h i gh e r eff i c i e ncy of conve r s i on o f food t o woo l and o n ly s porad i c r e po r ts of i nc r eased feed i nt a k e a s a r e sponse t o s e l e c t i on for f l e ece we i ght . As w i th Mer i no s e l e c t i on f l o c k s ( Wi l l i ams , 1 9 7 9 ) a nd w i t h i n? f l oc k R omney compar i s ons ( C l a r k e t a l . , 1 9 6 5 ) , d iffe r e nc e s i n wo o l pr oduct i on i nd i cated t ha t F W she e p we r e a b l e t o 2 8 d i r e c t a h i ghe r proport i on of a bs o r bed nutr i e nts t owards f l e e c e g r owt h , t h i s d ifference be i ng g r ea t e r at h i gh e r i nta k e s . S i mi la r pa r t i t i on i ng d iffe r e nc e s have be e n demonstrated be twee n Romney s h e e p w i t h h i gh o r l ow w i n t e r wo o l g r owth ( Hawke r a nd Cr os b i e , 1 9 8 5 ) . D ive r g i ng r e gr e s s i o ns of woo l g rowth o n i nt a k e betwee n F+ a nd C s he e p we r e r e po r t e d b y Ham i l ton a nd Lang land s ( 1 9 6 9 ) w i th i nc r ea s ed a l l owanc e s for she e p o n past ur e . The r e s po ns e s t o c as e i n supp le me ntat i on we r e n ot a s large a s t h o s e r e po r t e d i n Me r i nos ( Re i s , 1 9 7 9 ) . R e i s ( 1 9 7 9 ) a l s o s ugges t s that near max ima l i nc r ea s e s i n wo o l g r owth rate a r e obta i ne d a t s uppl e me nta t i ons o f 1 2 0 g/d . Se l e ct i on l i ne by d i e t i nt e ract i ons e x i s ted as C rams r e ce iv i ng 30 o r 6 0 g/d of c as e i n d i d n o t s i gn if i cant l y outperform the 0 g/d c ontr o l s . FW rams o n case i n d i e ts i nc r eas ed woo l g r owth r e la t ive t o 0 g/d c ontro l s . I n t h i s s tudy, cas e i n supp l eme n tat i on was tes ted over wi n t e r a nd s eve r a l a u t h o r s have shown t ha t t h e a b i l i ty of R omne ys t o r e s p ond t o i nc r ea s ed nutr i t i on i s s ubs tant i a l ly r educed over w i nt e r ( Sumner , 1 9 7 9 ; Hawke r a nd Cr o s b i e , 1 9 8 5 ) . The e xt en t t o wh i c h i nher d iffe r e nc e s i n t he s e a s ona l cyc l e of woo l gr owth have be e n c onfounded w i t h s e l e ct i on l i ne c ompa r i s ons i s not k nown . Tab l e 4 . 1 L east squa r e s means of performanc e t ra i ts of FW and C rams fed l uce r ne d i ets . 2 9 a . Pr e l im i na ry per i od , P1 ( l O O Og/d l uc e r ne p r essca k e ) Var i a b l e c FW s i g . = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = I WT ( kg ) 3 0 . 1 ? 0 . 9 2 9 . 3 ? 1 . 4 2 ns L WG ( k g ) 1 . 2 6 ? . 2 3 1 . 2 0 ? . 2 6 ns GWOOL ( mg/cm2/d ) 1 . 3 1 ? . 0 6 1 . 5 0 ? . 0 9 * DMD I G (% ) 5 8 . 4 ? . 4 5 7 . 5 ? . 3 ns NDI G (% ) 6 6 . 6 ? . 7 6 5 . 8 ? . 8 ns UVOL ( ml/d ) 1 3 5 5 . ? 9 6 . 2 1 3 3 . ? 2 8 7 . * * TUN ( g/d ) 7 . 5 ? 0 . 1 7 . 4 ? 0 . 4 ns = = = = = = = = = = = = = = = = = = = = = = = = = = = = = == = == = == = = = = = = = = = = = = = = Tab l e 4 . 1 b . Chopped l u c e rne ( 1 4 0 0g/d ) , P 3 Var i a b l e c FW s i g . = == = = = = = = = = = = = = = = = = = = = = = = = = = = == == = == = == = = = = = = = = = = = = I WT ( kg ) 4 0 . 6 ? 0 . 7 3 8 . 8 ? 0 . 9 ns L WG ( k g ) 1 . 4 2 ? . 4 1 3 . 2 3 ? . 3 8 * * * GWOOL ( mg/cm2/d ) 2 . 0 2 ? . 1 4 2 . 5 6 ? . 11 * * DMD I G (% ) 5 9 . 4 ? . 3 5 9 . 6 ? . 4 ns ND I G (% ) 6 9 . 1 ? . 5 6 9 . 9 ? . 4 ns UVOL ( ml/d ) 1 5 2 7 . ? 2 1 0 . 2 0 9 6 . ? 2 3 0 . p < . 1 0 TUN ( g/d ) 9 . 5 ? 0 . 2 9 . 1 ? 0 . 4 ns = == = = = = = = = = = = == == == = = = = = = = = = = = = = = = = = = == = = = = = = = = = = = = Tab l e 4 . 1 c . P 2 ? Forma lde hyd e protected case i n Var i a b l e c FW = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = ? = = I WT ( k g ) 3 4 . 6 ? 0 . 6 3 2 . 7 ? 0 . 9 LWG ( k g ) 1 . 6 1 ? . 4 1 0 . 6 0 ? . 3 8 0 GWOOL ( mg/cm2/d ) 1 . 6 2 ? . 4 7 1 . 6 8 ? . 8 3 g/d DMD I G ( % ) 5 9 . 5 ? . 3 6 0 . 8 ? . 4 NDI G ( % ) 6 7 . 2 ? . 7 6 8 . 1 ? . 6 UVOL ( ml/d ) 1 4 6 3 . ? 2 1 0 . 2 5 6 7 . ? 2 3 0 . TUN ( g/d ) 7 . 0 ? 0 . 6 8 . 0 ? 0 . 7 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = I WT ( k g ) 3 4 . 2 ? 0 . 7 3 4 . 2 ? 0 . 7 LWG ( k g ) 1 . 4 2 ? . 4 1 1 . 6 3 ? . 4 2 3 0 GWOOL {mg/cm2/d ) 1 . 9 1 ? . 7 6 1 . 8 6 ? . 4 5 g/d DMD I G (% ) 6 3 . 4 ? . 3 6 3 . 3 ? . 3 ND I G (% ) 7 1 . 9 ? . 5 7 1 . 0 ? . 4 UVOL ( ml/d ) 1 5 2 4 . ? 2 1 0 . 2 1 3 8 . ? 2 3 0 . TUN ( g/d ) 1 0 . 2 ? 0 . 7 9 . 9 ? 0 . 4 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = I WT ( k g ) 3 5 . 1 ? 0 . 7 3 3 . 4 ? 0 . 9 LWG ( k g ) 1 . 9 0 ? . 2 3 3 . 2 . 3 8 6 0 GWOOL (mg/cm2 /d ) 1 . 5 0 ? . 9 5 2 . 3 7 ? . 4 2 g/d DMD I G (% ) 6 3 . 6 ? . 3 6 1 . 9 ? . 7 NDI G (% ) 7 4 . 1 ? . 5 7 3 . 5 ? . 4 UVOL ( ml/d ) 1 9 8 5 . ? 2 1 0 . 2 0 0 4 . ? 2 3 0 . TUN ( g/d ) 1 3 . 4 ? 1 . 2 1 1 . 8 ? 0 . 6 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = ?30 ea ? ? 5 2.5 "" en ? 2 0 ? ? ...., ;: 0 1.5 ... en 0 ? 1.0 P 1 3 0 CASE I N G ROU P ( g day ) E O P2 P3 C O N T R O L t]l 30 P 1 P2 P 3 F L E E C E WE I G HT Figure 4 . 1 Mean s ho u lder greasy woo l g r owth of fleece we i g h t s e l ected ( FW ) and c ont r o l ( C ) rams dur i ng uniform feed i ng ( lk g/d ) in P l , cas e i n s upplemen ta t i on i n P 2 , a nd un iform feed i ng ( 1 . 4 k g/d ) i n P 3 . ( D i e t d e ta i l s may b e found i n the t e xt ) 31 4 . 4 Conc l us i ons The r es u l ts s ugge s t t hat t he adva ntage of FW over c rams i s due , i n par t , t o d iffe rences i n the a b i l i ty t o d i r ect absorbed nutr i ents t owards woo l gr owth . Th i s d iffer ence become s mor e evide nt w i th h i gher fe ed i ng leve ls . The C f l ock adva ntage i n di3esl'i??e ab i l i ty r e po r t ed p r ev i ous ly , was n ot d emo ns trated i n t h i s t r i a l . The poss i b i l i ty that d iffer e nces in "forag i ng a b i l i ty " , s e l ec t iv i ty or other adapt ive characters may ope rate und e r pas ture cond i t i ons cannot be i gno r ed . The performa nce of these a n ima ls u nd e r pas tur e cond i t i ons needs t o be mor e fu l ly e xp l o r ed e s pe c ia l ly w i th r efe re nce t o pat t e r ns of i ntake , woo l g rowth a nd l ive we i ght ga i n over the i r f i r s t product ive year . Further i nve s t i ga t i ons i nt o wat e r me tabo l i sm of FW and C s he e p may a l s o be warranted g iven cons i s tent d iffer ences i n da i ly u r i ne output r e ported h e r e . 3 2 S EASONAL I TY OF WOOL GROWTH 5 . 1 I nt r oduc t i on and r ev i ew of l i t e ra ture A l tho ugh i t has l ong bee n r e c ogn i z ed t ha t woo l g r owth i s n ot u n iform thr oughout the yea r , t h e var i ous factors wh i c h c ontr i bute t o the o bserved pat t e r n have ye t t o b e fu l l y unrave l l ed. I n t he a bs e n c e of c on t r o l l e d e nvi r onme nt s i t was d i f f i c u l t f o r ear l y wo r k e rs t o s e pa rate the effec t s of s e a so na l pas ture g r owt h , c ha ng i ng t emperatur e , dayl e ng th , p r egna ncy and l acta t i on a nd the effec t of shear i ng i t s e lf o n t h e observed woo l gr owt h pat t e r ns . The a nnua l r hythm of woo l gr owth d i s p laye d by mos t mod e r n b r e eds o f s h e e p i s l a rge l y a ve s t i ge of t he ar cha i c mec ha n i s m o f f le ec e s hedd i ng . Th i s r hythm o f woo l/ ha i r gr owth i s now k n own t o b e k ept i n p ha s e w i th s eason by photope r i od i c c ontro l i n s h e e p a nd in o ther mamma l s (s uch a s m i nk , d e e r , fe rr e t s , vo l e s a nd hams te r s ) wh i c h e xh i b i t c ha nge s i n the i r pe l age a nd r e pr od uc t ive act ivi ty a c cord i ng t o the s e a s on . B r e eds of s h e e p , a s i n s tra i ns of o th e r mamma l s , d iffer i n t he i r r e s ponse t o photope r i od i c , nutr i t i ona l and t h e rma l s t i mu l i . The s e , a nd d iffe r e nc e s i n f l e e c e charact e r i s t i cs be twe e n a n i ma ls , c ontr i bute t o t he g ene t i ca l ly d e t e rmi n ed c omponent of the s eas ona l c yc l e . The phys i o l o g i ca l mechan i s ms by wh i c h photope r i od e x e r t s i t s c ontr o l o n t h e r hythm of woo l gr owt h a r e poor ly und e r s t o od . As s oc iated mecha n i sms i nvo lved i n the contr o l o f r eproduct ive cyc l e s have o n l y r e cent ly b een e l uc i da t ed . Evidence i n both f i e lds wou ld i mp l i ca t e t he p i nea l g la nd a nd i ts ef fects , v i a l i ght/da r k c ontr o l l e d s ecre t i ons , o n t h e a c t i on o f var i ous e ndocr i ne o rgans a nd the ir s ubsequent effect s o n wo o l g r owth and r e pr od uc t i on . 3 3 The s easona l pa t t e r n o f wo o l g rowt h i s pe r t i nent t o the c ompa r i s on o f u ns e l ected a nd f l eece we i gh t -se l e ct ed s h e e p a s i t r e lates t o : s ta p l e s t r e ng th ; pos s i b l e s e a s o na l d i f f e r e nces i n t h e a b i l i ty t o d i scr im i na t e be twe e n g e n otype s ; t h e s e a s o na l i ty o f r e product i o n ; s e a s o na l pa t t e r ns o f f e ed i nt a k e a nd body gr owth a nd t h e a b i l i ty o f a n i ma l s t o r e s pond t o n u t r i t i ona l fac t o r s . 5 . 1 . 1 Nut r i t i ona l a nd c l i ma t i c e f f ects 5 . 1 . 1 . 1 H i s to r i ca l Wod z i cka ( 1 9 6 0 ) s umma r i zed e a r l y Ger ma n wor k wh i ch e s tab l i s hed t ha t woo l g r o wt h was great e s t i n t h e s umme r mon t hs a f t e r spr i ng s hea r i ng . Hence , i t was t hought t hat t h e i r regular i ty o f woo l g r owt h was a s he a r i ng , r ather t han a s easona l , e f f e c t . O t he r wor k e r s ( Ha rdy a nd Ten nys o n , 1 9 3 0 ; Burns 1 9 3 la , b ; Due r d e n a nd Ma re , 1 9 3 1 ) had pr e v i ous l y c o n f i rmed seas ona l t r e nd s b y mea sur i ng l ength gr owth r ate . S e a s o na l t r e nds i n f i b re d i amet e r we r e a ls o obs e r ved ( Ha rdy a nd Tennys o n , 1 9 3 0 ) . I n t he s e s t ud i e s , n u t r i t i on was l a rge ly uncontr o l l ed . Ga l p i n ( 1 9 4 8 ) r e po r ted s ubstant ia l s ea s o na l d i f f e r e nc e s i n m i d s i d e pat ch pr oduct i on i n Romn ey s he e p b u t d id n o t r e po r t f e ed i ng leve l s . W i l s on ( 1 9 3 1 ) a nd B e l l e t a l . ( 1 9 3 6 ) r e c og n i zed t h e c o r re lat i on be twe e n woo l g r owt h r a t e a nd f e ed a va i la b i l i t y . Ewes wer e a l s o o bs e r ved t o have r educed woo l g r owth dur i ng l a c ta t i on ( Be l l e t a l . , 1 9 3 6 ) . I n Med i te r ranean e nv i r onments , whe r e f e ed was o f t e n super i or i n w i n t e r mon t hs , the r hythm o f woo l g rowt h was n o t s hown ( Fr a ze r , 1 9 3 1 ) . Canad i a n work e r s t hought t ha t t h e b i t t e r c o ld o f t he Canad ian w i n te r m i g h t be t he cause o f l ow wi n t e r produc t i on ( Bows tead a nd La r os e , 1 9 3 8 ; Lar ose a nd Tweed i e , 1 9 3 8 ; 3 4 S a c kv i l l e a nd Bows tead , 1 9 3 8 ) . They k e pt Rambo u i l 1e t e we s i n h e a t ed a nd unheated pens f o r u p t o 3 months but we r e u na b l e t o a l te r w i n t e r produc t i on . As t he f eed i ng l e ve ls we r e not s tated , i t i s d i f f i c u l t t o d raw d i r ect conc l u s i ons a b ou t t he e f fec ts o f tempe rature ( va r y i ng as muc h a s 2 9 ?C b e t we e n pens ) f r om t h i s wor k . 5 . 1 . 1 . 2 S he a r i ng Respons e s Al t h o ugh ear l y r es ea rche r s t hought t hat s hear i ng had a d i r e c t e f f ec t on woo l g rowt h , i t has s i nce be e n d e mo n s t r a ted t ha t t h e s hear i ng r e s ponse i s med ia ted t h r o ugh a c ha nge i n i ntake f o l l owing s hea r i ng . Ea r ly obs e rva t i ons by Car t e r ( 1 9 4 4 , unpub l i s hed da ta ) s howed t hat a ppe t i te i nc r e a s ed mar k e d ly a f t e r s he a r i ng a nd d ec l i ned s te ad i l y u nt i l t h e next s hear i ng whe n s h ea r i ng . I n o ther s t ud i e s ( Da ly a nd Car te r , 1 9 5 5 ; S c h i nc k e l , 1 9 6 0 ; Wodz i ck a? 1 ?60j Whee l e r , Reard o n a nd Lambou r ne , 1 9 6 3 ; We s t o n , 1 9 7 0 ; Bo t t om1ey, 1 9 7 9 ) t he i nc r ease i n i ntake pos t ? s hea r i ng has b e e n we l l d ocume nt ed . Wodz i c ka -Tomasews ka ( 1 9 6 0 ) was una b l e t o s how g r ea t e r a n nua l woo l gr owth i n f r e quent l y s h o r n s h e ep but McGu i r k e t a l . ( 1 9 6 6 ) a nd B i gham ( 1 9 7 4 ) d emonst r a ted that a nn ua l woo l p r oduct i on i ncreased a s s he a r i ng f r equency i ncreased . B o t t omley ( 1 9 7 9 ) r ev i ewed t h e f actors a f f ect ing t h e e xte n t o f t h i s p o s t - s hea r i ng r i s e i n i nt a k e . Whe e l e r e t a l . ( 1 9 7 7 ) c ompa r ed woo l gr owt h i n c ove r ed a nd uncove red s he e p a nd s ho wed t ha t a t h e rmo- regu lato ry r esponse , r ather t han a r e s ponse t o s he a r i ng pe r s e . was r e s po ns i b l e f o r i nc re a s ed woo l gr owth a f t e r s hear i ng . 5 . 1 . 1 . 3 Nutr i t i o n S i nce t h e f i r s t observa t i ons i n t he 1 9 3 0 ' s , nume r ous a u tho rs have t i ed the va r i ab i l i ty i n s e a s o na l woo l gr owt h t o s e a s o na l var i a t i on i n pas tu r e ava i l ab i l i ty ( Ma r s t on , 1 9 4 8 ; 3 5 S c h i nc k e l , 1 9 5 6 ; Hutc h i ns o n a nd P o r te r , 1 9 5 8 ; Roe e t a l . , 1 9 5 9 ; S t ewar t e t a l . 1 9 6 1 ; S ha r k ey e t a l . , 1 9 6 2 ; Wi l l i ams a nd S ch i nc k e l , 1 9 6 2 ; Ar no ld e t a l . , 1 9 6 4 ; McFa r la ne , 1 9 6 5 ; Re i s a nd W i l l i ams , 1 9 6 5 ) . Howeve r , Whe e l e r e t a l . ( 1 9 6 3 ) we r e una b l e t o d emons tra te a c l ear r e l a t i o ns h i p be twe e n past u r e a va i la b i l i ty a nd d i ge s t i b l e o r ga n i c mat t e r i ntake i n t he Me r i no s t h ey s t ud i ed . Notwi ths ta nd i ng t h i s r es u l t , i t s e ems t ha t t h e woo l gr owth r hythm d i s p la ye d by Mer i nos i s mor e s e ns i t i ve t o nutr i t i o n t ha n the r hythms o f o ther breeds i n wh i ch a l te r ed a n nua l i nt a k e pa t t e r ns do n o t r emove or r eve r s e t he n o rma l pat t e r n of woo l gr owt h ( Co op , 1 9 5 3 ; W i ldma n , 1 9 5 7 ; S t o r y a nd Ross , 1 9 6 0 ; D oney and Smi t h , 1 9 6 la ; S l e e a n d Car te r , 1 9 6 1 ; Be nnett e t a l . , 1 9 6 2a , b ; W i l l i ams , 1 9 6 4 ; H utch i ns o n 1 9 6 5 ; R oss 1 9 6 5 ; D oney 1 9 6 6 ; Doney a nd Ead i e 1 9 6 7 ; Doney a nd Evans , 1 9 6 8 ; 1 9 7 0 ) . Ryd e r ( 1 9 56 ) c on c l uded t hat t h e s t i mu l us f or f i br e s hedd i n g i s s eas ona l r a t he r t ha n nut r i t i ona l i n Mas ham s h e ep a l though Lyne ( 1 9 6 4 ) was a b l e t o i ncrease s hedd i ng i n Mer i nos f ed a p o o r d i e t . S le e ( 1 9 6 5 ) s ho we d t ha t a l though poor n u t r i t i on c o u ld i mpede s hedd i ng i n W i l ts h i r e Horns , adequate nutr i t i o n me r e l y a l l owed s hedd i ng t o p r oceed und e r t h e i n f l ue nc e o f o t he r f actor s . Ar n o l d e t a l . ( 1 9 6 4 ) a nd S umne r a nd W i c k ham ( 1 9 6 9 ) f ound t hat h i gh e r s t ock i ng r a t e s accentuated t h e r hythm of woo l g rowt h t h r o ug h a g r eate r a nd pr o l onged w i n t e r d e press i on . P r e gnancy a nd l ac tat i on , t h r ough t h e i r h i gh nut r i t i ve dema nds a nd d r a i ns on body r e s e rves , a l s o red uce w i nter woo l g r owth f u r t he r a nd postpone the r i s e i n s p r i ng ( Coop , 1 9 5 3 ; S l e n a nd Wh i t i ng , 1 9 5 6 ; S tory a nd R os s , 1 9 6 0 ; S t ewa r t e t a l . , 1 9 6 1 ; R o s s , 1 9 6 5 ; Hawk e r a nd K e nnedy , 1 9 7?) . The e f f e c t i s g r ea t e r i n e we s bea r i ng mor e t h an one o f fs pr i ng ( S l e n a nd Wh i t i ng , 1 9 5 6 ; R os s , 1 9 6 5 ) That the a n nua l r hythm o f woo l g r owth i n many b r e eds i s n o t 3 6 r emoved by cons tant f e ed i ng , o r f eed i ng t o e qua l body we i gh t , i nd i ca t e s i ts c o n t r o l by non-nut r i t i on a l f a c t or s . N utr i t i on mod i f i e s the i nh e r e n t pa t t e r n e s ta b l i s he d by o t h e r e nv i r o nme nta l a nd p hys i o l og i ca l f actor s . 5 . 1 . 1 . 4 Tempe ra t u r e Fer gu s o n e t a l . ( 1 9 4 9 ) s t ud i e d t h e woo l g r owth r a t e o f Camd e n Par k Me r i nos a nd Co r r i eda l e s g i ve n a c o n s tan t i nt a k e o f a u n i f orm d i e t a nd f ound a pos i t i ve a s s oc ia t i on b e twe e n e nv i r o nme nta l a i r t empe r a t u r e a nd f i br e l e ngth g r owt h r a t e . They s ugge s ted t ha t vas od i l a t i on caused i ncreas ed b l o od f l ow t o the s k i n wh i c h i nc r e a s ed woo l g r owth i n wa rme r t empe ra t ur e s . Fe r gu s o n ( 1 9 4 9 ) i n a n e xt e ns i on o f t h i s i d e a , pe r f ormed un i la t e ra l t h o rac i c s ympa t he c t om ies o n s he e p t o d e s t r oy t he vas ocons t r i c t i on r e s ponse . I ncreas ed woo l g r owt h o n the ope ra t ed s i d e was e l i c i ted f o r u p t o 1 0 wee k s . Coop ( 1 9 5 3 ) and Coop a nd Ha r t ( 1 9 5 3 ) , a l s o us i ng e we s on c o n t r o l l ed f e ed i ng , f ound t ha t s easona l c hanges i n l e ng t h a n d d i amet e r we r e n o t a f f ec ted b y k e ep i ng ewe s i n a r oom 1 3 oF above o uts i d e t empe r a t ur e d u r i ng w i n te r . They d i d n o te t he c o r r e la t i on b e twe e n o u t s i d e t emperature a nd d ay l e ng th as a poss i b l e f o rce be h i nd s eas o na l var i a t i on in woo l g rowt h . Wod z i ck a ( 1 9 6 0 ) s uppo r t ed t he r e s u l t o f Fergus o n e t a l . ( 1 9 4 9 ) i n the a bs e nce o f a d emons t ra t i ve e f f e c t o f photoper i od i n h e r expe r i me nt . Mor r i s ( 1 9 6 1 ) r e ve r s ed t he a nnua l t emperatu r e cyc l e a nd f ound no e f fect o n t he woo l g r owth cyc l e i n R omney Ma r s h s h e ep . Benn e t t e t a l . ( 1 9 6 2 a , b ) , us i ng S o u t hdowns a nd Me r i nos , f o und no obv i ous e f f e c t s o f t emperature o n woo l gr owt h , p r ov i d i ng t hat t h e s h e e p had adequa te woo l cove r . Al t hough woo l gr owt h i s n o t und e r the contr o l o f t empe rature , s ome l oca l e f f ects o f tempe ratu re , a s e v i de nced on f r e quent l y c l i pped pat che s , may e x i s t . 3 7 D i f f e r i ng woo l g r owt h o n c l i pped pa tches e xposed t o na tu r a l o r i nduced c o l d cond i t i on s ( Be n n e t t e t a l . , 1 9 6 2 ; Wod z i c k a - Tomasews ka , 1 9 6 6 ; Doney a nd G r i f f i t hs , 1 9 6 7 ; Wod z i c k a - Tomasews ka a nd B i gham, 1 9 6 8 ; Downe s a nd Hutch i ns o n , 1 9 6 9 ; Lyne e t a l . , 1 9 7 0 ) we r e d ue t o a s h o r t t e rm reduc t i on i n l ength gr owth r a t e wh i l e f i br e d i amet e r was l a rge l y u na f fec ted . I n mos t o f t h e s e s t ud i e s t h e s u r r ound i ng p i l e was k e pt s h o r t o f f e r i ng m i n i ma l p r o t e c t i on t o t h e c l i pped pa tc h . S ha r k ey e t a l . ( 1 9 6 2 ) o f f e r ed n o e xplana t i on a s t o why t h e ave rage d i ame t e r o f c l i pped samp l es was 2 mi c r o n s g r ea t e r than ad j acen t l o ng s ta p l e s i n Cor r i eda l e s . Ruda l l ( 1 9 3 3 ) noted i nc rease ha i r n e s s a f t e r s hear i ng i n Romney lambs wh i c h a ppea red t o b e l i n k e d t o l oca l tempe rature e f f ec ts . Coop ( 1 9 5 3 ) f ound n o d i f f e r e nce b e twe e n ad j acent patches c l i pped e i t h e r every mon t h o r e ve ry 3 months . Downes a nd Lyne ( 1 9 6 1 ) , u s i ng r ad i ograph i c t e c h n i ques , showed t hat c l i pp i ng p e r s e . h ad n o e f f e c t o nc e t empe rature e f f ec ts we r e m i n i m i z ed . O ther r e s ea rch e r s h ave f ound n o e f f e c t o f f r eque n t c l i pp i ng o n woo l g r owt h ( Do n ey a nd Smi t h , 1 9 6 la ; B i gham 1 9 7 4 ) o r i n b l o od f l ow t o t h e s k i n ( S etche l l a nd Wa i te s , 1 9 6 5 ) . B i gham d o es n o t c omme n t on the contrad i c t i on o f h i s ( 1 9 7 4 ) r e s u l t s w i t h t h o s e o f a n ear l i e r s t udy ( Wodz i c k a -Tomasewska a nd B i gham 1 9 6 8 ) . The ear l i e r s t ud y was done i nd o o r s under c ons tant f e e d i ng , whe reas the l a t e r wo r k was d o n e outdoors und e r f r e e g raz i ng c o nd i t i ons . Unde r ad l i b i t um f eed i ng , s h e e p a r e a b l e t o ma i nta i n t he rmoneutra l i ty by i nc r eas i ng i nta k e a f t e r s hear i ng . L ocomot i on a l s o he l ps t o ma i nta i n d e e p body and per i phe ra l t i s s ue tempe rature . 5 . 1 . 1 . 5 P h o tope r i od Ear ly wor k e s ta b l i s hed t h a t daylength r egulated s easona l s hedd i ng a nd coa t changes i n t he f e r r e t ( B i s one t te 1 9 3 5 ) a nd o the r mamma l s such as t he s i l ve r f ox , m i n k , wea s e l a nd 3 8 h o r s e ( B i s o ne tte a nd Wi l s o n 1 9 3 9 , Bas s e t t e t a l . 1 9 4 4 , B i s on e t t e a nd Ba i l e y 1 9 4 4 , Bur k hardt 1 9 4 7 , Hammond 1 9 5 1 , 1 9 5 2 1 9 5 3 ) . Yea tes ( 1 9 5 4 a , b ) r e v i ewed much o f th i s e a r l y wor k and i n l a t e r e x pe r i me nt s ( Yeates 1 9 5 5 , 1 9 5 7 ) s howed that mou l t i ng cyc l e s i n ca t t l e we r e assoc i a t ed wi t h dayl e ngth . I n s he e p , as men t i o ned p r e v i ous ly , Coop a nd Ha r t c ooperated o n one o f the f i r s t woo l g r owt h a nd photope r i od e x pe r i me nts . A numbe r o f r e po r t s wer e pub l i s he d ( Ha r t 1 9 5 3 ; C oop 1 9 5 3 ; Coo p a nd Ha r t 1 9 5 3 ) s howi ng that we t Cor r i eda l e e we s e xposed t o 8 h o u r s o f l i gh t ( L ) : 1 6 h o u r s o f dar k ( D ) g r ew mo re woo l i n w i n t e r a nd s pr i ng than ewe s und e r na tur a l l i ght o n a s im i l a r d i e t . The r hythm o f woo l g r owth i n t h e c ons tant daylength g r o up pe r s i s ted f o r ove r 2 yea r s . Ass umi ng t ha t t h e e ye was t he r ecept i ve o rga n , Har t ( 1 9 5 5 ) h ooded s he ep f o r a pe r i od o f two yea r s . The a n i ma l s we r e s t i l l s ub j e ct ed t o t he a nnua l t emperature r hythm but t h e r hythm o f woo l g r o wt h d i s s appeared a f te r 1 . 5 yea r s . W i l dman ( 1 9 5 7 ) s u b j e ct ed rams a nd we the r s t o a n 8 L : 1 6D c o ns tant r eg i me f o r a bout 2 yea r s a nd found i nc reased p r oduc t i on i n a l l s eas ons , wh i ch i s i n c ontra s t t o p r ev i ous a nd s ubsequen t wor k by o t h e r s . Mo r r i s ( 1 9 6 1 ) was a b l e t o r e ve r s e the a nnua l cyc l e o f woo l g r owt h by acc e n t uat i ng a nd r e ve r s i ng dayle ngth . The amp l i tude o f s easona l woo l g r owt h was i ncr eased i n t h e a ccen tua t ed cyc l e . The f a c t that 2 yea r s we re r equ i r e d t o r eve r s e the r hythm was used t o e x p l a i n the f a i l u r e o f Wod z i ck a ( 1 9 6 0 ) t o a l t e r woo l gr owth d u r i ng 1 2 mon t hs o f c o ns tant dayle ngt h . I n a n e xtens i on o f h i s e ar l i e r wor k , Har t ( 1 9 6 1 ) i nc l uded dry ewes i n the 8 L : l 6 D g r o up , hooded ewe s , e we s und e r c o n t i nuous l i ght a n d ewe s o n a 2 L : 4 D cyc l e . Cont i nuous l i ght , supp l i ed by a r t i f i c i a l l i ght i ng , had no e f f e c t on the wo o l gr owth r hythm, sugge s t i ng t hat shee p cou l d d i s t i nqu i sh be twe e n l i ght o f va ry i ng i n t e ns i ty . Fa i l ure t o p r ov i d e adequate i nt ens i ty o f l i ght may a l s o have caused mi s l ead i ng 3 9 r e s u l t s i n o the r s tud i e s . The l a t e n t pe r i od o f r e s ponse t o o t h e r t r e atme n t s was 3 - 5 mon t hs a nd ewe s o n the 2 L : 4 D s ched u l e r e s ponded qu i ck e r than those o n 8 L : l 6 D , e ve n though both gr oups r ece i ved e qua l da i ly h ours of l i gh t a nd dar k . Ha r t ( 1 9 6 1 ) s ugges ted t ha t t h e t hyr o i d g l a nd may be i nvo l ved i n the r e g u l a t i on o f woo l growt h . O the r wor k e r s ( Be nn e t t e t a l . 1 9 6 2 a , b ; Ha r t e t a l . 1 9 6 3 ; W i l l i ams 1 9 6 4 , Hutc h i ns o n 1 9 6 5 ) c on f i r med t h e r e s ponse o f woo l g r owt h t o phot o pe r i od i c change s . D i f f e r e nces i n l i ght i nt e ns i ty we r e be l i e ve d t o a f f e c t t h e s hape o f t h e a tta i ned c urve a nd t h e i mmed i acy o f i ts e s t ab l i s hme nt . R ouge o t ( 1 9 5 7 , 1 9 6 1 ) s h owed that t he s hedd i ng a nd gr owth cyc l e s o f t h e k emp f o l l i c l e s o f L imous i ne s he ep c o u l d be read i ly c o n t r o l l e d by dayl e ngth . R ev i ews of photoper i od i c e f f e c t s o n woo l g r owth a nd s hedd i ng a r e g i ven by Hutc h i ns o n ( 1 9 6 5 ; 1 9 7 6 ) , Ryder a nd S t e phenson ( 1 9 6 8 ) , Nagor?a ( 1 9 7 9 ) a nd Pana r e t t o ( 1 9 7 9 ) . Mor e r e ce n t l? Ryder a nd L i nco l n ( 1 9 7 6 ) s t ud i ed t he e f f e c t o f a l t e r na t i ng per i od s o f s h o r t ( 8 L : l 6 D ) a nd l o ng ( 1 6 L : 8 D ) days o n f l eece gr owth a nd shedd i ng i n S oay sheep . De l ays i n r e s pon s e we r e 2 - 3 months a f te r chang i ng dayl e ng t h . E i gh t t o 1 2 we e k s o f l on g days was s u f f i c i e n t t o act i va t e f o l l i c l e s i n a l l a n i ma l s , whe r eas 4 wee k s exposure t o s ho r t days was e nough t o r ed uce f o l l i cu l a r act i v i ty . L i nc o l n e t a l . ( 1 9 8 0 ) f o und b o th woo l a nd h o r n gr owt h i n t h i s b reed t o be under photoper i od i c c ontr o l . K a y a nd Ryder ( 1 9 7 8 ) were a b l e t o e l i c i t a t w i ce a nnua l s hedd i ng a nd regr owt h of ha i r i n R ed d e e r e xposed t o a s i x mon t h cyc l e o f day l e ngt h . S ho r t e n i ng o f the cyc l e was who l ly brought about by reduc i ng t h e r e te n t i on t ime o f t h e mat u r e coat . I t has be e n we l l d emo ns trated , b oth i n s h e ep a nd i n o t h e r mamma l s t ha t phot ope r i od i s t he ce n t r a l r egu lator o f woo l a nd ha i r g r owth . The r e s ponses t o a c ha nge i n photope r i od a r e n o t i mmed ia te a nd gene t i c d i f f e r e nces betwe e n a n i ma l s 4 0 can a l t e r t he e xp r e s s i v i ty o f the woo l g r owth r hythm . t h e i nt e r pr e t a t i on o f l i ght r hythms a nd t h e i r e f f e c t s on t he e ndocr i ne sys t e m a r e d i s cuss ed i n S e c t i o ns 5 . 3 a nd S . 4 . The e f f e c t o f i nd i v i d ua l h o rmones o n woo l gr owth i s d i scussed l a te r . 5 . 1 . 2 Ha i r a nd woo l gr owth cyc l e s 5 . 1 . 2 . 1 S hedd i ng S e ve r a l f o rms o f ha i r g r owt h cyc l e e x i s t . Many f u r bear i ng a n i ma l s a nd ung u l a t e s s uc h a s dee r , ca t t le a nd p r im i t i ve s h e ep undergo a c omp l e t e mou l t e i t h e r once a yea r ( i n s pr i ng ) o r twi c e a yea r ( i n s pr i ng a nd a u tumn ) . Ryd e r a nd S t e phenson ( 1 9 6 8 ) have d i s cussed t h e s e mou l t i ng cyc l e s i n s ome d e ta i l . Al t hough mos t breeds o f s he e p do n o t have a de f i n i te mou l t , many s h e e p d o show a ppr e c i a b l e s hedd i ng , e i the r o f woo l o r k emp f i br e s . I n d ome s t i c b r e eds , t he pr o po r t i on o f f i br e s under go i ng r e p laceme nt i s l owe r a nd s pread ove r a l o nger t ime than i n w i ld s h e ep a nd s o n o de f i n i te mou l t i s apparen t . D i f f e r e nces i n s hedd i ng be twe e n breeds i s par t i a l ly due t o d i f fe r i ng p r opo r t i ons o f t he ma i n f i br e t ypes . S ea s ona l c hanges i n t he r a t e o f woo l g rowt h r e p r e s e n t a l e s s drama t i c man i fe s ta t i on o f a nc i e n t s hedd i ng cyc l e s ( Hu tch i ns o n a nd Wod z i cka -Toma se ws k a 1 9 6 2 , Hutch i ns o n 1 9 6 5 , 19 7 6 ; Ryd e r a nd S te phenson 1 9 6 8 ) . Ma r go l e na ( 1 9 6 0 ) r e l a t ed r educed w i nt e r woo l g r owth t o a r educt i on i n the rate o f ce l l d i v i s i on i n t he f o l l i c l e b u l b . 5 . 1 . 2 . 2 Na t ur a l adapt i on Johnson ( 1 9 8 4 ) , among o the r s , has r e v i ewed the adapt i ve na ture o f s eas o na l c oat c ha nges i n mamma l s . I n w i ld a n i ma l s , t h e mos t d rama t i c s easona l c ha nges i n p e 1 age i nvo l ve a c ha nge o f c o l our wh ich a i ds i n both t empe rature 4 1 r e g u la t i o n a nd p rotect i ve camo u f l age . Whe ther o r n o t a c o l ou r change occur s , s eas ona l mou l t i ng pr oduces c oa t s o f va ry i ng d e n s i ty a nd s tr uc t u r e wh i c h a r e ada pted t o the e nv i r o nme nt . Dome s t i ca t i on t e nd s to d i s e ngage the s e a s o na l , h o rmo na l a nd mou l t cyc l e s . I n t he e xt r eme case o f l a b o ra t o ry r ode nts t h e r e i s n o s e a s o na l mou l t a nd no s eas o na l changes i n the e nd oc r i ne sys tem a l though ha i r g r owth c an s t i l l be i n f l ue nced by hormo ne s . I n b r e eds o f s h eep wh i c h u nd e rgo a nnua l s hedd i ng o f the e n t i r e f l ee c e such as t h e Mou f l o n ( Ryde r 1 9 6 0 ) , t he W i l ts h i r e H o r n ( S l e e 1 9 6 3 , 1 9 6 5 ; Ryd e r 1 9 6 9 , 1 9 7 3 ) , the S he t l a nd ( Ryder a nd S t e phe n s o n ( 1 9 6 8 ) a nd the S oay ( Boyd e t a l . 1 9 6 4 , Ryd e r a nd S t e phe ns o n 1 9 6 8 ; Ryder 1 9 7 1 ; Ryder a nd L i nc o l n 1 9 7 6 ) , t h e mou l t p r ogre s s e s i n s uch a way as t o never l e ave t h e a n i ma l wi t h ou t p r o t ec t i ve c ove r i ng . P r ev i ous l y d ome s t i ca ted popu la t i o ns o f s h e e p wh i ch become f e ra l d i f f e r f r om the i r pa r e nt s t oc ks i n many aspects o f woo l pr oduct i on . F l e ece we i ghts , f o l l i c l e d e ns i ty and s e condary : pr i mary ( S : P ) r a t i o a nd s ta p l e l e ngth a r e r educed i n f e r a l popu la t i ons . To a l e s s e r exten t , s e l f- s hedd i ng i s a l s o o f te n r e - e s ta b l i s hed ( Rudge , 1 9 8 4 ; B i g ham a nd Coc k r em , 1 9 8 4 ) . The adapt i ve advantage o f f l e ece s hedd i ng i n spr i ng c ou ld be r e l a t ed to therma l r e gu la t i o n o r to t he advantages of n o t car r yi ng a n eve r - i ncreas i ng amount o f woo l wh i ch wou l d a b s o r b l a r ge amounts o f wa t e r , r educe f r e edom o f moveme n t a nd b e a r i sk t o s k i n hea l t h a nd b e a phys i ca l bar r i e r t o b r e ed i ng . Hutch i nson a nd Wod z i cka -Tomasews ka ( 1 9 6 1 ) have r e v i ewed t h e f u nct i on i ng of the f l e ece i n therma l r e gu l a t i on . 5 . 1 . 2 . 3 B r eed f orma t i on Ryder a nd S t e phenson ( 1 9 6 8 ) a nd Ryd e r ( 1 9 8 4 ) d i scussed t h e 4 2 e vo l u t i on a nd dome s t i ca t i o n o f s h e ep wi t h re f e r e nce to g e ne t i c var iat i on i n ha i r a nd woo l gr owth cyc l e s . Evo l u t i on i n s he e p , wh i c h has be e n e n g i ne e red by man t hr ough s e l e c t i ve b r eed i ng , has c ha nged on l y t h e pa r t o f t h e she e p ' s c oa t wh i c h i s va l uab l e t o h i m; whe r eas , the r e s t o f te n c ont i nue s w i t h s hedd i ng cyc l e s . The r e la t i ve emphas i s p l aced o n mea t , woo l a nd c l ima t i c adapta t i o n d u r i ng b r eed forma t i o n , a nd s ubsequent s e l ec t i on , has a l s o a l te r e d t h e r espons i ve n e s s o f s he e p t o c l ima t i c a nd e nv i r onme nta l s t imu l i a nd t h e p r opor t i on o f p r i ma r y a nd s e condary f o l l i c l e s i n t he s k i n . Ryde r ( 1 9 6 0 ) s t ud i e d the s e a s o na l changes i n the c oa t o f w i l d Mou f l o n s h e ep f r om whom mos t dome s t i c s he e p a r e t hought t o have be e n d e r i ve d . Al t hough t h e e n t i r e f l e e c e was s h ed i n s pr i ng o n l y 4 0 - 6 0 % o f t he s e c o ndary f i br e s s howed br us h e nd s a t t h i s t ime . T h i s i nd i ca ted t ha t the underwo o l of wi l d s h e e p a l r eady s howed a t e ndency t owa rd s a g r owt h phase l onge r than one yea r . The o u t e r k emps ( c or r e s pond i ng t o p r ima r i e s ) f o rmed b r u sh e nds i n t h e a u tumn wh i c h we r e s hed t he f o l l owi ng s pr i ng a s f o l l i c u l a r a c t i v i ty r es umed . S imi l a r pat t e r ns occur i n Br i t i s h b reeds wh i ch s hed the i r f l eece . Dome s t i ca t i on pe r s e has n ot a lways a l t e r e d t h i s a nc i e n t cyc le , a s s hedd i ng r e l i eves t he n eed t o s hear s h eep a nd f i ne u nd e r wo o l can e a s i ly be ha r ves ted by hand in ear ly s p r i ng , be f or e pr imary f i br e s a r e s hed ( Ryde r and S tephe ns o n 1 9 6 8 ) . The e xtent o f f i br e s hedd i ng i n a var i e ty o f Br i t i s h br e e d s h a s bee n r ev i ewed by Ryd e r ( 1 9 5 7 , 1 9 5 8 ) a nd Ryd e r a nd S t e phenson ( 1 9 6 8 ) . I n h i l l b r e ed s s uch a s the S c ot t i s h B lack face a nd the Herdwi ck , s hedd i ng o f b oth pr i ma r y a nd s e c ondary f i br e s r eached as h i gh as 6 0% i n l ate wi n t e r . Down breeds s uch a s t he S u f f o l k a nd S h r ops h i r e a l s o had r e l a t i ve ly h i gh ( 3 0 - 8 4 % ) p r opor t i ons o f s hed f i b r e s . L e s s s hedd i ng seems t o occur amo ngs t L ongwo o l br eeds , but e v i d e nce i s l im i t ed . I n Me r i nos , f i bre s hedd i ng i s e xt reme ly rare ( 1% ) ( Ryde r , 1 9 6 2 ) i nd i cat i ng a g r owt h cyc l e 4 3 o f a bout 8 years . 5 . 1 . 2 . 4 Breed d i f f e r ences i n s e a sona l i ty o f wo o l g r owth F r om the a bove e v i d e nce , i t wou ld appear tha t whe r e c ha r a c te r i s t i cs o t h e r t h a n woo l have be e n favoured i n br e e d f o rma t i o n t he r e i s a g r ea te r pe r s i s te nce o f s hedd i ng . B r e eds t ha t s hed t h e mos t a l s o s how t h e greate s t s e a sona l var i a t i o n i n woo l g rowt h . Nago?ka ( 1 9 7 9 ) s umma r i zed s e a s o na l var i a t i on i n woo l g r owth d i s p l ayed by a number o f b r e eds i n var i ous l o ca t i ons whe r e t he amount o f f o od , o r l i ve we i ght , had r ema i ned c o n s t a n t t h r oughout t he yea r . The un i t of c ompar i s o n was amp l i t ude , de f i ned by Hutc h i n s on a nd Wod z i cka -Tomasewska ( 1 9 6 1 ) a s ( H- L ) / ( ( H+L ) / 2 ) whe r e H and L a r e t h e h i ghest a nd l owe s t r a t e s o f woo l g rowth , r e spec t i ve ly . A l t h ough the Me r i no a nd t h e Rambou i l l e t s how mi n i ma l s hedd i ng o f f l eece woo l , l e g k emps d o go through a s hedd i ng cyc l e ( Be nnett e t a l . , 1 9 6 2a , b ) . F o r t h i s reas o n , H u tc h i ns o n ( 1 9 6 5 ) s ugges ted t h a t t h e two cyc les may b e u nde r s e pa r a t e contr o l . The e x i s t e nce o f s eas ona l pat t e r ns o f c l ean woo l g r owt h i n t h e a bs e nce o f nutr i t i ona l o r t empe rature e f fects have been d emon s t r a ted i n p r ev i ous s e c t i on s . T h i s var iat i on i s due t o c oncomi tant changes i n l e ng t h a nd d i ame te r , a l t hough m i n i mum a nd max i mum t i mes f or l e ng t h o f t e n precede t ho se o f f i br e d i ame ter ( S t o ry a nd R os s, 1 9 6 0 ) . S easona l c ha nges a l s o occur i n the produc t i on o f a s s oc i at ed s k i n s e c r e t i ons a nd i n the s u l phur ( S ) c o n t e n t o f woo l . I n so much a s S ? c o nt e n t a nd wax a nd s u i nt p r oduct i on a r e under genet i c c o n t r o l , b reed cyc l e s i n c h em ica l c ompos i t i o n o f t he g r easy f l e e c e may r e f l e c t d i f fe r e n t r e s ponses t o seasona l e n v i r o nme nt s . 5 . 1 . 2 . 5 As soc iated secr e t i ons 4 4 B oth pr ima r y a nd s e c o ndary f o l l i c l e s have a s s o c i a ted s e ba ce ous g l a nd s t ha t p r oduce woo l wax o r g reas e ; howeve r , s ud i f e r ous g l a nd s , wh i c h pr oduce s u i n t , a r e on ly a s s oc i a ted w i t h pr i ma r y f o l l i c l e s . Da l y a nd Ca r t e r ( 1 9 5 5 ) obs e r ved i n f o u r b reed s , t ha t wa x a nd s u i nt product i on i nc r ea s ed wi t h i ntak e . Fur t h e rmo r e , wax output d ecreased a s t emperature r o s e a nd s u i nt o ut put i nc r eased as the f l e e c e g r ew . S t o ry a nd R o s s ( 1 9 6 0 ) f ound t h a t wax a n d s u i nt c ontent o f mon t h ly c l i pped samp l e s f r om gra z i ng Romneys f o l l owed a s im i l a r , a l t hough l e s s mar k ed , patt e r n t o woo l g r owt h . Th i s d i f f e r e nc e i n amp l i t ude reduces the c l ean y i e ld o f w i n t e r g r own woo l r e la t i ve t o t hat grown i n s umme r . The s e t r e nds may b e d i f f i c u l t t o d e t ec t i n f i e ld s t ud i e s und e r h i g h r a i n f a l l c o nd i t i o ns . Hutch i ns on ( 1 9 6 2 ) compar ed wax a nd s u i nt p r od uc t i on b e twe e n g ra z i ng a nd c o n s tant d i e t pen- f e d Mer i nos . I n b o t h gr oups t he p r od uc t i on o f wax a nd s u i nt f o l l owed t ha t o f woo l g r owt h , a l t hough s u i n t p r od uc t i on d i d s o t o a l e s s e r e x t e nt t ha n wax . The p r oduct i on o f s u i nt was pos s i b l y a f f e c ted mor e by tempe ra tu r e than wax produc t i o n . 5 . 1 . 2 . 6 S u l ph u r c o n t e n t o f woo l Ear l y wor k o n the s u l phur c ontent o f woo l has be e n r e v i e we d b y Ross ( 1 9 6 1c ) a nd Re i s ( 1 9 6 5 ) . As e a r l y a s 1 9 2 6 , the s u l phur c on te n t o f va r i ous samp l e s of c l e a n , dry woo l was f o und t o var y b e twe e n 3 - 4 . 1% ( Ba r r i tt a nd K i ng 1 9 2 6 , 1 9 2 9 ) . Changes i n s u l phur c o n t e n t a l ong t he s ta p l e we r e r e lated t o t h e a va i l a b i l i t y a nd qua l i ty o f pas t u r e a nd mi n i ma l changes we r e d i sp laye d by s heep o n a c ons tant d i e t ( Bonsma , 1 9 3 1 ) . O t he r wor k e r s ( Ma r s t o n , 1 9 2 8 ; F l e t ch e r e t a l . , 1 9 6 3 ) f ound l i t t l e o r n o s eas ona l c hange i n s u l phur c onte n t o f woo l . Copper de f i c i e ncy was a l s o r e lated t o a r educt i o n i n t he s u l phur c onte n t . Lat e r , Ross ( 1 9 6 f ou nd a seas ona l r hythm i n woo l s u l ph u r 4 5 c o n t e n t i n f o ur -mo n t h l y samp l e s f r om gra z i ng Romne ys that i nve r s e l y f o l l owed the s eas ona l woo l pr oduct i on . I n a n o t h e r s t udy, ( Ro s s , 1 9 6 4 ) t h e s u l phur content was f r e qu e n t l y , but n o t i nvar i a b l y , i nve r s e ly r e l a t e d t o woo l g r owt h . Ross ( 1 9 6 4 ) c o nc l ud e d that pronounced i nd i v i d ua l d i f f e r e nces i n s u l ph u r c on t ent e x i s ted a nd t ha t t h e a va i l a b i l i ty o f s u l phur was p r o bab ly n o t a fac t o r l i m i t i ng p r od uc t i on . R e i s a nd S ch i nck e l ( 1 9 6 ?,1 9 6 4 ) s howed t ha t woo l g r owth and t h e s u l phur c ontent o f woo l we r e i ncreased wi t h add i t i o na l a boma s a l supp l i e s o f s u l phur - conta i n i ng ami no a c i ds . Re i s ( 1 9 6 5 ) c o n f i rmed t h i s r e la t i ons h i p . Re i s and Wi l l i ams ( 1 9 6 5 ) , a l s o us i ng Me r i nos , s howed that t he pos i t i ve r e l a t i ons h i p betwe e n woo l g r owt h a nd woo l s u l phur c o n t e n t i n g ra z i ng s he e p was r e l a t e d t o n ut r i t i ona l , not c l i ma t i c , cyc l e s . They a l s o s ugge s te d t ha t the s u l phur c o n t e n t o f woo l may have a n i nt r i ns i c m i n i mum, such t ha t d i e ta r y d e f i c i e nc i e s c o u l d r ed uce woo l g r owth f u r t he r , w i t h o u t r educ i ng s u l phur c o n t e n t b eyo nd t h i s m i n i mum . S umn e r ( 1 9 7 9 ) f ound a pos i t i ve a s s o c i a t i o n be twe e n woo l growt h , f i b r e d i amet e r , and s u l phur c o n t en t i n a var i e ty o f b r e e d s ma i nt a i ne d i nd o o r s i n l o ngterm s t ud i e s . O the r s have c ompar e d t h e s e a s ona l cyc l e o f s u l phur c o n t en t i n va r i ous b r e ed s s ub j e c t ed t o a l te red nutr i t i o na l r e g i me s ( Re i s a nd W i l l i ams , 1 9 6 5 ; P i pe r a nd Do l l i ng7 1 9 6 6 ; D oney a nd Evans , 1 9 6 8 , 19 7 0 ) . T he s e s t ud i e s wi l l be r e v i ewe d i n t he f o l l ow i ng s ect i on . 5 . 1 . 3 Ge ne t i c d i f f e r e nc e s i n r e s ponse t o s easona l a nd nutr i t i ona l cyc l e s . 5 . 1 . 3 . 1 Photoper i od i c s e ns i t i v i ty P h o t ope r i od i c s e ns i t i v i ty p lays a subs tant ia l r o l e i n p r oduc i ng woo l gr owth pat t e r ns characte r i s t i c o f e a c h b r e ed . T h e reduced d e pe nd e nc e o f t h e Me r i no cyc l e h a s be e n 4 6 d emons trated e a r l i e r and i s pe r haps a p r od uct o f i ts med i te r ranean o r i g i ns a nd adapta t i on ( na tura l o r d i r e c t e d ) t o s e a s ona l m igra t i on and a u tumn lamb i ng ( Ryde r a nd S tephenson 1 9 6 8 ) . Al though o t h e r e qua t o r i a l b r e eds s ha r e t h e Me r i n o ' s a b i l i ty t o b reed yea r - r ound , l i t t l e i s k n own o f t h e woo l g r owt h cyc l e i n t h e s e b reeds . The n o r t h e r n e xce p t i o n t o s t r ong ly p hotope r i od i c r ep roduct i on i s t h e Dor s e t H or n . N o pub l i s hed e s t i ma t e s o f i ts s ea s o na l woo l g r owt h pa t t e r n we r e f ound . The d eve l o pment o f an e x t ended br e ed i ng s eas o n , r e nowned as e a r l y as t he 1 7 0 0 ' s ( Ryde r a nd S te phenson 1 9 6 8 ) i s cur i ous g i ve n i ts s u ppose? c l os e a ncest ry to the S oay . Ev i d e nce f r om n o r t h e r n and s o uthe rn s tra i ns o f wh i t e - f oo t ed m i c e ( Connect i cu t a nd Ge or g i a ) s h owed that me l a t on i n , a p i ne a l i nd o l -ami n e i nvo lved i n photope r i od i c r e gu lat i on , had l i t t l e e f f e c t o n mou l t i ng o r r e pr oduc t i ve pat t e r ns i n t h e s outhe r n m i c e , but was capab l e o f i nd uc i ng mou l t t o w i nt e r pe lage a nd l os s o f r e pr oduct i v e c ompet e nce i n t h e nor t h e r n m i c e ( He a t h and Lynch 1 9 8 2 ) . I t i s pos s i b l e tha t s i mi l a r i nt r a - s pe c i f i c d i f f e r e nces i n t h e s ens i t i v i ty o f the e nd oc r i ne s ys t em t o me l a t on i n occur w i t h i n o r b e twe e n b r e eds o f s h e e p , but e xpe r i me nt s t o t h i s e nd have n o t be e n r e po r t ed . Ge ne t i c d i f f e r e nc e s i n the s easona l r e s ponse o f woo l g r owt h t o e nv i r onme nta l e f f ects s e em to be r e l a t e d t o t h e s e d i f f e r e nc e s i n pho t ope r i od i c s e ns i t i v i ty , a l t hough t he p r ec i se mecha n i s ms a r e unc l ea r . 5 . 1 . 3 . 2 B r e e d by s eason i n te ract i ons i n r e sponse t o n ut r i t i ona l e f f e c t s Woo l gr owt h The i nt e r pr e ta t i on o f annua l r hythms o f woo l gr owt h i n d i f f e r e n t b r eeds a nd d i f f e r e nt e nv i r onme nts i s mad e d i f f i cu l t b y t h e i nab i l i ty t o s e parate poss i b l e s easona l i nt e ract i ons be t we e n b reeds a nd nutr i t i o na l a nd s e a sona l e f f e c ts . B r e ed compa r i s ons o n s eque n t i a l nutr i t i ona l r e g i me s can i nc l ud e i nt e r ac t i o ns w i t h s eason . 4 7 Whe n Da ly a nd Ca r t e r ( 1 9 5 5 } i mpos ed p rogr e s s i ve ly r e s t r i c t i ve i nt a k e s o n Mer i n o , P o l wa r t h , Cor r i eda l e and L i nc o ln e we s they o bs e r ve d ( i n d e s c e nd i ng o rde r o f magn i tude ) a r educt i on i n c l ea n woo l gr owt h . I n t h i s e xpe r ime n t , ge ne r ous f e ed i ng was p r ov i de d i n t h e Aus tra l i a n w i n t e r ( Ju l y ) a nd f u l l r e s t r i ct i on was c omp l e t e b y s ummer ( De c embe r ) . F r om o t h e r s t ud i e s , i t i s l i k e ly that t he L i nc o l n s heep we r e be i ng r e l a t i ve ly mor e h e ld back ( i n J u l y ) by non-nut r i t i o na l fac t o r s a nd t hus , we r e l e s s a f f e cted ove r a l l , b y t he r ed uct i on i n nutr i t i on f r om w i n t e r t o s umme r . D oney ( 1 9 6 6 ) add r e s s ed t h i s t o p i c d i r ec t l y by o f f e r i ng C he v i ots a nd 3 / 4 Me r i no s e i t h e r l e ve l , na tura l o r r e ve r s ed a nnua l i ntake cyc l e s . I n Me r i nos , t h e be twe e n s he e p va r i a t i o n i n i nta k e was r e f l e c ted by d i f f e r e nces i n woo l g r owth i n a l l pe r i od s , but i n Che v i o t s h e e p i nta k e a nd woo l g r owt h we r e r e l ated i n s umme r but n o t i n w i n te r . The e f f ec t of add i t i ona l nutr i t i o n i n w i n t e r o n woo l gr owt h has b e en s hown t o b e m i n i ma l i n S c o t t i s h B lac k face s he e p ( Doney 1 9 6 4 ) a nd i n t h e S oay ( Doney , unpub l i s hed ) . H i s r e s u l ts s ugges t ed t ha t the gene t i c d i f f e r e nc e s i n me tabo l i c r e s ponses t o ' ' unspe c i f i ed s easona l f act or s " m ight be r e moved by i nt e ns i ve s e l e c t i on for i ncreased woo l gr owt h . I n a l a t e r s t udy , Doney a nd Evans ( 1 9 7 0 ) f e d R omney a nd B lac k face e we s to ach i e ve d i f f e r e n t pa t t e r ns o f l i ve -we i ght change f r om mat i ng t o pa r tur i t i on and a c h i eved a woo l g r owth r e s ponse i n Romneys , but not i n the B lack face s he e p . A l t h ough b reed r e s ponses t o n ut r i t i on have be e n s hown t o va r y i n t h e wi nt e r , Doney a nd Ead i e ( 1 9 6 7 ) and B i gham e t a l . ( 1 9 7 8a , b ) have s hown that woo l gr owt h over the summer per i od va r i e d mos t , both w i t h i n and betwe e n b r eeds on pas t u r e . A l s o , summer nutr i t i on had a g r ea t e r i n f l ue nce on t ota l 4 8 f l e e c e p roduc t i on than pe r f o rma nce i n w i n ter . B i gham e t a l . ( 1 9 7 8 ) c o ncur r ed w i t h S umne r ( 1 9 7 7 , 1 9 7 9 ) that b r e ed c ompa r i s ons i n s ho r t t e rm s t ud i e s may d e pe nd grea t l y on t h e t i me o f t he yea r dur i ng wh i c h t h e s t ud i e s a r e cond ucted . I n -de pt h c ompar i s ons o f s e a s ona l woo l g r owt h i n s e l e c t i on l i ne s have n o t be e n r e po r t ed . Us i ng s h e e p w i t h p r e v i ous l y h i g h o r l ow f l e ec e we i ght ( 6 s h e e p e ach ) o n two pas ture t yp es , Re i s a nd Wi l l i ams ( 1 9 6 5 ) s h owed g r eate r s eas ona l var i a t i on i n c l ea n woo l g r owth i n phenotyp i ca l ly h i gh t h a n l ow p r oduc i ng s h e e p , t h e a bs o l ut e d i f f e r e nce be i ng g r ea t e r i n p e r i od s o f h i gh r a the r t han l ow p roduc t i on . Hawk e r e t a l . ( 1 9 8 5 ) , o n t h e bas i s o f f our samp l e s p e r yea r , c o u l d n o t d e tect a d i f f e r e nc e i n t h e annua l pa t te r n o f woo l g r o wt h b e twe e n c ont r o l a nd h i gh hogget gr easy f l e e ce we i gh t s e l e c t i on l i ne s , a s t h e e nt i r e c u rve s e emed t o b e l i f ted i n t h e s e l e c t i on l i ne . Hawk e r and Cr o s b i e ( 1 9 8 5 ) , s e pa r a t e d R omney a nd P e r e nda l e ewe s wh i ch had e i th e r h i gh ( W+ ) o r l ow ( W- ) w i n t e r woo l gr owt h , and f ed t h em a t e i ther h i gh o r l ow l eve l s i n t he f o l l owi ng s umme r a nd w i nte r . The r e wer e ma r k e d woo l gr owth d i f f e r e nc e s i n w i n t e r be twe e n W+ a nd W? e we s . Wo o l gr owt h d i f f e r e nc e s d i d n o t e x i s t i n t h e s umme r . The W+ e we s a l s o r e s ponde d t o h i gh l eve l s o f w i n t e r f e e d i ng wh i le W- e we s d i d n o t . Thus , phe notyp i c s e pa ra t i on , o n t h e bas i s o f w i n t e r woo l g r owth , was s uccess f u l i n i d e n t i fy i ng s he e p w i t h d i f f e r e nt s eas ona l r e s pons e s t o n ut r i t i on a nd r epeatab l e d i f f e r e nc e s i n w i n te r woo l p r oduc t i on . S u l ph u r c on t ent The f i r s t e v i d e nce t ha t t he s u l phur content o f woo l may b e u nd e r ge ne t i c cont r o l was f o und by G i l l e s p i e ( 1 9 6 5 ) i n t h e e xam i na t i on o f mutant and n o rma l woo l f i br e s produced by f l e e ce mosa i c i sm, a s oma t i c muta t i on t hought t o occur i n e ar ly embryon i c deve l opment ( Lang 1 9 5 2 , F raser and S h o r t 4 9 1 9 5 8 ) . Mutant ( l o ng ) f i br e s had h i gh e r pe r c en tages o f s u l phur ove ra l l , c haract e r i ze d by a l owe r pr o por t i on o f h i gh s u l phur p r o t e i ns a nd a h i ghe r p ropo r t i on o f med i um s u l phur p r ot e i ns t ha n t h e n or ma l s h o r t e r woo l f i br e s . G i l l e s p i e ( 1 9 6 5 ) a l s o f o und t ha t l u s t r e mutant Me r i nos ( S hor t 1 9 5 8 ) i nc o r porated mor e h i gh s u l phur pr o t e i ns i nt o woo l f i bres t han norma l s i bs o n s im i l a r d i e ts . T h i s d i f f e rence was t hought t o b e due t o a l a r g e r p r opor t i on o f para c o r t ex i n t h e s e l us t r o us f i bre s , t h e para c o r t e x be i ng t h e s e gment i n n o rma l Me r i n o woo l t h o ught t o be r i chest i n h i gh s u l phur p r o t e i ns . Re i s a nd W i l l i a ms ( 1 9 6 5 ) , c ompar i ng t he i r r e s u l t s o n the s easona l i ty o f woo l s u l phur content w i t h those o f Ross ( 1 9 6 1 , 1 9 6 4 ) , c o nc l uded that d i f f e r e nc e s b e twe e n the r e s u l t s may b e d ue t o t he mor e s e ns i t i ve s e a s ona l i ty o f woo l gr owt h i n R omneys c ompa r e d t o Me r i nos i e . e f f e ct s o the r t h a n l ow d i e ta ry s u l phur c ont ent d e pressed woo l g r owt h i n Romney s h ee p . Re i s and W i l l i ams ( 1 9 6 5 ) a l s o f ound t ha t h i gh pr oduc i ng s he e p had h i ghe r f e e d e f f i c i e nc i e s a nd l owe r s u l phur c ontent i n t h e woo l . The h i gh p r oducer s had gr e a t e r s easona l var i a t i on i n s u l phur conte n t , poss i b l y d ue to a h i ghe r l e ve l o f s u l phur s ubstrates be i ng ava i l a b l e t o l ow p r od uce rs . Dur i ng t ime s o f nutr i t i ona l s t r e s s , t h e s u l phur c on t ent f r om h i g h p r oduce r s f e l l t h e mos t , as h i gh produc e r s ma i nta i ned g r e a t e r woo l g r owt h und e r t h e s e cond i t i ons . P i pe r and D o l l i ng ( 1 9 6 6 ) c ompared h i g h and l ow f l e ece we i ght s e l e c t i on l i n es g razed t oge the r on l ow q ua l i ty pas tures . The c o r r e l a t i on be twe e n s u l phur c ontent and woo l g r owt h was ( - . 6 9 and + . 2 8 ) w i t h i n l ow a nd h i gh s e l e c t i on l i ne s , r e s pect i ve l y . The l ow l i ne a l s o had l a rg e r va r i a t i on i n s u l phur cont e n t a nd a s s u l phur was l i k e l y not l i m i t i ng t he i r woo l gr owth t h ey d i s p layed t he norma l woo l gr owth? s u l phur c ontent r e l a t i ons h i p . I n c on t ras t , the h i gh f l e e ce we i gh t l i ne was l i k e ly n ear i ts mi n i mum l e ve l o f woo l s u l phur conte n t . These r e s u l ts s ugge s ted d i f f e r e nces i n the 5 0 e f f i c i e ncy o f ut i l i za t i on o f s u l phur a t the f o l l i c u l a r l e ve l . G i l l e sp i e ( 1 9 6 5 ) i n a r ev i ew o f much o f h i s own wo r k , s howed that h i gh pr oducers had l owe r ove ra l l woo l s u l phur content c haracte r i zed by l owe r pr opor t i ons o f h i gh s u l phur p rote i ns i n t h e f i b r e matr i x . D oney a nd Evans ( 1 9 6 8 ; 1 9 7 0 ) c ompared Me r i n o w i t h Chev i o t s he e p a nd S cott i s h B la c k face w i t h Romney s he e p f o r t h e i r woo l gr owt h a nd woo l s u l phur c ontent und e r va r i ous nutr i t i ona l p lanes ove r w i n t e r . S i gn i f i cant b reed d i f f e r e nces i n t h e woo l g r owt h -s u l phur content r e l a t i on s h i p we r e r e po r t ed wh i ch s uppo r t ed the conc l us i ons o f R e i s a nd W i l l i ams ( 1 9 6 5 ) . I n a l l r e po r t ed s tud i e s , l a rge w i t h i n gr oup d i f f e r e nces i n s u l phur conte nt e x i s ted a nd we r e , i n many cas e s , gr e a t e r t ha n t h e d i f f e r e nces betwe e n gr oups . 5 . 1 . 4 Hormona l e f f e c t s R e v i e ws o f t he h o rmona l r e gu l a t i on o f woo l gr owth have be e n p r e pa r e d by Downes and Wa l lace ( 1 9 6 5 ) , Fe rgus o n , Wa l la c e and L i nd le r ( 1 9 6 5 ) , Ryd e r a nd S t e phenson ( 1 9 6 8 ) a nd Wa l l ace ( 1 9 7 9 ) . Eb l i ng a nd Ha l e ( 1 9 8 3 ) have a l s o r e v i ewe d t h i s t op i c but w i t h empha s i s o n s pec i es d i f f e r e nces a nd h uman ha i r growt h . F e rguson ( 1 9 5 8 ) d i s t i ng u i s hed be t we e n t h r e e types o f h o rmone a c t i on . F i rs t , h ormone s may have a pe rmi s s ive r o l e , whe r e s e c r e t i ons a r e n e c e s sa ry f or woo l gr owt h t o ta k e p la c e b u t va r i a t i on i n s e c r e t i o n i s w i thout e f f ect . S econd ly , the r e i s a r e gu lator y r o l e whe r e va r i a t i on i n s ecr e t i on r a t e c ont r o l s t he l e ve l o f wo o l produc t i on and proba b l y s hedd i ng . Th i r d l y , s ome h o rmones a r e capab l e o f e l i c i t i ng a pharmac o l og i ca l e f f e c t a nd can pr omote woo l gr owth i f admi n i s t e r ed a r t i f i c i a l ly i n amounts gr eater than t h o s e i n n orma l s ecre t i on . I n e a r l y s t ud i e s the e f fects o f g l a nd r e mova l and subs e quent r e p l aceme n t therapy y i e l ded muc h k nowl edge but was hampe r e d b y h e t e r oge ne ous ho rmone pre pa ra t i ons a nd t he d i f f i c u l ty o f mea s u r i ng s pe c i f i c h or mone c onc en t ra t i ons i n p l a sma . 5 . 1 . 4 . 1 P i t u i ta ry a nd assoc i a te d ta rge t g la nd hormo ne s 5 1 The p i t u i ta ry i s t he centra l g l a nd o f t h e e nd ocr i ne sys t em . S ome o f t h e p i t u i ta r y hormo ne s a c t by s t i mu la t i ng o t h e r e ndocr i ne g l a nd s . For t h i s r e a s o n , t h e t a rge t t i s s u e s a nd t he i r s e c r e t i ons wi l l b e d i sc us s ed a l ong wi th the i r c ont r o l l i ng p i tu i ta ry hormones . F e rguson ( 1 9 5 1 ) d e s c r i bed a t echn i que f o r hypophysec t omy i n t h e s h e e p and f o und t hat woo l g r owt h was r educed t o ve r y l ow l e ve l s f o l l ow i ng t h i s p rocedur e . I n mos t cas e s woo l gr owth c ea s ed comp l e t e ly a f t e r 4 - 2 6 we e k s ( Fe rgus on e t a l . 1 9 6 5 ; G i ra r d 1 9 6 9 ) i nd i ca t i ng that a t l e a s t one o f t he p i t u i t a ry h o rmones must be pr e s e nt f o r woo l gr owth t o occur . Thyr o i d s t i mu l a t i ng hormone ( TS H ) a nd t hyr o i d hormones The t hyr o i d g la nd r eacts to t h e p i t u i ta r y hormone T SH by r e l eas i ng Thyr ox i ne ( T 4 ) and Tr i od o t hyr on i ne ( T3 ) . T 3 i s mor e b i o l og i ca l ly a c t i ve than T 4 a nd T 4 i s a l te r ed t o T 3 by body t i ss u e s ( F i s h e r e t a l . 1 9 7 2 ) . I n hypophysectomi zed s he e p , d a i ly s ubcutaneous admi n i s t ra t i on o f T 4 can r e s t o r e woo l gr owt h t o pr e - operat i ve l e ve l s , b u t cannot r a i s e i t above t h i s ( Fe r guson e t a l . 1 9 6 5 ) . The woo l gr owt h o f t hyr o x i n e -ma i nta i ned hypophys e c t om i zed s h e e p s t i l l var i es b e twe e n i nd i v i d ua l s , be i ng p ropor t i ona l t o pre -ope r a t i ve l e ve l s ; t h e r e f o r e , t h i s va r i at i on mus t be due t o d i f f e r e nc e s i n t h e s t r ucture or d e ns i ty o f f o l l i c l e s i n t he s k i n or o t h e r sys tem i c fac t or s . Thyr o idectomy r educes woo l gr owt h t o a ppr o x i mate ly 6 0 % o f p r e - operat i ve l eve l s , due e nt i r e l y t o a r e d uct i on i n f i br e l e ngth gr owth r a t e ( S i mpson , 1 9 2 4 ; Ma r s to n and Pi e r c e , 5 2 1 9 3 2 ; Fe rgus o n , 1 9 5 1 ; The r i e z a nd Rouge o t , 1 9 6 2 ) . I n c o n t r a s t t o hypophys e c t omi z ed s h e e p , woo l gr owth i n t hyr o i de ct omi zed s he e p ca n b e ra i s ed a bove pre - o pe ra t ive r a t e s by i ncreas i ng t h e d o s e o f T 4 ( Fe r gus o n e t a l . 1 9 6 5 ) , s ugge s t i ng that s ome o t h e r p i t u i ta ry h o rmon e i s n ecessa r y f or t hyr o i d h o rmon e s t o e xp r e s s t h e i r f u l l phys i o l og i ca l a c t i v i t y . Downes a nd Wa l la c e ( 1 9 6 5 ) d emo ns t rated a d i r e c t e f f e c t o f t hyr ox i ne o n woo l gr owt h , s ugge s t i ng t ha t t hyr o x i ne can i nc r ea s e t h e o utput o f wo o l f o l l i c l e s a ppa r t f r om sys temi c e f f e c t s s uc h a s changes i n a ppe t i t e o r gene r a l me tabo l i s m . N ot a l l a t tempts t o mod i fy t hyr ox i ne l e ve ls have r e s u l t ed i n changes i n the a c t i v i ty o f the wo o l f o l l i c l e ( Ryde r 1 9 7 3 , 1 9 7 9 ) . C o o p a nd C l a r k ( 1 9 5 8 ) s howed s easo na l e f f e ct s o n t hyr o x i ne r e s po n s e w i t h e f f e c t s be i ng s hown i n m i ds umme r t o a u tumn , b ut n o t i n m idwi n t e r o r e a r l y summe r . Har t ( 1 9 6 1 ) f o und d i f f e r e nc e s i n t he t hyr o i d g la nds o f va r i ous l i g h t t r eatme nt gr o ups , but a s the g l a nd we i ghts a nd woo l gr owt h we r e n o t a l ways pos i t i ve ly r e l a t ed h e c o nc l ud e d t ha t the r e mus t b e a l a t e ncy o f r e sp ons e . Wa l la c e ( 1 9 7 9 ) c o nc l uded t h a t thyr o i d h o rmo ne s we r e n o t i nvo lved i n the s e a s o na l i ty o f woo l g r owt h wh i l e Ryd e r ( 1 9 7 9 ) a nd L i nc o l n e t a l . ( 1 9 8 0 ) f ound a s t r o ng pos i t i ve c o r r e la t i o n be twe e n woo l gr owth a nd c i r c u l a t i ng l e ve l s o f thyr ox i ne . R o uge o t e t a l . ( 1 9 8 4 ) q u o t e a s s oc i a t i o n s be twe e n thyr ox i ne a nd mou l t i ng pe r i od s i n t h e m i n k a nd i n t h e h a rbour s ea l . K ha t e e b a nd J o h ns o n ( 1 9 7 1 ) c o nc l uded f r om wo r k w i t h vo l e s t ha t the s e a s o na l r eg u l a t i on o f ha i r a c t i v i ty i s due t o t h e i nt e r ac t i on o f t hyr o x i ne w i t h o t h e r h ormon e s such a s adr e na l a nd g o nada l s t e r o i d s . T h e s e r e s u l t s s ugge s t t hat t hyr ox i ne e xh i b i ts p e rm i s s i ve , r e gu latory a nd pha r maco l o g i ca l e f f e c ts o n wo o l g r o wt h . P h o t o pe r i od i c c o nt r o l o f t hyr o i d h ormones wi l l be d i scussed i n s ubs eque n t s e c t i o ns . 5 3 Ad re noco r t i co t r o ph i c h o rmon e ( ACTH ) a nd C o r t i s o l ACTH e xe r t s i ts phys i o l o g i ca l act i on b y i ncr eas i ng t h e s e c r e t i o n o f s te r i ods f r om t h e a d r e na l g land . One c la s s o f t h e s e s te r o i d s , the g l u c oc o r t i c o i d s , may s t i mu l a t e wo o l g r owt h whe n pr e s e n t i n ve ry sma l l amo un t s ( Downes a nd Wa l lace 1 9 6 5 ; Chapman a nd Bass e t t 1 9 7 0 ) and whe n g i ve n i n t he who l e a n i ma l ( ra t he r t ha n l oca l ly t o the d e rmi s ) may d e pe nd o n t h e a b i l i ty t o i nc r e a s e f e ed i nta k e . At h i gh e r l e ve ls , c o r t i c o s t e r o i d s i nh i b i t f o l l i cu la r act i v i ty r e s u l t i ng i n d e c r eased f i br e d iame t e r and l e ngt h gr owth r a t e a nd i nc r eased s hedd i ng ( L i nd l e r a nd Fergus o n 1 9 5 6 ; F e rgus o n e t a l . 1 9 6 5 ; P ana r e t t o e t a l . 1 9 7 5 ) . I ncreased ad r e no -c o r t i ca l act i v i ty i n t imes o f phys i ca l o r psych o l og i ca l s t r e s s can be s ome t i me s r e s pons i b l e f or " br ea k " o r " te nd e r nes s " i n the f l e e c e . Pa nare t t o a nd Wa l lace ( 1 9 7 8a , b ) i nve s t i gat ed t h e u s e o f powe r f u l syn th e t i c a na l ogues o f c o r t i c os t e r o i d s f or c hem i ca l de f l e e c i ng but t he i r r e s u l ts we r e n o t s u f f i c i e nt ly p r ed i ctab l e f or c omme r c i a l u s e . E b l i ng a nd Ha l e ( 1 9 8 3 ) c ommen t ed t h a t t h e a b i l i ty o f c or t i c os t e r o i d s t o a f f e c t f o l l i c u la r a c tivity we?s s urpr i s i ng i n l i ght o f War d a nd Kasma r i k ' s ( 1 9 7 9 ) r e s u l t t ha t woo l r o o t s we r e una b l e t o me tabo l i ze c or t i s o l a s t h ey lack l l B? hyd r oxys te r o id d e hyd r ogenase wh i ch i s p r e s ent i n o ther pa r t s o f t h e s k i n . The 1 7B f orm i s , h oweve r , u b i q u i t o us . Wa l lace ( 1 9 7 9 ) quoted h i s own unpub l i s he d wor k s howi ng t ha t c o r t i s o l d e p r e s s e s t he upta k e o f cys t e i ne i n t o woo l f i b r e s . L i nd l e r a nd F e r gus on ( 1 9 5 6 ) s ugges t e d that adr e nocor t i ca l a c t i v i ty may be r e spons i b l e f or t he d e c r eased woo l g rowt h i n w i n t e r b u t ad r e na l ectom ised e we s o n c onstant r ep laceme nt the rapy s t i l l e xh i b i ted s ome s eas o na l i ty o f woo l growth . R i v i e r e e t a l . ( 1 9 7 7 ) a t t r i buted t h e mou l t i ng per i od i n ha r bour s e a l s t o f l uc tua t i ons i n t h e ba lance o f c or t i s o l a nd t hyr ox i ne , w i t h t hyr ox i ne i nc r e a s i ng f r om June t o J u l y ( the mou l t i ng pe r i od ) a nd c o r t i s o l d ecreas i ng ove r t h i s p e r i od . F e rgus o n e t a l . ( 1 9 6 5 ) a l s o s howed that c or t i s o l i n f l ue nced the wo o l g r owt h r e s po nse t o thyr o x i ne whe r eas c or t i s o l a t h i gh e r c i r c u la t i ng l eve l s p r eve nted a ny r e s ponse t o thyr o x i ne . G r owth Hormone 5 4 G r owt h h ormone i s n o t t hought t o a c t t h r ough a s e c ondary o rgan , but i t d o e s s t i mu la t e t he s e c r e t i on o f o n e o r mor e p o l ypept i d e s , k n own a s s oma t omed i ns , pr i ma r i ly f r om t h e l i ve r b u t a l s o f r om mos t o t h e r t i s s ue s e xami ned . Gr o wth h ormone cannot i n i t i a t e wo o l g r owt h i n hyp ophys e c tom i s ed s he e p ma i nta i ne d o n T 4 ( Fe rgus o n e t a l . 1 9 6 5 ) . I n n o rma l s h e e p gr owt h h o rmo n e was a b l e t o s t i mu l a t e woo l gr owt h a f t e r t he gr owth h ormone i n j e c t i ons ceased ( Fe rgus o n , 1 9 5 1 ; 1 9 5 4 ; F e rguson e t a l . , 1 9 6 5 ; Whe a t l e y e t a l . , 1 9 6 6 ; R e k l e ws k a , 1 9 7 4 ; Wynn e t a l . , 1 9 7 9 ) . The s e changes occured pr i ma r i ly t h r ough a n i nc r e a s e i n f i br e d i amet e r . C ontrary t o t h e r e s u l ts o f Labba n ( 1 9 5 7 ) , g r owt h ho rmo ne d i d n o t change t h e n umbe r o f f o l l i c l e s i n a ny o f t h e a bove s t ud i e s . Many s t ud i es s howed a d e p r e s s i on i n woo l gr owt h dur i ng t h e pe r i od o f h o rmone i n j e c t i o n s . Wynn e t a l . , ( 1 9 7 9 ) a tt r i buted t h i s t o a n i nc r ease i n t i s s ue p r o te i n r e t ent i on dur i ng t r e atme nt f o l l owed by pr o t e i n mob i l i za t i on a f te r gr owt h h o rmo n e i n j e c t i ons ceased . I ntraderma l i n j e c t i o n s o f g r owth h o rmone ( Downes a nd Wa l lace 1 9 6 5 ) d i d n o t a l t e r wo o l g r owt h rate , t h e r e f o r e , g r o wt h h ormone i s un l i k e l y t o have a d i r ec t e f f e c t o n t h e f o l l i c l e . I t a l s o s e e ms un l i k e ly tha t g r owt h h ormon e i s i nvo lved i n t h e s e a s o na l i ty o f woo l gr owth ( Wa l lace 1 9 7 9 ) . P r o lac t i n Wa l lace ( 1 9 7 9 ) c o nc l ud e d t ha t p r o lact i n was unl i k e l y t o be i nvo lved i n wo o l g r owt h . The i n j e ct i on o f pr o la c t i n i n t o 5 5 n o rma l o r hypophys e ct omi s e d s h e e p ( Fe rgus on e t a l . 1 9 6 5 ) d i d n o t a f f e c t woo l gr o wt h . Ve r y l ow a nd very h i gh i n trade rma l i n j e c t i o ns o f pr o lac t i n i nc r eased l e ngth g r owt h r a t e o f woo l f i br e s , wh i l e i n t e rmed i a t e l eve ls r e s u l te d i n a d e c r ea s e ( Downes a nd Wa l l a c e , 1 9 6 5 ) . P r o lact i n cyc l e s i n t h e f i e ld a r e pos i t i ve ly a s s oc i at e d w i t h the a nnua l t empe ratur e cyc l e , a nd wi t h t he wo o l g r owth cyc l e but S m i t h e t a l . ( 1 9 7 7 ) we r e mor e w i l l i ng t o accept the f o r me r , r a t h e r t ha n l a t t e r , a s t he d i r e c t a s s oc i a t i on . R o uge o t e t a l . ( 1 9 8 4 ) c o ns i d e r ed pr o lact i n t o be i nvo lved i n t h e woo l gr o wth cyc le . I n m i n k a nd i n s he ep , s pr i ng mou l t c o i nc i ded w i t h a s e a s o na l i nc r ea s e i n p lasma p r o l a c t i n ( Ma r t i ne t e t a l . , 1 9 8 2 ; Rava u l t , 1 9 7 6 ) a nd a utumn mou l t i n m i n k i s a ssoc i at e d w i t h l ow o r d e c r ea s i ng leve l s o f p r o l ac t i n . I n e x p e r i me n ta l c o nd i t i ons , m i n k k e pt u nd e r 1 6L : 8 D f r om s ummer s o l s t i c e unde r we n t a mou l t but t o a n o t h e r s umme r c oa t . Und e r s im i l a r c o nd i t i o ns , b ut w i t h da i ly i n j ec t i ons o f e r g oc r i pt i n ( a pr o lact i n i n h i b i t o r ) a n or ma l autumn mou l t occur r e d . Und e r 8 L : l 6 D pr o la c t i n was u na b l e t o e l i c i t a spr i ng , r a t h e r t ha n a utumn , mou l t . G o nado t r oph i c h o rmones The g o nadotr oph i ns s t i mu l a t e t h e ova r i e s and t e s t e s t o s e c r e t e phys i o l og i ca l ly a c t i ve s te r o i d s . Ve ry l i t t l e wo r k has be e n d o ne o n t h e e f f e c t s o f s e x h o rmo nes o n wo o l g r o wt h i n s he e p . Gonada l a nd woo l g r o wt h cyc l e s a re bo t h i n f l ue nced by p h o t ope r i od , b u t n o e v i d ence sugg e s ts t hat s e x h o rmones d i re c t l y a f f e c t woo l g r owt h o t h e r t h an t h r o ug h a r e s ponse i n f e e d i nt a k e . Fe rgus o n ( 1 9 5 1 ) f ound n o e f f e c t o f o r c h idec :omy o n wo o l gr owt h o r f r om t e s t os t e r o n e i mp l a n t s i n sheep f e d a c ons ta nt rat i o n . S l e n a nd C onne l l ( 1 9 5 8 ) f o und n o e f f e c t s due t o t he admi n i s t rat i o n o f t e s t o s t e r one o r p r oges t e r o n e . A l t h o ugh S le n and Conne l l f o u nd o e s t rad i o l t o r e duc e l e ng t h 5 6 gr owt h r a t e , i t i s d i f f i c u l t t o s e pa r a t e d i r e c t e f f ects a nd t h o s e med i at e d t h r o ug h accompa ny i ng changes i n t h e p i t u i ta ry a nd a d r e na l g la nd s . Drape r e t a l . ( 1 9 6 6 ) f o und t hat o e s t r ad i o l r ed uced woo l gr owt h o n l y whe n f e ed was r e s t r i c t ed . Fe r gu s o n e t a l . ( 1 9 6 5 ) conc l uded t hat o e s t r ogens , a nd r ogen s a nd p r oge s t e r o n e , a t phys i o l og i ca l c o nc e n t ra t i o ns , a r e u n l i k e ly t o a f f e c t woo l gr owt h . Othe r p i t u i ta r y h ormones The r e i s n o e v i d e nce t ha t oxytoc i n o r vas opr ess i n , s ecr e t ed by t he pos te r i o r l o be o f t h e p i tu i ta r y , a f f ect woo l g r owt h ( Wa l l ace 1 9 7 9 ) . F e rguson e t a l . ( 1 9 6 5 ) s howed e v i d e nce t ha t a p i tu i ta r y f ra c t i o n , d evo i d o f o t h e r p i t u i ta ry h o rmo ne act i on was a b l e t o s t i mu l a t e wo o l gr owth i n t h e hypophys e c t om i z e d s he e p . 5 . 1 . 4 . 2 Ca t e c h o l am i n e s Cat e c h o lami ne s s uc h a s a d r ena l i ne a nd n o rad r ena l i ne a r e s e c r e ted i n r e s ponse t o ne ura l s t imu la t i on . Fe r gus o n ( 1 9 4 9 ) , s h owed t ha t wo o l gr owth i nc r ea s ed a f te r sympa thectomy i n s he e p . B l o od f l ow t o t he s k i n i nc reased due t o vas od i l a t i on , a f t e r t h e vas o c o ns t r i ct i ng e f f e cts o f n o rad r e na l i ne f r om t he ne rve e nd i ngs c eased . Adr e na l e c t omy d o e s n o t a f f e c t wo o l gr owt h ( Fe r gus o n e t a l . 1 9 6 5 ) but t h e amoun t o f n o rad r e na l i ne s e c r e ted a t t h e s ympa t he t i c n erve e nd i ng c o u l d c o nt r o l woo l g r owth t h r ough vas o c o ns t r i c t i on o f t h e s k i n ' s b l o od ve s s e l s ( Wa l lace 1 9 7 9 ) . O the r unpub l i shed e v i de nc e , c i t ed by Wa l l ace ( 1 9 7 9 ) , i nd i cated that i n trad e rma l i n j ec t i o ns o f adr e na l i ne o r n o r ad r e na l i ne d ep r e s s t he r a t e o f uptake o f L 3? S -cys t i ne i n t o woo l f i br e s p l ucked f r om a r o und i n j e c t i o n s i tes . T h e r e su l ts s ugge s ted t ha t i t s e f f e c t was v i a a t emporary r educt i on i n b l o od f l ow . 5 7 5 . 1 . 5 R o l e o f t he p i ne a l g l a nd i n wo o l gr owth cyc l e s Many o f t he r e v i e ws o n h o rmon e s a nd wo o l gr owt h have i gn o r e d t h e p i ne a l g land , a l though p i ne a l e c t omy has be e n u s e d i n s t ud i e s w i t h s h e e p s i nc e t h e l a t e 1 9 6 0 ' s . Ex i s t e nce o f t h e p i ne a l g la nd has bee n r e cogn i ze d f o r c entur i e s b u t s e r i o us e nd oc r i n o l og i ca l wor k w i t h t h i s g land bega n o n l y i n t h e 1 9 5 0 ' s . P i nea l r e s ea r c h , t h o ug h far f r om comp l e te , has b egun t o el uc i da t e the mec ha n i sms o f p h o t ope r i od i c c o nt r o l o f e nd oc r i ne sys t ems a nd t he i r r e l a t i o ns h i p t o cyc l e s o f wo o l /ha i r gr owt h a nd r e pr oduct i on . 5 . 1 . 5 . 1 The d i s c ove ry o f p i ne a l f unct i o n P r i or t o 1 9 5 4 , t h e t wo c ommo n l y k n own facts a b out t h e p i ne a l g la nd we r e t ha t i t t e nds t o ca l c i fy , a nd thus can be used a s a l a ndma r k i n bra i n X - rays , a nd t ha t Desca r te s had bes t owe d o n i t t h e h onour o f be i ng the s ea t o f man ' s s o u l . O the r w i s e i t was gene ra l ly be l i eved t o be a f u nct i on l e s s , e vo l u t i o na ry ve s t i ge . Bra i na rd ( 1 9 7 8 ) r e v i ewe d p i ne a l r e s e a r c h i n what he r e f er s t o a s " the de cade o f t ra ns f o rma t i o n " f r om 1 9 5 4 t o 1 9 6 5 . I nt e r e s t i n t h e p i ne a l g l a nd i nc r eased a f te r t h e pub l i ca t i on o f a n e xt e ns i ve r ev i e w ( K i tay a nd A l t schu l e 1 9 5 4 ) wh i c h s umma r i ze d mor e t han 1 8 0 0 r e fe r e nces . They c onc l ud e d that t he p i nea l was i nvo l ve d i n g onada l f unct i on , i n l i gh t ? i nduced p i gmen ta t i on r e s pon s e s a nd p o ss i bly i n bra i n ? beha v i o r a l a noma l i e s . I nd e pe nd e nt ly , a nd unawa r e o f K i tay a nd Al t schul e s ' b ook , L e r ne r began i nves t i gat i o n s i n 1 9 5 1 t o i s o late a p i nea l h o rmo ne . H i s wo r k was ba sed o n a n e a r l i e r r e p o r t ( McCo rd and Al l e n 1 9 1 7 ) t hat p i n e a l e xt r ac t s c o un t e racted t h e dar k e n i ng e f f e c t o f me lanoph o r e s t i mu l a t i ng h o rmone i n f r og s k i n . H i s publ i ca t i on ( Le r n e r e t a l . , 1 9 5 8 ) i d e nt i f i ed a po t e n t p i ne a l hormone , me l a t o n i n , a s t h e me t h o xy d e r i va t i ve o f s e r o t o n i n , a nd s e t i nt o mo t i on a g r eat numbe r o f s t ud i e s o f p i ne a l s t ucture a nd f unct i o n , t h e mome ntum o f wh i c h has n o t v i s i b ly d i mi n i s he d . By 1 9 6 5 , t h e i nn e r va t i on o f t h e p i ne a l by sympa t he t i c ne rve s ; the d e p r e ssant act i o n o f me l a t on i n on thyr o i d s e cr e t i on ; t h e l i gh t d e pe nda n t n a tu r e o f p i nea l e nzyma t i c r eact i on s a nd t he a b i l i ty o f p i ne a l e c t omy t o remove s h o r t p h o t o pe r i od i nduced g onada l changes we r e we l l e s tab l i s hed , s uc h t hat the p i ne a l was t e rme d a " ne u r o e nd ocr i ne t ransd uc e r " by Wur tma n a nd A l e x r od ( 1 9 6 5 ) . 5 8 Wur tma n ( 1 9 7 8 ) e mphas i zed t ha t t he mos t r e g r e ttab l e a s pe c t o f muc h p i nea l r e s ea rch had be e n t h e c oncentrated u s e o f r a t s a s t he e x pe r ime n t a l a n ima l s . S e l e c t i ve br e e d i ng a nd i nb r e ed i ng o f t h e s e s t oc k s have r e s u l ted i n an a n i ma l o f neg l i g i b l e p h o t o pe r i od i c s e ns i t i v i ty , a nd t here f o r e i t may n o t c o ns t i tu t e t h e mos t appr opr i a t e a n i ma l mode l . O t h e r s eas o na l a n i ma l s may have e l i c i te d be t t e r r e s u l ts . T h e f a c t t hat muc h e v i d e nc e a r i s e s f r om l o ng-day b r e ed i ng s pe c i e s has a l s o , at t ime s , c o n f used t he s t o r y o f t h e r o l e o f me l a to n i n i n r e pr oduct i on a nd ha i r gr owt h . Exce l le n t r e v i ews o f p i nea l a na t omy a nd funct i o n can be f o und i n N i r , Re i te r a nd Wur tman ( 1 9 7 8 ) a nd Re l k i n ( 1 9 8 3 ) . Many o f t he s e r e v i e ws c oncentrate on g o nad o tr o ph i c r e s po n s e s i n l a b or a to ry a nd w i l d a n i ma l s , a nd a pp l i ca t i ons t o h uman phys i o l ogy . Al t h ough the p i ne a l i nd o l e , me laton i n , has r e c e i ve d mos t o f t h e pub l i c i ty o t h e r p i ne a l i nd o l e -ami n e s a nd p o lypept i d e s a r e s ec r e t ed b y t h e p i ne a l g la nd b u t t he i r phys i o l og i c a l act i ons have n o t b e e n a s w id e l y s t ud i ed . 5 . 1 . 5 . 2 Me l a t o n i n a nd pho tope r i od i c t i me -measureme n t I t may be wor thwh i l e t o spend a sma l l amount o f t i me o ut l i n i ng the ways i n wh ich me l a t o n i n i s i nvo lved i n pho t ope r i od i c t i me -measureme n t . Two d i s t i nc t hypo th e s e s have be e n pr o p os e d . I n t h e f i r s t , i t i s the t o ta l d urat i o n 5 9 o f me laton i n e xpos ur e e a c h day wh i c h d i c tat es t he r e s po n s e . The s e c o nd hyp o t he s i s has t h e t im i ng o f a da i ly r hythm i n s e ns i t i v i ty t o me l a t o n i n r e la t i ve t o the pe r i od o f me l a t o n i n s e c r e t i on d e t e rm i n i ng t he r e s pons e . The f i r s t hypo the s i s i s s upp o r ted by e xp e r ime nts i n wh i ch e x og e nous me l a t o n i n has b e e n g i ve n t o i nc r ease t h e d u r a t i on o f e xposure t o me l a t o n i n . Ca r te r a nd Go ldma n ( 1 9 8 1 ) a nd Go l dman ( 1 9 8 2 ) , wor k i ng w i t h D j ungar i a n hamps t e r s , a nd B i t tma n e t a l . ( 1 9 8 2 ) w i t h S u f f o l k s h e e p have u sed p r ogrammed i n f us i on s o f me l a t on i n t o s h ow t hat whe n b l o o d l e ve l s a r e c ont i n ua l l y e l e va te d f o r mor e tha n 1 2 h o u r s e ach day f or s eve r a l we e k s , a s h o r t d ay r e sponse i s s e e n . Remembe r that me la t on i n i s r e l eased f r om the p i ne a l d u r i ng dar k ne s s h our s . I f b l o o d l eve l s a r e e l e vated f or s h o r t pe r i ods , even i f mo r e t h a n o nc e p e r day, t hen a l ong day r e s ponse i s s e e n . Tamar k i n e t a l . ( 1 9 7 6 ) s ho wed that t he t i mi ng o f i n j e c t i on s was c ruc i a l , w i t h a f t e r n o o n r a t he r t han mo rn i ng e xt e ns i o ns be i ng r e qu i r ed . A lme i da a nd L i nc o l n ( 1 9 8 2 ) s upported t h e i nvo lvme nt o f c i r cad i a n r hythms . R o l lag and N i swe nd e r ( 1 9 7 6 ) a nd K e nnaway e t a l . , ( 1 9 8 3 ) f o und that me l a t o n i n s e c re t i on c ont i nued t o '' f r e e r u n " t o a 2 4 hour r hythm i n c on s tant dark ne s s , but was s uppr e s s ed by c on t i n u ous l i gh t . T i mi ng e f fe c ts have a ls o be e n noted by Wa tson-Wh i tme ye r a nd S t e t s on ( 1 9 8 3 ) . I n p i nea l e ct omi zed hampst e r s n o t i me e f f ec t was obse rved ( Tama r k i n e t a l . , 1 9 7 7 ; Go ldman e t a l . , 1 9 7 9 ) . 5 . 1 . 5 . 3 Me l at o n i n a nd ha i r , woo l a nd h o r n gr owt h cyc l e s P i nea l i nvo lveme nt ( v i a me l a t o n i n ) i n the r egu la t i o n o f ha i r gr owt h i n m i c e was d emo n s t r ated b y Houssay e t a l . ( 1 9 6 6 ) who obs e rved that p i ne a l e c tomy acce l e rat ed the passage o f waves o f ha i r growt h , a nd s ubcutane ous me l a t on i n i n j ec t i on s t o i n tact o r p i nea l e c t omi z ed a n i ma l s r e tarded the m . Rus t and Meyer ( 1 9 6 9 ) i nduced me l a t o n i n i mp lanted wease l s t o mou l t t o a w i n t e r c oa t whe n a n i ma l s we r e he ld i n p h o t o pe r i ods wh i c h pr omo t ed s umme r c oa t f o rma t i on i n c o n t r o l a n i ma l s . S i mi lar l y , me l a t o n i n i mp lanted wh i te ? f oo t ed m i c e h e l d i n s ummer e nv i r onmenta l cond i t i ons und e rwe n t an " a u tumn " mou l t to w i n t e r c oa t s ( Lynch a nd Eps t e i n , 1 9 7 6 ; H eath a nd L ynch , 1 9 8 1 ; 1 9 8 2 ) . 6 0 H o f fmann ( 1 9 7 3 ) d e laye d , b ut d i d n o t p r eve n t , a s pr i ng mou l t i n w i n te r -ma i nta i ne d , me l a t o n i n - i mp lanted , S i be r i a n hamps t e r s e xposed t o l o ng p h o t o pe r i ods . The r e p laceme n t c oa t , a l t hough c l o s e r t o s umme r s t r uc t ur e , was wh i t e ( w i nt e r ) c o l o u r ed . I n a n i ma l s ma i n ta i ne d o n s h o r t p h o t o pe r i ods t he r e we r e n o d i f f e r e nc e s be tween me l a t on i n ? t r ea te d a nd c o nt r o l a n i ma l s . L oga n a nd Weathe r head ( 1 9 8 0 ) c onc l uded f r om s tud i es o f c u l t u r ed hampst e r f o l l i c l e s , t h a t p i ne a l i nd o 1 e -am i nes may a c t d i r e c t ly o n me lanoge ne s i s , b u t o t h e r pho t o pe r i od r e l a t ed e f f e c t s o n ha i r gr owth a r e l i k e ly med i a t e d v i a the p i t u i ta ry a nd o t h e r e ndocr i ne o r gans . M i nk , s ubcutaneous l y i mp l a n t e d w i t h me l a t on i n , we r e d e l ayed i n t h e s pr i ng mou l t o r we r e e a r l y i n t he autumn mou l t a l s o d emonst r a t i ng t he a b i l i ty o f me l a t on i n t o mimi c t h e act i on o f s h o r t days ( Al la i n a nd R ouge o t , 1 9 8 0 ; Al la i n e t a l . , 1 9 8 1 ; R ouge o t e t a l . , 1 9 8 4 ; R o s e e t a l . , 1 9 8 4 ) P i ne a l r e s ea rch i n s h e ep has c o nc en t ra t ed o n i ts r o l e i n s e a s o na l r e p r od uc t i on and t he o ns e t o f puberty . Woo l g r owt h r e s e arch has bee n q u i te i ncomp l e te . I t s e ems r e g r e t t a b l e t ha t woo l g r owth s t ud i e s have not b e e n c o up l e d w i t h mos t o f t h e s e r e produc t i ve pr o j e c ts . L i nc o l n e t a l . ( 1 9 8 0 ) , us i ng S oay r ams , s t ud i ed t he e f f e c t s o f s upe r i or c e r v i ca l gang l i o n e c t omy ( wh i ch d e s t r oys i nne r va t i on o f t he p i nea l g l a nd ) o n wo o l and h o rn gr owt h i n a l t e r na t i ng 1 6 -we e k pe r i ods o f s h o r t ( 8 L : 1 6 D ) a nd l ong ( 1 6L : 8 D ) days f o r t hr e e yea r s . I n i ntact rams b o t h wo o l a nd h o r n gr owth f o l l owed t he i mposed l i ght reg ime s . Dur i ng s h o r t days , t he r a t e o f woo l a nd h o r n gr owt h dec l i ne d a nd 6 1 d u r i ng l o ng days , mou l t i ng o f the o ld c o a t c o i nc i d e d w i t h t he p ha s e o f i nc r eas i ng wo o l gr owt h . I n gang l i one c t omi zed rams , woo l a nd h o r n g r owt h d id n o t r e s pond t o pho t o pe r i od i c changes but , r a t he r , f o l l owed l ong t e r m changes i n p lasma l e ve ls o f va r i o u s p i t u i ta ry hormon es . O r a l l y admi n i s t e r e d me l a t on i n has be e n s hown t o i nd uce a n t l e r mat ur a t i on i n wh i t e - ta i l ed d e e r ( Bube n i k , 19 8 3 ) . L i nc o l n ( 1 9 8 3 ) n o t e d t ha t a l though me l a t o n i n was a c o nve n i e n t me thod o f i nd uc i ng w i n t e r changes d u r i ng the s umme r , the r e ve r s e e f f e c t s we r e not s o s i mp l y a c h i eved . Acco r d i ng ly , s ome me t hod o f b l oc k i ng t he a c t i o n o f me la t o n i n i n t h e bra i n , o r t o i nh i b i t i ts r e l ea s e was ne eded t o c ou n t e ract t he e f f e c ts o f natur a l w i n t e r . 5 . 1 . 5 . 4 P i ne a l -h o rmo n e i nt e ract i on s T h e o ve r a l l e f f e c t o f t h e p i nea l g l a nd o n thyr o i d f unct i o n wou l d appear t o b e i nh i b i t ory . S e ve r a l s t ud i e s w i t h l ab o rat o ry s p e c i e s , r e v i e wed by Re l k i n ( 1 9 8 3 ) s h owed tha t t h e admi n i s t r a t i on o f me l a t o n i n t o r a t s r educed t hyr o i d we i ghts a nd d e c r e a s e d t h e secr e t i on rate o f thyr ox i ne . P i n e a l ect omy l e ads t o t hyr o id hype r t r ophy a nd i nc r eased t hyr o x i ne s e c r e t i on . The s e wor k e r s t h ough t t ha t me l a t o n i n a c t ed d i r ec t l y o n t h e t hyr o id . O t h e r s tud i e s i n Re l k i n ' s r e v i e w , have s ho wn me lat o n i n t o act o n the hypo t ha lamic ? p i t u i tary l e ve l whe r e TRH r e l ease and s ubsequent e f f ects o n T S H we r e r educed b y t he admi n i s t ra t i o n o f me l a t o n i n . O ther s tud i e s f ound a p o s i t i ve f e edback o f t h e t hyr o i d o n t h e p i ne a l . I n g e n e ra l , l ong days s h ou ld r e s u l t i n h i ghe r t hyr o x i ne l e ve l s t h an s h o r t days . Th i s has be e n ver i f i e d by Ryde r ( 1 9 7 9 ) a nd L i nc o l n e t a l . ( 1 9 8 0 ) . The e f f ect o f t h e p i nea l o n the adr e na l s i s unc l e a r a nd may be s pe c i e s d e pe ndant . I n rats , the p i ne a l i nh i b i ts both a d r e n a l c o r t i co s te r o i d synthes i s and s e cr e t i on , t h e lat t e r d ec r ease be i ng pa r t ly t he r e s u l t o f acce l e rated d egradat i on . 6 2 Me l a t o n i n a ppears to e xe r t i t s e f f e c ts b o t h d i r e c t ly a nd v i a t h e f e e d back r e s ponse o n ACTH . The e f f e c t s o f me la t o n i n o n d i ur na l va r ia t i o n have be e n c on f l i ct i ng ( Re lk i n , 1 9 8 3 ) . The s e a s o na l e f f e c t s o n s e r um c o n c e n t ra t i on s o f g l uc oc o r t i c o i d s i n l a rge a n ima l s a r e n o t we l l e s t a b l i s hed owi ng t o c o n f ound i ng e f f ects o f s t r e s s a nd d i ur na l va r i a t i on ( Th un e t a l . , 1 9 8 1 ) . L o ng days l o we r e d s e r um g 1 uc oc or t i co i d s i n cat t l e ( Le i n i ng e t a l . , 1 9 8 0 ) a nd i n s he e p ( Br i nk l ow a nd F o rbe s , 1 9 8 4a ) . P i ne a l e c t omy r e duced t h i s d ec l i ne i n s he e p ( Br i nk l ow a nd For be s , 1 9 8 4 b ) . O t h e r s t ud i e s have r epor ted l i t t l e o r n o ph o t o pe r i od i c e f f e c t s i n s h e e p ( Ke n naway e t a l . , 1 9 8 1 ; L i n c o l n e t a l . , 1 9 8 2 ) . L o ng days e l e va t ed s e rum g l uc oco r t i c o i d s i n p i gs ( Ba r n e t t e t a l . , 1 9 8 1 ; K r a e l i ng e t a l . , 1 9 8 3 ) . P h o t o pe r i od i c e f f e c ts o n g r owt h h o rmo ne a l s o var y g r ea t ly be t we e n r e po r ts a nd be twe e n s pe c i e s . I n rat s , e n hanced p i ne a l a c t iv i ty reduced t he pr oduc t i o n a nd re l ease o f g r owth h o rmon e i n s ome s t ud i e s ( Re l k i n , 1 9 8 3 ) . I n c a tt l e , p h o t o pe r i od has n o t had a ny d emo ns tra t i ve e f fe c t o n g r owt h h o r mo ne ( Pe te r s a nd Tuck e r , 1 9 7 8 ) . I n n o n -pr egnant g oa t s , g r o wt h h o r mo ne c once ntra t i o ns we r e h i ghe r i n l o ng tha n i n s h o r t day t r eatments ( Te r gu i e t a l . , 1 9 8 4 ) . Res u l t s f r om d e e r a r e c on f l i c t i ng . P r o lac t i n i s c ons i d e r ed t o be t h e me tabo l i c hormone mos t r e s po ns i ve t o s easona l i n f l ue nces ( Tuck e r , 1 9 8 2 ) . S t ud i e s i n r a t s a nd m ice , r e v i ewe d by Re l k i n ( 1 9 8 3 ) have p r oduced c o n f l i c t i ng r esu l ts . Und e r natura l c ond i t i ons , e le va t e d s e r um c onc en t ra t i ons o f pr o l a c t i n have be e n a s soc i a te d w i t h s pr i ng a nd s umme r a nd d e p r e s s ed concent r a t i o ns have be e n o b s e rved d u r i ng autumn a nd wi nte r i n cat t l e ( K opr owsk i a nd Tuc k e r , 1 9 7 3 ) , s he e p ( Ravau l t , 1 9 7 6 ; Mun r o e t a l . , 1 9 8 0 ; B a s e e t a l . , 1 9 8 2 ) , goa t s ( Bu t t l e , 1 9 7 4 ) , d e e r ( M i r a r c h i e t a l . , 1 9 7 8 ) a nd wi ld p i gs ( Rava u l t e t a l . , 1 9 8 2 ) . P r o l ac t i n c o n c e nt r a t i ons i n he i fe r s , und e r c onstant photope r i od , r i s e 6 3 a nd fa l l w i t h s i m i lar cha nge s i n tempe ratu r e ( We t t ema n a nd Tuck e r , 1 9 7 4 ) . Bu l l ca lve s , ma i nta i ned a t c onstant t empe rature , a l s o va r i e d p r o l ac t i n c o nce n t ra t i ons w i th day l engt h . S i m i l a r s t ud i e s w i t h sheep have s h own t ha t p r o lact i n c o nce n t ra t i o ns i nc r eas e w i t h i nc r ea s e d dayl e ng th ( Pe 1 l e t i e r , 1 9 7 3 ; F o r b e s e t a l . , 1 9 7 5 ; 1 9 7 9 ; L i nc o l n e t a l . , 1 9 7 8 ) . S upe r i o r gang l i o ne c t omy r educes o r r emoves t he p h o t o pe r i od i nduced p r o lact i n r e s ponse i n s h eep ( Ba r r e l l a nd Lapwo od , 1 9 7 9 ; B r o wn a nd F o rbe s , 1 9 8 0; L i nco l n e t a l . , 1 9 8 2 ; B r i nk l ow a nd Forbe s , 1 9 8 4 a?) . C ont i nuous l i gh t i s n o t n ecessary f o r s t i mu la t i o n o f p r o l ac t i n r e l e a s e a s a p h ot o i nduc i b l e p ha s e o f pr o l ac t i n synthe s i s e x i s t s a bout 1 7 h ou rs a f t e r dawn i n s he e p ( Rava u l t a nd Or tavant , 1 9 7 7 ; T h i mo n i e r e t a l . , 1 9 7 8 ; Schanbach e r a nd Cr ous e , 1 9 8 1 ; B r i nk l ow a nd F o rbe s , 1 9 8 4 a . b ) . 5 . 1 . 5 . 5 Summary T h e mec ha n i sms t h a t r e gu la t e t h e p h o t ope r i od i c r hythm o f wo o l gr owt h i n s h e e p a r e poo r ly und e r s t o o d . Wha t d o e s s e em l i k e l y i s t hat t he p i ne a l g l a nd i nt e racts w i th t h e e nd oc r i ne s ys tem t o a l t e r t h e c i r c u la t i ng l e ve l s o f me tabo l i c h ormo nes wh i ch t h e n a f f e c t wo o l g r owth . Exact ly wh i ch h or mones a nd wh i ch aspects o f t h e i r l eve l s a r e impo r tant have n o t bee n c lea r l y s hown . F r om t h e e v i d e nce pr e s en t ed , t h e t hyr o i d g land , p oss i b ly i nt e r ac t i ng w i t h the ad r e na l s , s e ems the mos t l i k e ly i n f l ue nce on seas ona l wo o l gr owt h . The r o l e o f p r o lact i n c e r ta i n l y n e eds t o be mo r e c le a r ly de f i ne d . S t ra i ns o f s h e e p , w i t h d i f f e r i ng p h o t ope r i od i c s e ns i t i v i ty s ho u l d be s t ud i e d t o d e te rmi ne a t wh i c h l e ve l t h i s s e ns i t i v i ty i s b e i ng ma n i f e s t . I s i t a d i f f e r e nce i n p i n ea l a c t i v i ty , a d i f f e r e nce i n t h e r e s ponse o f t he e nd oc r i ne syst em t o p i ne a l s e c r e t i ons , o r i s i t a t t h e l eve l o f t h e pr oduct ive t i s s ue s? 5 . 1 . 6 Measur i ng t h e s e a s o na l i ty o f woo l gr owth 6 4 T h r e e ma i n techn i ques e x i s t f o r measur i ng wo o l g r owt h o ve r s h o r t p e r i ods . Who l e a n i ma l s h e a r i ng i s i nappr o pr i a t e a s i t may comp l i cate na tur a l cyc l e s w i t h the add i t i ona l i n f l u e n c e s o f t emperature r e gu l a t i on , a l te re d i ntak e , and damage t o t h e s k i n . Changes i n t h e r a t e o f woo l gr owt h i n e xpe r ime nta l s he e p a r e usua l ly mea s u r e d by c l i pp i ng t he woo l a t r eg u l a r i nte rva ls f r om a d e f i ne d a r e a o f s k i n ; b y dye -ba nd i ng t h e woo l a t s k i n l eve l w i t h p e rma ne n t dye ; o r by l a be l l i ng t h e wo o l w i t h 3 5 8 - la be l l e d cys te i ne v i a i n t ravenous i n j e c t i o n . Al l me t h ods have i nh e r e n t adva ntages a nd d i sadva ntages and t he e f f i cacy may d e pe nd o n t i me i n te rva l s i nvo l ve d a nd t h e u n i f or mi ty o f f i br e gr owt h i n t h e f l e ec e . 5 . 1 . 6 . 1 The tatto o ed pa t ch t e c h n i que The tat to oed pat ch t e chn i que i nv o lve s r egular ( us ua l ly mon t h l y ) c l i pp i ng o f a l l wo o l o n a d e l i nea ted pa t ch ( a ppr o x i mate ly 1 0 0 cm2 ) . C o n t i n u o us samp l i ng o f t he p r od uc t i on o f the same f o l l i c l e s i nc reases the accuracy o f w i t h i n s h e ep c ompar i s ons . The who l e f le ec e : pa t c h p r oduct i on can be used t o pa r t i t i o n who l e f l e ece gr owt h , wh i c h i s a pp r opr i a t e f or b o th wi t h i n - a nd be tween -an ima l c ompa r i s ons . Fa i l u re t o r e ta i n a c o ns t a n t pa t ch s i ze a l te r s t he r a t i o o f pat ch : f l e ece product i on . A l t hough c l i pp i ng pe r s e had n o e f f e c t o n the r a t e o f woo l g r owth o n mids i d e pat che s , D own e s a nd Lyne ( 1 9 6 1 ) a nd Wod z i c ka -Tomaszews ka a nd B i gham ( 1 9 6 8 ) c onc luded t ha t l oc a l c oo l i ng o f the pa tch c o u ld r e duce wo o l gr owt h and e xagge rate the s eas ona l amp l i t ud e o f wo ol growt h . H oweve r , i n t h e l a t te r o f t h e s e s t ud i e s t h e who l e an ima l was s h o r n e ve ry 1 6 wks , a nd t h i s wo u ld prevent the r e s t o f t h e f l e e ce f r om i nsu la t i ng t he pa tch . The pat ch t e chn i que a l s o lags be h i nd f o l l i c l e output d ue to the 5 - 1 0 day eme r ge nc e t i me o f t h e f i br e ( Downes a nd S ha r ry , 1 9 7 1 ) . 6 5 5 . 1 . 6 . 2 Dye -ba nd i ng Dye -band i ng was d e ve l o pe d by Chapman a nd Whe e l e r ( 1 9 6 3 ) u s i ng a wea k aque o us s o l u t i o n o f Dura f u r B la c k R wh i c h has t h e capac i ty t o d ye gr easy wo o l a t s k i n t empe ratur e . Dye ? band i ng a ls o l eaves the p r op r i oc l i ma te o f t he s k i n u nd i s t ur bed . As d i s cussed by S qu i r e s ( 1 9 6 4 ) and C la r k a nd K o hn ( 1 9 6 4 ) a c or r e la t i o n o f 0 . 8 8 - 0 . 9 7 e x i s t s be twe e n dye ? band i ng a nd c l i pp i ng r e s u l ts i n Mer i no s h e e p . Dye -band i ng g i ve s easy read i ngs o f f i br e l e ng t h and i nt e rva l d iame te r s c o u l d b e obta i ne d b y samp l i ng dyed s t ap l e s . H oweve r , Langlands a nd Whe e l e r ( 1 9 6 8 ) a nd Whe e l e r e t a l . ( 1 9 7 7 ) e mphas i ze d t h e d i f f i c u l ty o f p r e d i ct i ng the we i gh t o f woo l f r om l e ng t h a nd d i ame t e r measu r eme nt s . The t echn i que i s a l s o a f f e c t ed by s hedd i ng , wea r a nd t h e t e ndency o f i nd i v i d ua l f i br e s i n t he s t a p l e t o g r ow a t d i f fe re n t r a te s . Whe e l e r e t a l . ( 1 9 7 7 ) s ugges t t ha t t h e t e c h n i que may be unsa t i s fac t o ry f or c oa rs e , o p e n o r med u l lated f l eeces . 5 . 1 . 6 . 3 Rad i o i s o t ope l abe l l i ng Labe l l i ng o f wo o l w i t h rad i o i s o topes was f i r s t d e sc r i bed by D owne s a nd Lyne ( 1 9 5 9 ) . Fur t h e r e va l ua t i on o f t h i s rad i oautograph i c t e c h n i que us i ng 3 5 S -cys t e i ne was ca r r i e d o u t b y D ownes a nd Lyne ( 1 9 6 1 ) a nd Down e s a nd S ha r ry ( 1 9 7 1 ) . T he advan tage o f t he t echn i qu e s l i e s i n ve ry s ho r t t e rm s t ud i e s i n wh i ch accurate i n f or ma t i on o n da i ly i nc o rp o ra t i on o f nu t r i e n ts i nt o f i br e s i s r e q u i r ed . As t h e wo o l i s l abe l l e d i n t h e f o l l i c l e , samp l e s f or s t udy a r e n o t r emoved unt i l s ome t i me a f t e r the e nd o f the e xpe r i me n t . P e r i ods a s s h o r t as f our days c a n b e measured . The d i sadvantage , as i d e f r om c os t , i s t ha t measureme nts a r e r e q u i red o n s e ve ra l h und r e d i nd i v i d ua l f i br e s as s ome f i br e s grow at 3 x t h e r a t e o f o t he r s . The o t he r s ho r tcomi ng i s t hat i n f us i ons o f labe l l e d cys t e i ne may t h ems e lves a l t e r t h e n orma l gr owth o f f i b r e by p r ov i d i ng s ubstrates a t r a t e s o r l eve ls n o t 6 6 phys i o l og i ca l l y n o rma l . 5 . 1 . 7 . S ummary T h e a nnua l va r i a t i on i n wo o l g r owth i s s i gn i f i ca n t f or a numbe r o f r eas o ns . T h e s eas o na l i ty o f woo l gr o wt h a ppear s t o b e c o nt r o l l e d by a numbe r o f phys i o l og i ca l s ys t ems wh i c h u l t i ma t e l y a r e r e f l e c te d i n t h e e nt i re a n i ma l . H o rmo na l i nvo l vme nt i n t h e a n n u a l cyc l e i s n o t l i k e l y l i mi ted t o l oca l e f f e c t s o n t he ski n , b u t i s i nvo lve d o n a l a rge r sca l e w i t h i nt a k e a nd me tabo l i c f unct i on . S tud i e s d ea l i ng wi t h d i f f e r e n t breeds , o r s e l e c t ed l i ne s may b? a f f e ct ed by s eas o na l d i f f e r e nc e s i n the r e l a t i ve l eve l o f pe r f o rma nc e . S eas ona l i ty o f woo l gr owt h i s a l s o l i k e l y r e f l e ct ed i n o t h e r s e a s o na l t r a i t s s u c h a s r e pr oduct i on , e f f i c i e ncy a nd i nta k e . The und e r l yi ng s e a s o na l i ty o f many a spects o f s he e p pe r f o rma nce , a nd d i f f e re nces i n s e a s o na l r e s ponses be twe e n g r o ups , i s e s s e n t ia l t o s t udy i ng mos t a spects o f s h e e p pe r f o rmance . 5 . 1 . 8 Obj e c t i ve s o f t h e c ur r e n t t r i a l The o b j e c t i ve s o f t h e c ur r e n t t r i a l wer e : 1 ) t o d e te rmi ne t he c o r r e lated r e s ponses i n the s e a s o na l i ty o f wo o l gr owth t o s e l ec t i on f or h i gh h ogge t g reasy f l e e c e we i gh t ; 2 ) t o quan t i fy t he i mp o r tance o f s ources o f va r i a t i on s u c h a s s e x , b i r t h rank , dam age , a nd s e l e c t i on l i ne ; a nd , 3 ) t o pr ov i d e a database f o r l a t e r compa r i s o n w i t h s e a s o na l i ty o f r e pr od uc t i o n , t h e e s t ima t i o n o f f e e d i n ta k e a nd t he measureme n t o f s t a p l e s t r e ngth . 5 . 2 Ma te r i a l s a nd Me t hods 5 . 2 . 1 Exper i me n t a l p l a n 6 7 The s t udy was c o nd uct ed be twe e n Decembe r 1 1 t h , 1 9 8 4 a nd Oct o b e r 2 3 r d , 1 9 8 5 o n 1 9 8 4 b o r n ram a nd ewe hogg e t s f r om t he FW a nd C l i ne s . The se s h e ep we re a b out 4 mon t hs o ld a t t h e s ta r t o f t h e t r i a l a nd 1 4 months o l d a t the c o nc l us i o n . O n De cembe r 1 1 t h , 1 9 8 4 woo l was r emoved f r om a r i ght m ids i d e patch ( appr o x i ma te ly 8cm by 8cm ) o n a l l ava i la b l e F W a nd C lambs . F l e e c e s we r e we i ghed a t l amb s he a r i ng o n D ecembe r 1 2 , 1 9 8 4 . On D ec ember 1 3 t h , 1 9 8 4 a dyeband was a pp l i ed a l o n g a n 8 cm l i n e a ppr o x i ma t e ly 2 c m d i r e c t l y a bove t h e d o r sa l edge o f t h e m i d s i d e patc h . Woo l samp l i ng , d ye ba nd i ng a nd meas ureme nts o f l i ve we i gh t we r e c onduct ed e ve r y 4 we e k s be twe e n lamb a nd h ogget s hea r i ng o n Oc t ob e r 2 3 r d , 1 9 8 5 . O n l y t h o s e s he e p wh i ch s u rv i ved u nt i l t h e c on c l us i on o f t h e e xpe r i men t we r e c ons i d e r ed i n t h e a na lys i s , a s pa tch p r oduct i o n was used t o par t i t i on t h e hogget f l e ec e we i gh t i n t o 2 8 - day u n i ts . Comp l e t e mea s ur eme nt s we re a l s o needed f o r the e s t i ma t i on o f amp l i tude t r a i ts . T h r oughout t h e e xpe r i me n t s h e ep wer e l o s t d u e t o d e a t h a nd m i s p laceme n t . T he f i na l data s e t c o n s i s t e d o f 5 4 Cont r o l ( C ) a nd 7 2 F l e e c e we i gh t s e l e cted ( FW ) hogge ts . As e we a nd ram hogge ts we re g razed s epa ra t e l y r ams a nd e we s we r e samp l ed o n ad j acent days . 5 . 2 . 2 Sampl i ng r ou t i ne B e twe e n 1 5 : 0 0 a nd 1 7 : 0 0 h o u r s o n t h e day be f or e samp l i ng , h ogge ts we r e put i n a s hed o ve r n i ght w i t h o ut a ccess t o f ood o r wat e r . B e twe e n 0 8 : 3 0 a nd 0 9 : 3 0 hour s l i ve we i gh t s we r e ta k e n a nd r ec o r d ed o n a l l s he e p . Woo l s amp l i ng b ega n a t 0 9 : 3 0 h o u r s a nd c o n t i nued t h r oughout t h e day . Samp l i ng was c omp l e ted be twe e n 1 5 : 0 0 a nd 1 7 : 3 0 h ours a t wh i c h t i me the s h e e p we r e r e t u rn ed to pas t ur e . Each s he e p was la i d o n i ts s i d e o n a tab l e f or samp l i ng . <'rl?,qside po.tc.h, tben patch Woo l was c l i pped f r om t heAs i ze was mea s ured w i t h ca l pe r s . At n o t ime was t he pat ch a r ea d i f f i c u l t t o i d e n t i f y a nd 6 8 e xt r eme ca r e was t a k e n n o t t o e xpand the pa tch a r e a dur i ng c l i pp i ng . As a p r ecaut i on , t h e bounda r i e s o f e ach patch we r e de f i ne d by ta t t o o i ng i n m i d -Februa ry . The l e ngth o f wo o l g r own dur i ng t he p e r i od was measur ed t o t he nea r e s t mm as t he d i s tance be twe e n the s k i n a nd the b o t t om o f the p r e v i ous dye band on uns t r e tched s ta p l e s . A n ew dyeband was a pp l i e d a nd t he s he e p was r e l eased . Dye was p r e pa r ed accord i ng t o ( 1 9 63 ) and a pp l i ed w i th a s t a ndard Pas tueur p i pe t te drawn a l o ng t he s k i n . Excess dye was r emoved by s uc t i on a f t e r t h e p i pe t t e had be e n e mpt i ed o f r ema i n i ng dye . Appr o x ima t e ly . 5 ml o f dye was a pp l i ed t o each s he e p . 5 . 2 . 3 Samp l e pr o ce s s i ng a nd ca lcu late d va r i a b l e s Woo l samp l e s we r e c o nd i t i oned , we i ghed , s c oured a nd r e we i ghed a s o u t l i ne d i n chapter 4 . 2 . 3 e xcept t hat f i ne l y woven s i l k bags r e p l ac ed t h e me s h bags us e d i n t ha t e xpe r ime nt . Res i d ua l g rease measureme nts o bta i ne d f r om e t he r e xt ract i on o f s c o u r e d samp l e s y i e l d ed be twe e n 0 . 6 % a nd 2 . 2 % r e s i due i nd i ca t i ng t hat the s cour i ng procedure was adequa te . C l e a n samp l e s we r e t h e n carded on hand card e r s t o f r e e mat te d f i b r es . F i br e d i ame t e r was d e t e rmi ned by t h e A i r ? f l ow me t h od ( Ande r s o n , 1 9 5 4 ) . F i br e d i ame t e r was r ec o rd ed a s t he mean o f 2 r ead i ngs o n o ne subsamp l e . Dur i ng wi nte r months s ome o f t h e c l e a n samp l e s we i ghed l e s s t han 2 gms s o t he adapted a i r f l o w a ppa ratus a nd me t h od d e scr i be d by S umner ( 1 9 6 9 ) f or 1 gm samp l e s we r e used . F i br e d i amet e r o f t h ese " l i ght " samp l e s was r ecorded a s the mea n o f f o u r r ead i ngs o n o n e s u bsamp l e . Comp l e t e dye -ba nded s ta p l e s we re removed f o r r e f e r e nce f r om ha l f t he dye -banded a r ea o n May 3 0 t h a nd 3 1s t , 1 9 8 5 . The s e c o nd ha l f -yea r ' s d ye ba nded s tap l es a nd f u l l yea r dye ? banded s ta p l e s and s u r r ound i ng wo o l wer e r emoved a t t he l a s t s amp l i ng on the 1 6 t h a nd 1 7 t h o f Oc tobe r , 1 9 8 5 t o p r event c ontami na t i on o f t h e f l e e ce w i t h b lack f i br e s . T h e s e s t ap l e s we re s aved a nd u sed t o e s t i mate s ta p l e s t r e ngth ( Chapt e r 8 ) . C l e a n woo l gr owth ( g p e r day ) i n e ach month o f t h e yea r 6 9 was e s t ima ted f r om mon t h ly c l e an samp l e s . Eac h mon t h ' s c l ea n pa t ch woo l we i gh t was e x pr e s s e d as a pr opor t i on o f t he t o ta l c l e a n woo l g r own by t h e pa tc h . The c l ean f l e e c e we i gh t was t h e n mu l t i p l i ed b y e a c h mon t h ' s pr o p o r t i o na l g r o wt h . G r easy f l e e ce we i gh t was mu l t i p l i ed by t hese s ame p r o po r t i ons to e s t i ma t e t h e mon t h ly c ha nge i n g r easy f l e e ce we i gh t . These va l u e s wer e u s ed t o o bta i n f l e e ce - f r e e l i v e we i ghts a t each samp l i ng . L i ve we i ghts and l i ve we i g h t changes r epo r t ed s ubseque n t l y a r e o n a f l eece - f r e e bas i s u n l e s s o t h e rw i s e i nd i ca ted . O t h e r t r a i ts ca l cu l a t ed f r om t he data i nc l uded t h e amp l i t ud e ( H -L ) / ( ( H +L ) / 2 ) , whe r e H and L r e f e r t o t he h i ghe s t a nd l owes t va l u e s f o r a par t i c u la r t ra i t w i t h i n a n i ma l . Amp l i tud e s o f seas o na l changes i n c l ean woo l pe r d ay ( CPD ) , f i b r e d i ame t e r ( FD ) and l e ng t h pe r day ( LPD ) a r e d e s i gnat e d a s CPDAMP , FDAMP a nd LPDAMP . O t h e r va r iab l es i nc l uded t h e mon t h o f t h e l owes t va l u e s f or par t i c u la r tra i t s and a r e MLCP D , MLLPD , a nd MLFD . 5 . 2 . 4 S ta t i st i ca l Me t h ods Da ta f or s i ng l e mea su reme n t t r a i ts s uch as greasy f l e e ce we i gh t ( GFW ) , lamb f l e ec e we i gh t ( LFW ) , wean i ng we i ght ( WW ) , p o s t shea r i ng l i ve we i ght ( P S LW ) , CPDAMP , FDAMP , L PDAMP , MLCP D , MLLPD and MLFD we r e a na lysed by ana l ys i s o f va r ia nc e a cc o rd i ng t o t h e f o l l owi ng mod e l : 7 0 Mod e l 5 . 1 whe r: e yi ? k ? = = a n obs e r va t i on o f wo o l o r we i gh t c ha rac t e r i s t i c on t h e mt n s he e p o f s e x k , s e l e c t i o n l i ne 1 , dam age j and b i r t h r ank i ? = an o ve ra l l mea n , b ? = t h e r e g r e s s i on c oe f f i c i en t o f yi ? k ?= on x i ? k ?= whe r e , x i ? k ?m = a n o bs e rved i nd i v id ua l b i r thda t e , r .?. = the f i xe d e f fe c t o f the i t h b i r t hr:ank c la s s d ? = t h e f i xe d e f f e c t o f t h e ? t n age o f dam c la s s J ft.. t k "' +h 0 . 3 0 ) a l though t h e t r e nd was d e creas i ng d i f f e r e nc e s a s t h e lambs became o ld e r . Ram l ambs we re c o n s i s t e n t l y heav i e r ( p < O . O O l ) t han e we l ambs a nd t h e r e l a t i ve adva n tage was not c ons tant ( p < O . O O l ) over t ime . T he d i f f e r e nce b e twe e n ram a nd e we lambs was 2 . 2 ? . 4 7 2 k g a t wea n i ng a nd r o s e ma rked ly over J anuar y, F ebrua r y a nd Ma r c h ( 5 . 2 ? . 6 k g ) , d e c l i ned ove r w i n te r ( 4 . 2 ? . 5 k g ) a nd i nc r eased a ga i n n ear hogge t s hea r i ng ( 5 . 3 ? . 5 kg ) . S e x d i f fe r e nc e s i n g r owth pa t t e r ns can n o t be d i re c t ly a t t r i bu t ed t o s e x i n t h i s s t udy a s ram a nd e we lambs we re g razed s e parat e l y o n d i f f e r e n t b l ocks o f t h e Mas s ey Un i ve r s i ty f a rm . M on t h l y c ha nges i n pa s tu r e qua l i ty a nd qua nt i ty we r e n o t s t a ndar d i zed a c r o s s s e x . 5 . 3 . 1 . 2 S e a s ona l t r e nds a nd l i ne e f f e c ts Ge n er a l l y , l ambs g r ew s tead i ly over January , Feb rua r y and Ma rch . L i t t l e c ha nge ( 0 . 2 - 1 . 6 k g ) i n l i vewe i ght o ccur r e d over w i n t e r . F W l ambs began gr ow i ng aga i n i n J u l y wh i l e C l ambs d i d n o t ga i n s i gn i f i cant we i gh t unt i l Augus t . The r e la t i ve advantage o f FW ove r C l ambs be came s i g n i f i ca n t i n l a t e May a nd c o n t i nued thr oug h t o h ogg e t s hear i ng . T h e r e la t i ve advantage ( FW-C ) /C i s a l s o g i ve n i n Tab l e 5 . 1 . a nd r a nged f r om a mi n i mum o f - 1 . 3 3% i n Janua ry to a max i mum o f 6 . 9 9 % i n Oct o be r . As i n S umne r ' s ( 1 9 6 9 ) data , body we i gh t p la t eaus c o i nc i d e d w i t h pe r i od s o f d e c r eased woo l g r owt h a nd t h e r e t u r n o f p os i t i ve gr owth r a t e s was accompa n i ed by i nc r ea s ed wo o l p r od uc t i o n a s s e e n i n the s ubsequen t d i scuss i on . 5 . 3 . 2 Woo l gr owt h The l e a s t s quar e s means a nd s t a ndard e r r o r s by s e l e c t i on l i ne a nd mon t h f o r CPD , LPD a nd FD a r e p r e se nted , r e s pe c t i ve ly , i n Tab l e s 5 . 2a , b and c a l ong w i t h s i gn i f i ca nce l e ve l s , m i n i mum a nd max i mum va l ue s ( c l e a n woo l gr owt h o n l y ) , a nd t he r e l a t i ve adva ntage o f FW over C a n i ma l s . The s e data f o r CPD , L PD a nd FD a r e a l s o pr e s e nted , r e s pec t i ve ly , i n F i gu r e s 5 . la , b a nd c ( by se l e c t i on l i ne ) a nd F i gur e s 5 . 2a , b a nd c ( by s e l ec t i o n l i ne a nd s e x ) . As w i t h l i vewe i g h t d a ta , s ubc lass means f or f i xed e f f ec t s a r e n o t prese nted b u t w i l l be d i s cuss ed . 7 3 5 . 3 . 2 . 1 F i xed e f f e c ts C l e a n woo l pr oduct i on was s i gn i f i cant l y a f f e cted by date b o r n ( p< O . O O l ) , dam age ( p < O . O l ) a nd s e x o f lamb ( p < O . O O l ) . T he e f f e ct o f date b o r n was n o t c ons i s te nt a c r o ss t i me ( p < O . O O l ) a nd va r i e d i n s i gn w i t h no d i s c e r nab l e t r e nd e xcept a t e ndency t o be n egat i ve . L a t e r b o r n l ambs hav i ng l owe r c le an woo l p r oduc t i o n pe r month t ha n ear l i e r b o r n l ambs . The e f f e c t o f d am age was a l s o i nc o ns i s t e nt a c r o s s t i me ( P < 0 . 0 5 ) w i t h o n l y 3 yea r o ld dams be i ng c ons i s t e n t l y s upe r i or . C l e an woo l p r oduct i on was n o t s i gn i f i ca n t l y a f f e c t ed by b i r t h r a nk ( p > 0 . 5 0 ) . S e x had a ma j o r e f f e c t o n CPD ( p < O . O O l ) a nd was i nc ons i s t e n t acr o s s t i me ( p < O . O O l ) . Ram lambs we r e s upe r i o r t o e we l ambs f r om lamb s h e a r i ng u n t i l Mar c h . R e rank i ngs o f e we s a nd rams we re c ommon ove r w i n t e r w i th ram l ambs bec om i ng c lea r l y s upe r i o r f r om Augus t onwards t o h ogge t s hea r i ng ( F i gure 5 . 2a ) . As ment i oned i n t he p r ev i o us s e c t i on , i t i s d i f f i c u l t t o i n terpr e t s e x e f f e c t s i n th i s da t a due t o t h e graz i ng pract i ce s ad o pt ed as Un i ve r s i ty farm pr o to c o l . F i br e l e ngth gr owt h r a t e ( LP D ) was s i gn i f i cant l y a f f e c t e d by da t e o f b i r t h ( p < O . O O l ) a nd s e x o f lamb ( p < 0 . 0 5 ) . Da t e o f b i r t h e f f e cts we r e c ons i s te n t ly nega t i ve but d i d var y s l i gh t l y ( p< 0 . 0 5 ) a c r o s s t ime wi t h n o c ons i s t ent t r e nd s . S e x e f f e ct s we r e n o t a t a l l c o ns i s tent a c r oss t ime ( p < O . O O l ) a nd va r i ed i n s i gn ( F i gu r e 5 . 2 b ) . The e f f ects o f dam age ( p > 0 . 8 0 ) and b i r t h r a nk ( p > . l O ) wer e not s i gn i f i can t a nd d id n o t va ry wi th t i me . F i br e d i ame ter was s i g n i f i can t l y a f f e c t ed by date o f b i r t h ( p < O . O l ) w i t h l a t e r b o rn l ambs tend i ng t o have f i n e r f i b r es . A l t h o ugh the magn i t ud e o f t h i s t r end was n o t c ons i s t e nt a c r o s s t ime ( p < . O l ) i t was c ons i s tent i n s i gn . F i br e d i amet e r dur i ng t h e year was n o t a f f e c t ed by dam age , b i r th rank o r s e x o f l amb . The e f f e c t o f s e x was not c o ns i s te n t a c r o s s t ime ( p < O . O O l ) wi t h f ema l e s hav i ng grea t e r f i b r e d i ame t e r s t ha n rams o n ly d u r i ng t he pe r i od f r om Apr i l t o Augus t ( F i gure 5 . 2 c ) . Reas ons f o r t h e s e t r e nds by s e x a r e unc l e a r , a s s ta ted prev i ous l y . 5 . 3 . 2 . 2 S e a s o na l pat t e r ns 7 4 Al l t h r e e woo l tra i ts s howed s i gn i f i ca n t s easona l var i a t i on . I n b o t h l i n e s , a nd i n a l l t r a i ts , p r oduc t i o n i nc r ea s ed f r om D ecember t o January, p l a teaued br i e f ly i n February t h e n d ec l i ne d unt i l Apr i l -June a nd i nc r e as e d s t ead i ly a f te rwa rd s . S im i l a r h ogget pat t e r ns ( r anges a nd t i me s o f mi n i mum p r oduc t i on ) f o r Romney s he e p we r e r e po r ted by B i gham e t a l . ( 1 9 7 8? a nd S umne r ( 1 9 7 9 , 1 9 8 3 ) . Abs o l u t e va l ue s o f c le a n woo l p r oduc t i o n , as opposed t o p r od uc t i on p e r a rea o f s k i n , we r e u s e d i n th i s t r i a l becau s e t h e n a ture o f t h e da ta a l l o wed a c c u r a t e pa r t i t i o n i ng o f c l e a n f l e e ce we i gh t . S i nc e t h e same f o l l i c l e s a r e be i ng samp l e d a t e ach c l i pp i ng ( w i th i n a ta t t o oe d pa tc h ) , t he c ompar i s on o f per i od t o p e r i od p r o d uc t i on i s qu i te accur a t e . Whe n t h i s p r oduc t i on was d i v id ed by t he a rea o f the pa t ch , l a r ge d i sc r e panc i e s began t o e me r ge i n t h e data . Many o f t h e s e p r o b l ems a r e poss i b ly r e l a t ed t o the d i f f i c u l t tas k o f accurate ly measur i ng patch a r e a . Measur eme n t o f p e r a r e a o f s k i n p r oduct i on a ls o fa l s e ly e n t r a i ns body gr owt h a nd woo l p r oduc t i on i nt o a n ega t i ve r e la t i o n s h i p . Mos t s tud i e s ( Fe rguso n e t a l . , 1 9 4 9 ; S to ry and R oss , 1 9 6 0 ; S t ua r t e t a l . , 1 9 6 1 ; Ar n o l d e t a l . , 1 9 6 4 ; McFar lane , 1 9 6 5 ; R os s , 1 9 6 5 ; Doney a nd Ead i e , 1 9 6 7 ; W i l l iams and S u i j d e nd o r p , 1 9 6 8 ; H o r t on a nd W i ck ham, 1 97 9 ; Hawk e r e t a l . , 1 9 8 4 , 1 9 8 5 ) o n s eas o na l va r i a t i on i n wo o l gr owt h have bee n conducted o n mat u r e s he e p a nd t he va l ues a nd pa t t e r ns are n o t d i r e c t l y c ompa r a b l e t o hogge t data . Ge ne ra l l y , the seas o na l cyc l e i n F D appea r s t o lag be h i nd that o f L P D a s f ound by S to ry a nd R o s s ( 1 9 6 0 ) , R oss ( 1 9 6 5 ) a nd S umn e r ( 1 9 6 9 ) 7 5 Leas t squa r e s mea ns a nd the i r a s s oc ia ted s ta ndard e r r o r s ( by s e l e c t i on l i ne ) f o r t h e amp l i tude a nd mon t h o f m i n imum p r oduct i on f o r c l e a n woo l gr owt h , l e ng t h a nd f i bre d iame te r a r e s hown i n Tab l e 5 . 3 a l ong w i t h g reasy hogget f l e e ce we i ght ( GFW ) , c l e a n hogge t f le e c e we i ght ( CFW ) , lamb g r easy f l e e c e we i gh t ( LFW ) a nd t he r a t i o o f c l e a n h ogget f l e ec e we i gh t t o P SLW . The amp l i tude o f c l e an woo l gr owth c o r r e s ponds c l os e l y t o Ha r t ' s ( 1 9 5 1 ) e s t ima te o f 8 5% f o r Co r r i ed a l e e we s i n Chr i stchurch . Va l u e s ca l c u lated f r om r ep o r t ed s t ud i e s e l s ewhe r e ( S t o ry a nd Ross , 1 9 6 0 ; Ro s s , 1 9 6 5 ; B i gham e t a l . , 1 9 7 8? range f r om 4 3 % t o 1 1 4 % f or c l ean woo l gr owth i n mat ur e Romney e we s , i nd i ca t i ng t ha t va l ue s ( 8 8 % - 1 1 9 % ) o bta i ne d i n t h i s s tudy a r e we l l w i t h i n r ea l i s t i c l i m i t s . The amp l i tude o f LPD ( 5 2 % - 5 8 % ) c o r r e s ponds we l l t o S t o r y and R oss ( 1 9 6 0 ) a t 4 9 % and R o s s ( 1 9 6 0 ) a t 4 0%- 4 7 % . S im i l a r l y, FDAMP i n t h i s s t udy ( 2 6 %- 2 9 % ) s e ems t o be i n t h e range o f S t o ry a nd Ross ( 1 9 6 0 ) a t 3 8% a nd R o s s ( 1 9 6 5 ) a t 1 5%- 2 4 % . C or r e l a t i o n s amo ngs t s e a s o na l woo l g r owt h va r i a b l e s poo l e d ( whe r e homogen e ous ) acr o s s g eno types are g i ve n i n Tab l e 5 . 4 . C o r r e lat i ons s i gn i f i ca n t ly d i f fe r e n t f r om z e r o a r e ma r k e d w i t h a n a s te r i s k ( w ) . C l e a n f l e e ce we i gh t was h i gh l y c o r r e lated wi t h m i n imum CPD . I n a s imp l e r egress i on a na l ys i s , June CPD a l o n e was a b l e t o e x p l a i n 7 6 % o f t he var i a t i on i n c l e a n f l e e ce we i ght . Th i s i nd i ca t e s tha t s upe r i or i ty f o r c l e a n f l e ec e we i gh t i s h i gh l y r e l a t ed t o w i n t e r woo l produc t i on i n t he s e d a ta . Amp l i tud e var iab l e s we r e nega t i ve l y c or r e la t e d w i t h gr easy and c l e a n f l e ece we ight mea n i ng t ha t s he e p w i t h less s e a s o na l va r ia t i o n i n woo l gr owth mea s ur e s t e nded t o have h i g h e r f l e e c e we i gh t s . The o ppos i te r e la t i o ns h i p was f o und i n t h e Mer i no by Re i s a nd Wi l l i ams ( 1 9 6 5 ) who conc l uded t hat s he e p w i t h phe notyp i ca l l y h i gh f l e e ce we ight s h owed g reat e r va r i a t i on i n s eas ona l wo o l gr owt h . The r e la t i onsh i p be twe e n amp l i t ud e a nd wo o l gr owt h i n t h i s e xpe r ime n t was n o t d e pe nd e n t o n s e l e c t i on l i ne . 5 . 3 . 2 . 3 S e l ec t i o n l i ne e f f e c ts 7 6 As s hown i n Tab l e s 5 . 2 and 5 . 3 , F W s h e e p ma i n ta i ne d h i gh e r ove ra l l s e a s o na l l e ve l s o f p r oduc t i o n , ma i n ta i ne d h i gh e r m i n i mum l e ve ls o f p r oduct i on i n w i n t e r , a nd had s i mi l a r ( FDAMP ) o r r e duc ed ( CP DAMP , LP DAMP ) amp l i t udes o f woo l g r owt h c ha r ac t e r i s t i cs . wot.tld The i nc r e a s ed body gr owt h o f FW s h e e p i n l a t e w i n t e rAn o rma l ly s ugge s t that i ntak e s we r e h i g h e r f o r FW s he e p i n w i n t e r . The p os s i b i l i ty o f i ncreased e f f i c i e ncy o f woo l a nd body g r owt h ca n no t , howeve r , b e d i s r e ga r de d . I n t he s t udy o f Hawk e r a nd Cr o s b i e ( 1 9 8 5 ) , ewe s w i t h a h i s t o r y o f h i gh w i n t e r wo o l g r owth ( W+ ) we re ma i nta i n ed a t h i gh o r l ow f e ed i ng l e ve l s t h e subsequent wi n t e r . W + e we s o u t pe r f o rmed W- e we s a t bo t h f e e d i ng l eve l s , the d i f f e r e nc e s be i ng mor e p r o n ounced u nd e r h i gh f e e d i ng . The s i gn i f i ca nc e o f Hawk e r a nd Cr o s b i e ' s wo r k i s that w i n t e r p roduc t i o n d i f f e r e nces may be d ue mor e t o e f f i c i e ncy t ha n t o i nt a k e . I n t h i s s t udy, a s i n Hawk e r a nd Cr o sb i e ( 1 9 8 5 ) , t h e l a r ge s t p r o p o r t i o na l d i f f e r e nce be t we e n t h e l i nes occur r ed d u r i ng w i n t e r e ve n thoug h t h e l a rge s t a bs o l ut e d i f fe r e nce o ccu r r e d d ur i ng t h e l a s t mon t h pr i or t o hogget shear i ng . S ome a u t h o r s ( Doney a nd Ead i e , 1 9 6 7 ; B i gham e t a l . , 1 9 7 8 ; Hawk e r e t a l . , 1 9 8 4 ) s ugges t that w i t h i n a nd be twe e n br e ed/gr o u p c ompa r i s ons a r e mo r e d i sce r n i ng a t h i ghe r leve l s o f p r oduct i on . The s e r e s u l t s sugg e s t t ha t , d e pe nd i ng on t he pur p o s e o f p e n ? f e d s tud i e s , t h e t ime t o c o nd uc t t r ia ls dea l i ng wi t h me tabo l i c/hormo na l d i f f e r e n c e s b e twe e n l i nes i s i n w i n t e r , whe n p r o po r t i ona t e d i f f e r e nc e s be twe e n groups a r e l a r g e s t . I f FW s h e ep a r e t r u l y l e s s s ea s ona l t han C s he e p , a s t h e d a t a s ugge s t , the n t h ey s h o u l d b e mo re l i k e ly t o r e s p o nd t o 7 7 nutr i t i o na l s t i mu l us d u r i ng t h i s pe r i od . A l though adu l t d i f f e r ences i n l a t e s pr i ng/ear ly s ummer woo l gr owth we r e n o t measur ed i n t h i s t r i a l , the r e l a t i ve c o n t r i but i o n o f t h i s s ect i on o f t h e c u rve s h o u l d be c on s i d e r ed . I n many r e spe c t s , t h e FW l i ne has s i mi lar p r oduc t i ve characte r i s t i c s t o t h e W+ l i n e s o f Hawk e r a nd Cr o s b i e ( 1 9 8 5 ) . I t s h o u l d be i nve s t i ga t e d whe t h e r o r n o t the s eas o na l pa tte r n o f wo o l gr owth can b e r e moved even f u r t he r , i n F W s he e p c ompared t o c , by s upp l e me nta l w i n t e r f e ed i ng . I n a g r e eme nt w i t h o ur f i nd i ngs , D oney ( 1 9 6 4 ) s ugges ted t h a t g ene t i c d i f f e r e nc e s i n me tabo l i c r e s po n s e s to " unspec i f i e d seas o na l f act o r s " m i ght be r emoved by i nt e ns i ve s e l e c t i on f o r woo l g r o wt h . I n c o n t ra s t , Hawk e r e t a l . ( 1 9 8 5 ) c o u l d n o t d e t e ct a d i f f e r e nce i n t h e a nnua l pa t t e r n o f woo l gr o wt h be twe e n s c r e e ne d h i gh a nd l ow f l e e ce we ight l i ne s , a s t h e e n t i r e curve s e emed t o b e l i f t e d i n t h e h i gh f l ee ce we i g h t g r oup . Over t h e c o ur s e o f t h e r e pe a t ed c l i pp i ngs o f t he mi d s i d e s k i n a r e a , i t was n o te d t ha t FW a nd C a n i ma l s had o bs e rva b l e d i f f e r e nces i n t h e c o l our o f s k i n be n e a t h the patch . A l though t h e s e d i f f e r e nces we re d i f f i cu l t t o quant i fy a n e f f o r t was mad e , o n t wo s e parate samp l i ng t imes , t o i d e n t i fy the ge n otype o f e ach s h e e p me r e l y by e xami n i ng s k i n c o l o u r ( no o bv i ous l i ne i d e n t i f i ca t i ons we r e pr e se nt - a l l ocat i o n s t o l i ne we r e c h ec k ed aga i n s t s he e p n umbe r s on t h e data s h e e t s ) . O n b o t h occas i on s , s e l e c t i on l i ne was c or r e ct l y i d e n t i f i ed i n 8 o u t o f 1 0 a n i ma ls . FW s he e p had muc h br i gh t e r s k i n c o l o ur c ha rac te r i s ed b y v i s i b l e p i nk ne s s . C s h e e p had c ha l k y s k i n wi thout p i nk hue s a nd wi th a p reva l e nce o f br own o r gr e y hues . Al t h ough t h e s i gn i f i ca nce o f t h i s o bs e r va t i o n i s unc l ea r , f ur t h e r i nves t i ga t i on i n t o d i f f e r e nces i n s k i n t empe r a t ur e , o r s u r face c i r c u la t i on may be warrante d . G i ve n t he i nc r eas ed r e pr oduct i ve s e a s o n , and e xt e nded pe r i od o f h i gh ovu la t i o n rate i n the W+ e we s o f Montgome ry a nd Hawk e r ( 1 9 8 7 ) , a nd t h e h i gh r e l a t i o ns h i p o f w i n t e r wo o l g r owt h t o h o gge t f l e e ce we i gh t i n t h i s t r i a l , mea s u r e s o f w i n t e r woo l g r owth may ye t pr ove va l ua b l e a s add i t i ona l s e l e c t i o n c r i te r i a i n ram o r e we s e l e c t i on . 7 8 P l ate 5 . 1 Dye -banded s tap l e s i n re l ati on to the mi ds i de patch Tab l e 5 . 1 L e a s t s qua r e s mea ns ( LS M ) , s tandard e r r or s , p e rc entage adva n tage ( ( FW-C ) /C ) * 1 0 0 . a nd s i gn i f i cance o f mon t h l y l i ve we i ght , wea n i ng we i gh t (WW) a nd p o s t s hea r i ng l i ve we i gh t ( P S L W ) by s e l e c t i o n l i ne . M onth C L SM FW L SM s i g . 'ro ( FW-C ) /C = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = ww 2 1 . 8 ? . 4 2 1 . 5 ? . 3 ns - 1 . 3 3 J AN 2 4 . 1 ? . 4 2 4 . 2 ? . 5 n s 0 . 4 1 FEB 2 7 . 2 ? . 3 2 7 . 5 ? . 5 ns 1 . 1 0 MAR 2 9 . 2 ? . 4 2 9 . 9 ? . 5 ns 2 . 4 0 APR 2 9 . 1 ? . 3 2 9 . 8 ? . 4 n s 2 . 4 1 MAY 3 0 . 0 ? . 4 3 0 . 9 ? . 3 * 3 . 0 0 JUN 2 9 . 3 ? . 4 3 1 . 2 ? . 3 * * 6 . 4 8 J UL 3 3 . 3 ? . 3 3 4 . 8 ? . 4 * * 4 . 5 0 AUG 3 3 . 5 ? . 4 3 5 . 8 ? . 4 * * 6 . 8 7 S EP 3 8 . 6 ? . 5 4 1 . 3 ? . 4 * * 6 . 9 9 OCT 4 1 . 3 ? . 5 4 2 . 6 ? . 4 * * 3 . 1 5 P S LW 4 0 . 9 ? . 5 4 3 . 1 ? . 4 * * 5 . 3 8 = = = = = = = = = = = = == = = = = = == = = = = = = = = = = = = = = = = = = = = = = * p < 0 . 0 5 * * p < 0 . 0 1 * * * p < 0 . 0 0 1 8 0 8 1 Tab l e 5 . 2 S e a s o na l woo l g r owth o f C and FW hogge ts : l e a s t s qua r e s means ( LSM ) , s t andard e r r o r s , s i gn i f i ca nce , a nd p e rce ntage advantage ( ( FW-C ) /C ) * 1 0 0 . a . C l e a n woo l gr owt h ( g/day ) ? CONTROL 9o FLEECE WE I GHT ( FW- C ) M o n th L SM M i n Max LSM M i n Max C = = == = = = = = = = == = = = = = = = = = = = = = = == = = = = = = = = = = = = ====== = = == = = = = = = = = = DEC JAN FEB MAR APR MAY J UN JUL AUG S EP OCT 8 . 1 4 ? . 3 7 1 1 . 0 2 ? . 4 8 1 0 . 0 3 ? . 4 0 7 . 6 7 ? . 3 9 6 . 8 8 ? . 3 9 7 . 6 6 ? . 3 5 5 . 9 2 ? . 3 7 6 . 7 7 ? . 3 9 7 . 2 7 ? . 4 6 9 . 2 0 ? . 5 4 1 2 . 4 6 ? . 5 3 4 . 3 9 5 . 8 8 5 . 3 8 4 . 5 8 2 . 9 7 4 . 0 8 2 . 9 2 4 . 1 1 4 . 7 8 4 . 2 5 6 . 6 8 1 3 . 7 5 1 6 . 1 1 1 6 . 8 2 1 2 . 4 0 1 2 . 8 3 1 1 . 1 3 9 . 1 2 1 1 . 9 4 1 1 . 5 7 1 4 . 7 3 2 0 . 2 0 9 . 8 5 ? . 3 2 1 2 . 9 3 ? . 4 2 1 1 . 7 3 ? . 3 5 8 . 9 8 ? . 3 4 8 . 4 3 ? . 3 5 9 . 6 6 ? . 3 1 8 . 5 4 ? . 3 3 1 0 . 4 9 ? . 3 5 1 0 . 4 8 ? . 4 0 1 2 . 9 7 ? . 4 7 1 6 . 9 4 ? . 4 6 5 . 2 2 7 . 0 6 7 . 0 2 5 . 0 7 4 . 6 1 6 . 4 9 4 . 8 0 5 . 8 9 5 . 2 1 7 . 9 3 9 . 1 2 1 5 . 8 8 1 8 . 0 9 1 6 . 8 8 1 3 . 9 8 1 3 . 5 5 1 3 . 7 2 1 3 . 2 0 1 4 . 4 0 1 5 . 2 6 2 3 . 3 3 2 5 . 4 6 2 1 . 0 1 1 7 . 3 3 1 6 . 9 5 1 7 . 0 8 2 2 . 5 3 2 6 . 1 1 4 4 . 2 6 5 4 . 9 5 4 4 . 1 5 4 0 . 9 8 3 5 . 9 6 = = ========== = = = = = = = = = = = = = = ==================== = = = = = == = = = = = = = ? a l l mon t h l y c l e a n woo l g r owth va l ue s a r e s i gn i f i can t ly a f f ected by s e l ec t i on l i ne ( p < . 0 0 1 ) Tab l e 5 . 2 S eas o na l woo l g r owt h o f C a nd FW h ogge ts : l ea s t s q ua r e s means ( LSM ) , standar d e r r or s , s i g n i f i ca nce , a nd pe rcentage adva n tage ( ( FW-C ) /C ) * 1 0 0 . b . L e ng t h p e r day ( mm/day ) Ofo Month C L S M F W L S M s i g . ( FW-C ) /C ======== = = = = = = = = = = = = = = = = = = =============== DEC . 4 7 ? . 0 1 . 5 0 :t . 0 1 * * 7 . 0 7 JAN . 5 1 ? . 0 1 . 5 5 ? . 0 1 * * * 7 . 5 0 FEB . 4 8 ? . 0 1 . 5 3 ? . 0 1 * * * 9 . 5 8 MAR . 4 6 ? . 0 1 . 4 9 ? . 0 1 * 6 . 3 2 APR . 4 5 :t . 0 1 . 4 7 ? . 0 1 * 5 . 6 1 MAY . 4 5 ? . 0 1 . 5 0 ? . 0 1 * * * 1 0 . 7 1 JUN . 3 9 :t . 0 1 . 4 6 ? . 0 1 * * * 1 6 . 7 5 JUL . 4 6 ? . 0 1 . 5 2 ? . 0 1 * * * 1 4 . 4 4 AUG . 4 7 :t . 0 1 . 5 2 :t . 0 1 * * * 1 1 . 9 4 S EP . 5 2 ? . 0 1 . 58 ? . 0 1 * * * 1 1 . 54 OCT . 57 :!: . 0 1 . (;2 ;!: . 0 1 ?7C.IJ( 8 . 010 * p < 0 . 0 5 * * p < 0 . 0 1 * * * p < O . O O l Ta b l e 5 . 2 S e a s o na l wo o l g r o wt h o f C a nd FW hogge ts : l e a s t squa r e s means ( LSM ) , s tandard e r r or s , s i g n i f i cance , a nd pe r c en tage adva ntage ( ( FW-C ) /C ) * 1 0 0 . c . Ave rage f i br e d iame t e r ( }J.m ) ?0 M o n t h c L SM FW L SM s i g . ( FW-C ) /C = == = = = = = = = = = = = = = = = = = = = = = = = = = = = = = ========= DEC 3 0 . 2 ? . 4 3 1 . 0 ? . 4 * 2 . 6 4 J AN 3 3 . 0 ? . 5 3 3 . 7 ? . 4 p < . 1 0 2 . 1 2 FEB 3 3 . 3 ? . 4 3 3 . 9 ? . 4 p < . 1 0 1 . 8 0 MAR 3 1 . 3 ? . 5 3 1 . 5 ? . 4 ns 0 . 6 4 APR 3 0 . 1 ? . 5 3 0 . 7 ? . 4 n s 1 . 9 9 MAY 3 1 . 0 ? . 5 3 2 . 4 ? . 5 * * * 4 . 5 2 JUN 2 9 . 6 ? . 6 3 1 . 8 ? . 5 * * * 7 . 4 3 J UL 3 0 . 1 ? . 5 3 3 . 3 ? . 5 * * * 1 0 . 6 3 AUG 3 0 . 4 ? . 6 3 3 . 2 ? . 5 * * * 9 . 2 1 S EP 3 2 . 6 ? . 6 3 5 . 2 ? . 5 * * * 7 . 9 8 OCT 3 5 . 7 ? . 5 3 8 . 3 ? . 5 * * * 7 . 2 8 = = = = == ============= = = = = = = = = = = = = = = = = = = = 8 2 20 l i _,.--._ 6' 1 5 -o ? 01 '--./ I 1- 5 0 0:::: 0 1 0 _j 0 0 5 z <( w _j u 5 / / / ___ y / / / / --f' , -- --/ / ' , , , I / / / - - - - , -1 - - - - - - - -r - ' / ~ ? ' - - , , , - - -+ - - - - - - - - - / 1? 'l / ' ' ' T " / ? - - - - - - - - I - - - - -- - - 1 ----f/ ? ?--+- ? ----+- / / / / / / / 1 ? LEGEND c ---- --- FW 0 ?---- -T r--- ---- -,---------- - -1------r- ------r----, ---,- DEC84 JAN85 FEB85 MAR85 APR85 MAY85 J UN85 J U L85 AUG85 SEP85 OCT85 F i gure 5 . 1 S e a o na l pa t t e r n o f woo l g r owth i n FW and C h ogge ts . a . S eas ona l va r i a t i o n i n c l ean woo l gr owth ( g/day ) . CO w 20 _...--... 1 8 (/) >. 0 -o CX) N I J ? t _ 1-- ? ? ? I - - 0 ? - 'E 1 6 E '---" ... /' /' J- - - - - - - -I' '/ i3 1 4 1/ , - - - - -L _J t .... .... .... w ' , 0:::: m l.L '1- - ? T_ " - - ? ? 1 - /' - - ? ? - /' ? - -t" ' - - - - - - 1, ""/' --,f---__1'-{_ 1 2 1 0 I I I -- -- I LEGEND ... ... ... ... c ? ... ... f ? ? ?1 ? - - - -- - - FW -1 DEC84 JAN85 FEB85 MAR85 APR85 MAY85 J UN85 J U L85 AUG85 SEP85 OCT85 F i gure 5 . 1 S e a s o na l pa t t e r n o f woo l gr owth i n FW a nd C hogge t s . b . S e a s o na l va r i a t i on i n l e ngth per 2 8 days ( mm ) . CO .p E' :::1_ ? 0:::: w 44 f-w 2 <( 0 w 40 0:::: m L.L w 0 36 <( 0:::: w ? 32 28 24 20 / / / / 1 / ;F- - - - - - -{: .J/ / / / / J" ' / / ? ?? /- - - - ----- - - - - - - - /" / / ./ ?"?,?' ' - - -} - - - - - - - I -- // r / ? ?/ ' <:', 20 -----. 6' 1 5 ""D ? 01 ......._, I I- 5 0 0::: 0 1 0 _j 0 0 5 z <( w _j u 5 0 I I I I I /?--- - / / ? - , I " / ' ' ' , ' / / ' , ' I ' I I I ,- / / / / ' , I / / ' ' , ' I / ,- ,. -- - ' \. / ,- / / -- -..... ' ' ' . , ' ' ' / , , ' /I ,- ,- / ? " ' , , , / / / / / . ? --.-.._ ' . ' ' / / ' ' \ ' , / '? - - - - - / / ,? / ,? / ,- // ,- / ? ' ' ' , , / - - - ? - - - - - ' / / ' - - ? -- - - , ' / ' - - - - - ? ' , _ -/ ,j /,- / -- - - - - '- ' , , / / / / '- ..__ - - - / / ? / -?----- ------ - --- ...... ..__ ./ / / ,, " "?? ? LEGEND C : F -- -- C: M / / ,- . ,./ - - - - - - FW: F - --- FW: M I I ___ _ _ _ T ____ ---?-- -?----- --r ,-- I I DEC84 JAN85 FEB85 MAR85 APR85 MAY85 J U N85 J U L85 AUG85 SEP85 OCT85 F i gure 5 . 2 S e a s o na l pat t e r n o f wo o l gr owth i n FW a nd C ram a nd e we hogge ts . a . S e a s o na l va r i a t i on i n c l e a n wo o l gr owth ( g/day ) . CO C' 20 ? 1 8 (/) >. 0 -o CX) N ? 1 6 ? E E '----' I 1-G z 1 4 w _j w 0::: m LL 1 2 1 0 / / ?? ? ?/ ? ? / ? ? / / / / / _.( #,/ ? / ?/ / ? ? ? J;l7 / / - - ?---?? - - ' ' , ' / ? - - - / ?-::- - _ _ _ _ _ ' ' , ' / ? / - ' ' - - - ' ' ' , "/',, /_ / / / ', / _. , , " / ....._ / , " ... ... ... , " / ?- / - / ' ? - ' - - - ' ' / / / I "' - ? ' - - - - - ' / / - - ? ' ' ' ' - / ' ----- ' ' , ?-- ---- -----/ / - - / ' ' -- ?, / / / I '---' , - - - --- - -?- -- - / , 'Y--?- "' ? -- / / I ??------- - - ?----- "' / , ' ?/ I _ _ FW: F 'v' - - - -LEGEND C : F C : M FW : M - - - -----,- --- --l?--- ------ ---1?-- ------- I I I - ---- ---? DEC84 JAN85 FEB85 MAR85 APR85 MAY85 J U N 85 J U L85 AUG85 SEP85 OCT85 F i gure 5 . 2 Sea s o na l pa tte rn o f wo o l gr owth i n FW a nd C ram a nd e we h ogge ts . b . S e a s ona l var i a t i on i n l e ngth per 2 8 days ( mm ) . CO --.j ? ::::3_ '--._../ 0:::: LJJ 44 f-w 2 <( 0 w 40 0:::: m [L w (.:) 36 <( 0:::: w ? 32 28 24 20 / / ? ? ?/ ? ? ..... .... / / / / / ____ , / // .. / ?==-- - - - - - , '- - - - - - - - - - - - // / / - ---?, '- - - - / / / ?---??::?_ . ? ? - - - - - - - - - - - - - // y :: .- 1 //--:,/ ? _, ..... ..... "-.. .... ... ........ - -- / ../ - / /,/ . "'c :--..-- ? ? ---- ---- - ------ /'7 / ... /' ..... -- .... .... ?---"' / //_..- .........___ .:::-=:::-- .::: - - ------- .,...... ,......... ./. - .... -;;./'/ - ---:_---::..:::.::-- -- -------- -- -/ / - --- - - -- - ---- - ?----------------- - - // ?r ? - - - -- --- - -- -- --- - ------ - - - - - LEGEND ??? -- ------r-- C : F - - -- C : M - ? - - - - - - FW : F - --- FW: M T DEC84 JAN85 FE885 MAR85 APR85 MAY85 J U N 85 J U L85 AUG85 SEP85 OCT85 F i gure 5 .2 S e a s o na l pa t t e r n o f wo o l gr owt h i n FW a nd C ram a nd e we h ogge ts . c . Seas ona l va r i a t i on i n f i b r e d i ame t e r ( Mm ) CO CO 8 9 Ta b l e 5 . 3 Cha racte r i s t i cs o f the s e a s o na l patt e r n o f woo l g r owt h , g reasy f l e e c e we i ght ( GFW ) , c l e a n f l e e c e we ight ( CFW ) , g r e a sy l amb f l e e c e we i ght ( LFW ) a nd ave r age f i br e d i ame t e r ( FD ) i n C and FW s he e p . L east s qua r e s mea n s , s ta ndard e r r or s , a nd per c e ntage adva ntage ( FW? C ) /C ) * 1 0 0 . T ra i t C L S M FW L SM s i g . ( FW?C ) /C = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = CPDAMP ( % ) 1 1 9 . 1 6 ? 6 . 2 7 8 8 . 7 8 ? 5 . 4 9 * * * - 2 5 . 4 8 L PDAMP ( % ) 5 8 . 7 3 ? 2 . 3 7 5 2 . 3 7 ? 2 . 0 9 * - 1 0 . 8 3 F DAMP ( % ) 2 6 . 8 2 ? 0 . 8 8 2 8 . 6 3 ? 0 . 7 7 p < . 1 0 6 . 7 5 MLCPD 4 . 6 2 ? . 4 6 6 . 2 6 ? . 5 6 * * MLLPD 5 . 1 7 ? . 3 9 4 . 8 2 ? . 3 4 n s MLFD 5 . 0 8 ? . 4 7 3 . 6 6 ? . 4 0 * * L FW ( k g ) 0 . 9 8 ? . 0 2 1 . 1 0 ? . 0 2 * * * 1 2 . 2 4 GFW ( kg ) 3 . 6 2 ? . 0 7 4 . 7 8 ? . 0 6 * * * 3 2 . 0 4 CFW ( k g ) 2 . 5 7 ? . 0 6 3 . 4 0 ? . 0 5 * * * 3 2 . 3 3 FD ( ).lm ) 3 1 . 7 4 ? . 2 5 3 3 . 4 0 ? . 2 2 * * * 5 . 2 0 = = = = = = = = = = = = == = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = * p < 0 . 0 5 * * p < 0 . 0 1 * * * p < O . O O l Tab l e 5 . 4 Poo l ed ( w he re ho1ogeneou s 1 or w 1 t h 1 n l i n e I C/FW J c o r r e l at i on s b e t ween wool g r ow t h c h a r ac t er l s t ! c s ( c or r e c t ed for DB, BR, DA and SEX l 1 LCPD LLPD FDAMP CPDAMP LPDAHP H F D SFW C F W S L HLFD MLCPD MLLPD LFD . 631 . 26+ - . 581 - . 581 - . 33+ . 78+ . 371 . 451 . 1 6 - . 1 1 - . 1 7 - . 04 LCPD LLPD FDAMP CPDAHP LP DAMP FD GFW CFW SL HLFD . 57t - . 43 t - . 73+ - . 53+ . 4 7 + . 73t . BO t . 30 t - . 2 1 t - . 1 3 - . 4 t / , 1 - . 09 - . 36t - . 74t . 27+ . 39t . 5 1 t . 59t - . 20+ - , 41/ , 1 - , 51 / . 2 . 63t/ . 8 1 t . 30 1 - . 1 4 - . 06 - . 08 . 09 - . 1 5 - . 08 . 60 t - . 27t - . 2 1 t - . 26+ - . 06 . 09 . 05 - . 05 . 1 1 - . 20t - . 22 t - . 28t - . 23+ . 1 3 . 1 2 . 38 t /- . 1 . 43t . 531 . 30 t - . 1 5 - . ! 9 t . 02 . 94t . 3 1 t - . 1 7 - . 1 '3t - . 0'3 . 44+ - . 1 6 - . 1 5 - . 24r/ , 1 - . 0& - . 07 - . 1 4 / - . 1 7 . 73t/ . 42t . 37 t MLCPD . 37 t 1 * c orrelatiM:> s \jn'? fico.Vlfl_tj d:,fte..-eni. ?rom -zero ( p ?:. O.oi) where_"' LFD m',nim?m month/? .f:tbre diame.t-er- L CPD m?,ni mu m fYlor1fl? c.lea.n woo I ,yow#, L LPD IYf1nirau m moVl 0 !enj'ifl 3rowtl1 MLF'D m o n? o{ m?,Yi?tmum -C; b re d.ic;t.WJ.e:!-e?r M L.CPD mori#! o{ minivnum c /e.a.Vl woo / srow-11, M L L PD m on#? of mini WlLtWl 1 -eVljf/, grow? 5 . 4 C onc l us i ons a nd r e c omme nda t i o ns f o r f u r t h e r s t udy I n t h i s t r i a l , wo o l gr o wt h o f FW sheep was s u pe r i or to C s h e ep d ur i ng the e n t i r e p r od uc t i on pe r i od f r om l amb - t o hogget -shea r i ng . D i f f e r e nc e s wer e mos t p r o n ounced i n the p e r i od s o f l owes t woo l g r o wt h w i th FW sheep p r oduc i ng 5 2 % mor e c l ea n woo l a nd 1 8% mor e c le a n wo o l t ha n C 9 1 h ogge ts i n J u l y a nd F e b r ua ry , r e spec t i ve ly . Re l a t i ve super i or i ty o f FW hogget s f o r F D was , l i k ewi s e , h i ghes t i n J u l y ( 1 0 . 6 3 % ) c ompar e d t o 0 . 6 4% i n Mar ch . Re l a t i ve s upe r i or i ty f or l ength g r o wth rate was h i ghes t ( 1 6 . 7 5% ) i n J une . The c ons i s te ncy o f t h e s e r e s u l ts and the h i gh c o r r e l a t i on b etwe e n measu r e s o f w i n t e r woo l g r owth a nd CFW l ea d t o the c o nc l us i on t hat s ome a s pe c t o f w inter phys i o l ogy has be e n d r ama t i ca l ly a l te red i n r e s po ns e t o s e l e c t i on f o r h ogge t g reasy f le ece we i ght . A r e sp o nse i n w i n t e r p r oduct i on may n o t have be e n f o und i f s e l e c t i o n , i n t h i s o r o t h e r f l oc k s , only was based o n f l e ece we i gh t s wh i ch i nc o r porateA p e r i ods o f s umme r woo l g r owth i n t o the s e l e c t i o n c r i te r i a . S e l e c t i o n o n l a t e r ( De c o r Janua r y ) f l eece we i ghts m ight have pe rmi t ted spr i ng/s umme r va r ia t i on i n woo l gr o wt h t o e xe r t a mor e p r o n ounced i n f l ue n c e o n the se l ec t i on c r i te r i a than w i n t e r woo l g rowth d i d i n t h i s s tudy . The s e l e c t i on o f s h eep o n hogget w i n t e r woo l g r owth ( June , J u l y , Augus t ) may be e f fe c t i ve?a n add i t i ona l c r i te r ia i n i nc r eas i ng h ogg e t a nd l i f e t i me f l eece we i gh t . I f s e l ect i on l i ne d i f f e r e nc e s e x i s t , a s s ugge s ted by C la r k ( 1 9 8 7 ) and McCutcheo n et C\ 1 - ( 1 9 8 7 ) , i n t h e r e qu i r emen t o r me tabo l i sm o f S -c o n ta i n i ng ami no ac ids , the n a l o we r r e qu i r ement o f F W s he e p f or S - conta i n i ng ami n o a c i d s may have e xe r ted a pos i t i ve pe rmi s s ive i n f l ue nce o n w i n t e r wo o l g r owth i n FW she ep . R e i s a nd Wi l l i ams ( 1 9 6 5 ) f ound t ha t t he S -c o n tent f r om h i gh p r oduc i ng s heep fe l l mo r e d ur i ng t i me o f n u t r i t i ona l s t r e s s a s h i g h p r oduce r s ma i nta i ned g r eate r wo o l 92 gr owt h u nd e r t h e s e c o nd i t i ons . S i mi l a r r e s u lts we r e r e po r t e d b y P i pe r a nd D o l l i ng ( 1 9 6 6 ) a nd s howed g reater s easona l va r i a t i on i n S - content o f woo ls f r om f le e ce -we ight s e l e c t e d Me r i nos . A s t udy o f t h e S -conte n t o f month ly f le e c e samp l e s f r om the s e f l oc k s wou ld be o f g r e a t a s s i s ta nce i n u nd e r s ta nd i ng s e a s o na l r e spons e s b e twe e n s e l ect i on l i ne s . S im i lar ly , i t wou ld be o f i n te r e s t t o s ub j e c t s he e p f r om the FW and C l i ne s t o a r t i f i c i a l l y s h o r t p hotope r i ods dur i ng s umme r ( o r t r e a t the a n i ma l s w i t h me l a ton i n ) . A tr i a l o f t h i s na t u r e wou l d he l p t o estab l i s h whe th e r d i f f e r e nc e s i n w i nte r woo l g r owt h a r e due ma i n l y t o a l te r e d photope r i od i c r e sp o ns e , o r t o t he ab i l i ty o f FW s he e p t o ma k e be t t e r me tabo l i c u s e o f l i m i ted f e ed r e s o u r c e s i n w i nte r . I f t h e s t udy was c o nducted a t va r i ous l eve l s o f n utr i t i on , t h e i nte ract i on o f s e a s o na l and n u t r i t i o na l factors c o u l d be e l uc idat ed . Any s t udy o f t h i s na t u r e s h o u l d i nc l ude c ompa r i s ons o f woo l S -conte n t . Th i s s t udy has n o t d e t e rmi ned t h e n a t u r e o f seasona l i n f l ue nc e s o n wi n t e r woo l g rowt h i n the f l e ece we i ght s e l e ct ed l i ne . The s e r e la t i onsh i ps may b ecome c l ear e r a f te r c ompa r i s on o f i nta k e , e f f i c i e nc y o n pas t u r e ( Chapte r 6 ) a nd s eas ona l r e pr od uc t i on ( Chapte r 7 ) . DRY MATTER I NTAKE AND GROS S EFF I C I ENCY OF WOOL AND BODY GROWTH OF FW AND C HOGGETS ON PASTURE ? [ I ntr oduct i on I n comme r c i a l f l ock s , the o b j ect i ve o f f l e ece we i ght s e l ect i on i s t o i mprove the e f f i c i e ncy of woo l p r oduct i on . Th i s e f f i c i ency has b een i ncreased i n Mer i no F + f l ocks i n Austra l i a ( McGu i r k , 1 9 8 0 ) . Ve rcoe a nd Fr i s ch ( 1 9 8 2 ) argued that s h e ep r e pr e s e nt a n i ma l s we l l adapted t o graz i ng ' c ond i t i ons . Furthe rmor e , they s uggest t ha whe n a s he e ps 9 3 usua l env ironment i s d i sr upted , s uch as p lac i ng i t i ndoors f or f e ed i ng o r chang i ng the a n ima l s wi th wh i ch i t s oc i a l i s e s , one o f the r e sponses i s the r emova l o f those c ond i t i ons wh ich s t i mu late f e ed i ng behavi our on pastur e . They suggest that fa i l u res t o demonstrate d i f f e r e nces i n i n tak e , u n l e ss c onducted out o f d o o rs , d o l i t t l e t o impr ove our k n owledge of s heep b i o l ogy, wh i ch is a ba lance be twe e n product i o n potent i a l and product i ve adapt i on t o t he e nv i r onme nt . Whether d i f f e r e nces i n the i ntake o f FW ve r s us C sheep e x i s t on pa s ture rema i ns t o be d e termi ned . I n a ny ca s e , i t i s certa i n l y pr e f e? ab l e t o conduct t h e s e compar i s ons , a s Ve r c oe a nd Fr i sch suggest , under f r e e graz i ng s i t ua t i ons . 6 . 2Mater i a l s and Me thods Expe r i menta l p l an The s t udy was conducted be twe en January and October o f 1 9 8 5 on 1 9 8 4 -bo rn ram hogge ts f r om the FW a nd C l i n e s . The se rams we r e a s ubset o f rams i nvo lved i n the e xpe r i ment descr i bed in C hapte r 5 . I n January o f 1 9 8 5 , 1 5 FW and 1 5 C rams we r e chosen a t random f r om t he i r r e spect i ve l i nes and ha rnes sed for t ota l c o l l ec t i on of faeces over a 1 4 -day 9 4 pe r i od . The dec i s i on was made , a f t e r t h e January c o l l ect i on , t o samp l e 4 ram progeny f r om each o f the f our s i r e s r e pr e s e nted i n each l i ne ( a t ota l o f 3 2 she e p ) wh i le . ma i nta i n i ng as many o f the January samp led rams as poss i b l e . Th i s change wa s t hought t o g i ve a mo re j ud i c i ous samp l i ng o f gene t i c mat e r i a l f r om each o f the l i nes . Whe re a s u r p l us o f s i r e o f f spr i ng had b e en samp l e d i n January they we re randomly de l e ted and e xtra o f f spr i ng , i n other s i re gr oups , we r e added on t h e same rand om bas i s . Thes e 3 2 ram hogge ts we r e ha r nessed r epeated ly f o r t o ta l faeca l c o l l e c t i on dur i ng 2 wee k s i n each o f Apr i l , J u ly a nd Oc t ober o f 1 9 8 5 . Co l l ect i ons we r e dur i ng the m idd l e 2 we e k s o f each 4 wee k wo o l gr owt h pe r i od ( chapt e r 5 ) . Co l l e ct i on months we re chos e n t o c o i nc i d e appr o x i mate l y wi t h s eason , t h e f our c o l l e c t i o ns r epr esent i ng s umme r , autumn , w i nter a nd spr i ng . Pa sture samp l i ng f or her bage a l l owance was comp l e t ed i mmed iate ly pr i o r t o each faeca l c o l l e c t i o n . 6 . 2 . 2 Ha rness and bag des i gn . Ha r nesses a nd bags we r e des i gned , t es ted and bu i l t pr i o r t o the e xper i ment . Ha r nesses a nd bags u s ed are i l l us t rated i n P late 6 . 1 . , be i ng ada pta t i ons o f those r e ported by Ar no ld ( 1 9 6 3 ) and S c o f f i e ld ( 1 9 7 0 ) . A t h i n p l as t i c bag was pegged i ns ide each outer bag s o that faeces c ou ld be ea s i l y r emoved and transpor t ed to t he labora t o ry . Qu i ck r e l ease buck l es fac i l i tated r emova l and r e placement o f the bags a nd the p o l yme r i zed fabr i c o f the outer bags w i ths t o od r epea ted was h i ngs a nd cons ide rab l e a bus e by t h e she ep . Ha r nesses and bags d i d n o t f i t we l l i f rams we r e l i ghter than 2 2 k g . As rams and f l e eces gr ew i t was necessary t o add e xt ens i on straps a l ong the ba ck . ,\ ).' . ? 6 . 4 . 3 Co l le ct i on r out i ne 9 6 One we e k a f t e r we i gh i ng and woo l samp l i ng rams we r e mus te red i nt o temporary ya rds s e t up i n t h e paddock . Har nesses , wi thout c o l l ect i on bags , we r e f i t ted t o each ram ( day 1 ) . On day 2 , at 0 8 : 0 0 h ours , ha r nesses we r e t i ghtened a nd c o l l ect i on bags and l i ne r s we r e put i n p lace . At 0 8 : 0 0 h ours on days 3 a nd 4 faeces we r e c o l l e cted a nd bags we r e checked ca r e f u l ly f o r any s i gns o f faeca l l o s s . Faeces f r om days 3 a nd 4 we r e we i ghed and d i scarded . Days 5 - 1 4 c ons t i tuted the mea s ur ed c o l l ec t i o n pe r i od . Fa eces we r e r emoved and l i ne r s r e p laced each day betwe e n 0 8 : 0 0 a nd 0 9 : 3 0 hour s . Al l bags and ha r nesses we r e r emoved on day 1 4 . Each day dur i ng the c o l l e ct i o n per i od , faeces we r e we i ghed a nd dup l i cate samp l e s ( 1 0 0 - 2 0 0 gms ) we r e we i ghed be f o r e and a f t e r dr y i ng at 1 4 0? F f or 7 2 h o u r s to determi ne dry mat t e r cont e n t . I n s ome c o l l ect i o n pe r i ods l ow dry ma tt e r content o f faeces r e qu i r ed t he dry i ng t ime s t o be e x t ended . 6 . 2 . 4 Pa s t u r e samp l i ng On day 1 o f t he c o l l e ct i on pe r i od 2 0 ra nd om pa tches o f pa s t ure we r e cut t o gr ound l e ve l wi t h i n a 2 5 cm by 7 5 cm fr ame . Grass wa s dr i e d at 1 2 0? F f o r 4 8 hour s and we i ghed t o dete rmi ne the h e rbage a l l owance on pas tu re . Subsample s o f he r bage we r e gr ound i n a hamme r mi l l f i t ted wi t h a f i ne scr e e n . S ubsamp l e s we r e used to de t e rm i ne dry ma tte r d i ge s t i b i l i ty by i n v i t r o d i ge s t i on . 6 . 2 . 5 Wo o l and body g r owth Da ta f r om the exper iment in chapte r 5 we r e me r ged wi t h i nta k e data t o e s t i mate the g r o s s e f f i c i e ncy o f wo o l and body gr owth . E f f i c i ency was measured as t he we i g ht o f wo o l o r body t i s s ue de pos i t ed da i ly d i v i ded by da i ly d r y ma t t e r i ntake o r d i ge s t i b l e d ry matter i n ta k e . 6 . 2 . 6 Stat i s t i ca l me t hods Da ta we re a na l ysed w i t h i n a nd across pe r i ods . The wi t h i n per i od ana lyses o f i ntake i nc l uded i n i t i a l?0?? i ght a t t hat c o l l ect i on pe r i od , as a cova r iate . Un i va r iate a na lys i s o f va r i a nce a t each t i me per i od , as we l l a s r e peated measures ana l yses across the last t h ree c o l l e ct i ons , we r e car r i ed out . 9 7 The mode l i nc l uded t he e f f ects o f i n i t i a l we i ght , b i r t h date , dam age , b i r t h rank , a nd was s im i l a r t o t hose used i n Chapter 5 . The e f f e ct o f body we i ght as a cova r i ate was s i mi lar f or both l i ne s , such that s eparate regr ess i o ns we re n ot r e qu i r ed . 6 . 3 R esu lts and D i scuss i o n 6 . 3 . 1 Measures o f i ntake The rams d i d n ot a ppear t o be bothe r ed by the add i t i on o f ha rness es and bags , a nd r e turned t o norma l graz i ng a f t e r c o l l e c t i on o f fa eces ( P l ate 6 . 2 ) . A lthough s ome faeca l l o sses we re ev ident on the f i r s t or s e cond pr e - co l l e ct i on days , by the t h i rd day a l l bags appeared t o be t i ght and r e lat i ve ly l eak f r e e . The A pr i l c o l l e ct i on pe r i od was qu i t e s ever e l y a f f ected by ryegrass s taggers . S ome rams we re not behavi ng norma l ly a nd faeca l outputs we r e r educed due t o abnorma l gra z i ng . The e f f ect of s tagge rs on d i f f e r ent rams was d i f f i c u l t t o quant i fy and c ou ld n o t be r emoved f r om t h e ana lys i s . Pas ture ava i l ab i l i ty was reas o nab l e i n mos t seas ons , but 9 8 h e rbage a l l owance o f 1 1 0 0 k gDM/ha i n Ju ly may have caused s ome i nges t i on of s o i l wh i ch wou ld b i as upwards t he e s t i mates o f d ry mat t e r i ntak e ( DM I ) a nd b i as d ownwards t h e e s t i ma t e s o f wo o l a nd body gr owth e f f i c i e ncy . Orga n i c ma tter content o f faeca l s amp l e s was n o t pe r f o rmed s o . t ha t d i gestable o rgan i c mat t e r i ntake c ou ld n o t b e e s t i mated . Pas ture a l l owances a nd es t i ma ted d ry mat t e r a nd o r gan i c mat t e r d i ge s t i b i l i t i e s o f the he r bage samp l e s a r e pr e s ented i n Ta b l e 6 . 1 a . Dry mat t e r i ntak e s and d i ge s t i b l e d ry mat t e r i ntak e s ( DDM I ) a r e g i ve n i n ta b l e 6 . l c . No s e l ect i on l i ne d i f fe r ences i n e i th e r DMI o r DDMI we r e d etected i n any s eason . The mean d i ge s t i b le dry ma t t e r i nta kes across l i nes be i ng 0 . 6 7 , 1 . 2 7 , 1 . 8 4 and 1 . 6 5 kg/day i n January , Apr i l , J u ly and Oct obe r , r e spect ive l y . H e rbage a l l owance s a nd dry matt e r d i ge s t t b i l i t i e s o f t he pa st ure at these t ime s we r e 4 5 0 0 , 3 5 0 0 , 1 1 0 0 and 1 9 0 0 k g DM/ha and 6 8 , 7 8 , 7 4 and 7 9 % o n a dry matt e r bas i s . DDM I may have be en b i a s ed downwards i f lambs s e l ected d i e t s o f h i gher d i ge s t i b i l i ty than that o f t h e who l e sward . Repeated measur e s ana lys i s o f i ntakes ove r the l a s t three per i ods a l s o fa i l ed t o i d ent i fy s e l e ct i on l i ne d i f f e r e nce s i n i n ta k e on pas tur e . live Al though s e l e ct i on l i ne d i f f er ences i n i n i t i a lA we i ght we r e s i gn i f i cant i n a l l per i ods ( Tab l e 6 . 1 b ) t he re was n o d i f f e r ence i n the r e l at i onsh i p betwe e n l i vewe i ght and i nt a k e i n the s e l ec ted l i nes . 6 . 3 . 2 E f f i c i e ncy o f l i vewe i ght ga i n The ave rage da i ly ga i ns o f FW a nd C rams dur i ng the c o l l e ct i on months a nd the ca l cu lated e f f i c i e ncy o f those ga i ns , re lat i ve t o d i ge s t i b l e d ry ma tt e r i n ta k e , a r e g i ve n -------------- i n Ta b l e 6 . 2 . Ave rage da i ly ga i n and the c ons equent e f f i c i e nc i e s o f l i vewe i ght ga i n d i d not d i f f e r betwe e n s e l e cted l i ne s i n any o f t he pe r i ods mea sured . 9 9 Wh o l e f l ock d i f f e r e nces i n r ate o f ga i n we r e s i gn i f i cant i n ear ly s pr i ng ( Chapte r 5 ) , but t h e s e l i ne d i f f e r e nces we r e n o t demonstrated i n the subsamp l ed rams . La t e wi nt e r /ear l y s pr i ng d i f f e r ences i n l i vewe i ght ga i n d o not account e nt i r e l y f o r d i f f e r e nce i n hogget l i vewe i ght betwe e n l i ne s , rathe r , ove r the e n t i r e course o f the w i nt e r , t he FW l i ne gradua l ly i nc r e a s e s i t s we i ght advantage over C rams . 6 . 3 . 3 Wo o l gr owth and wo o l gr owth e f f i c i e ncy The c l ean wo o l gr owth ( CWOOL ) a nd the e f f i c i e ncy o f c l e an wo o l gr owth in FW and C l i ne s i s g i ven i n Ta b l e 6 . 2 b . . D i f f e r e nces i n c l e an wo o l gr owth d ur i ng January we r e not s i gn i f i cant in the s ubsamp l ed rams , even though wh o l e f l oc k d i f f e r e n ces i n c l ean wo o l gr owth ove r the same per i od we r e s i gn i f i cant . Dur i ng late s umme r , even wh o l e f l oc k d i f f e r e nces we r e not w ide ly s epa rated ( d i f f e r e nces o f l . 7 g /d ) s o i t i s not s urpr i s i ng that d i f f e r e nc e s o f th i s s i ze we r e not s i gn i f i cant i n the sma l l e r s ubsamp l e . S i m i lar ly , l i ne s d i d not va ry i n the e f f i c i e ncy o f wqo l gr owth i n t h i s f i r s t c o l l ect i o n . Al th ough the d i f f e r e nce i n wo o l g rowth i n s ubsamp l ed rams d ur i ng Apr i l appear ed t o r e f l e c t the d i f f e r e nces f o und i n the wh o l e f l o ck ( C : FW i s 7 . 0 : 8 . 5 g/d i n the wh o l e f l ock ) t he e f f e ct o f rye - grass s tagge r s may have been r e s pons i b l e f o r t h e i nab i l i t y t o d e t ect s i gn i f i cant d i f f e r e nc e s i n the e f f i c i e ncy of wo o l gr owth dur i ng t h i s per i od . D i f f e r e nces appr oached s i gn i f i cance ( p = . 0 8 ) and i t i s u n f o r tunate tha t t h e r.ompar i s o n wa s not unencumbe r ed by e xtrane ous e f f ect s . S e le ct i o n l i ne d i f f e r e nces i n t he e f f i c i e ncy o f wo o l MASSEY UNIVERSIT'r LIBRARY 1 0 0 pr oduct i on dur i ng m id wi n t e r ( Ju l y ) we r e h i gh ly s i gn i f i ca n t a nd the r e lat i ve advantage ( FW-C ) /C o f F W r ams was 6 7 % . The wo o l pr oduct i on o f FW a nd C rams accurate ly r e f l ected e q u i va l ent who l e f l ock compa r i s ons ( C : FW is 7 . 1 : 1 0 . 8 g/d i n the who l e f l ock ) . Th i s l a rge d i f f e r ence i n the e f f i c t e ncy o f w i n t e r wo o l gr owt h i nd i cates that FW sheep a r e not as r e s t r i c ted , by photope r i od i c or nutr i t i ona l va r i ab l e s , as C s he e p ove r wi nt e r . The a b i l i ty o f FW sheep t o r e spond t o add i t i ona l d i e tary p r ote i n ( Chapt e r 4 ) was a l s o eva l ua ted in wi n t e r months . D i f f e r ences i n that expe r iment may have r e f l e cted seas ona l d i f f e r e nces betwe e n geno type s , i n wh i ch exagge rated d i f f e r ences i n e f f i c i e ncy a r e demo?t rated dur i ng w i n t e r months . )s I ncr eased e f f i c i e ncy over wi nte rA r e s pons i b l e , i n the abse nce o f i ntake d i f f e r ence s , f o r susta i ned w inte r wo o l pr oduct i o n i n the FW l i ne . Th i s susta i ned w i n t e r wo o l p r oduct i on may have add i t i o na l be ne f i t s i n the r e s u l tant s tap l e s t r e ngth o f FW and C f l e eces , wh i ch wi l l be eva l uated i n chapte r 8 . Dur i ng Oc tobe r , t he l a rgest abs o l ute d i f fe r e nces i n wo o l pr oduct i on occur betwe e n FW a nd C h oggets . The e f f i c i e ncy of wo o l g r owth dur i ng thl s pe r i od was a l s o h i gh ly s i gni f i cant i n these data . Al t hough the subsampled rams d i d n o t d i sp lay the same magn i t ude o f wo o l g r owth d i f f e r e nces as we r e s e e n i n the wh o l e f l ock ( C : FW is 1 2 . 5 : 1 7 g/day in wh o l e f l ock compa r i s ons ) , d i f f e r e nces i n wo o l gr owth be twe e n C a nd FW subsampled rams we r e a l s o h i gh ly s i gn i f i cant , as we r e t he r e s u l tant e f f i c i e nc i e s . The r e lat i ve advantage o f FW ove r C r ams f o r Oct ober wo o l gr owth e f f i c i e ncy was 3 3% . The r e la t i ve d i f f e r e nces be twe e n l i nes i n wo o l g r owth e f f i c i e ncy, as we l l as the abs o lute e f f i c i e nc i es are we l l wi t h i n the r a nges quo ted i n the l i t e rature ( Bu t l e r and Ma xwe l l , 1 9 8 4 ) . I t i s d i f?f i cu l t t o comment on the t r e nds i n 1 0 1 e f f i c i e ncy f r om 4 - 1 4 months o f age . The h i gh woo l gr owth e f f i c i e ncy o f young an i ma l s i s n o t d i scussed w i d e l y i n the l i te ratur e , and r e lat i ve t o e f f i c i e nc i e s ca l cu lated at la t e r age s , a ppears qu i t e h i gh . I n young a n i ma l s , t h e s k i n r e presents a re lat i ve ly large pr oduct i ve o rga n , such t hat r elat i ve to i nta k e s , s k i n out put of wo o l f i br e r e prese nts a r e lat i ve ly large pr oduct i ve c ompone nt . lhe? resu l ts a r e i n ag reemen t w i t h a number o f Aus t ral ian s t ud i es r e v i ewed ea r l i e r a nd s ummar i zed by Wi l l iams ( 1 9 7 9 , 1 9 8 7 ) . S e l e ct i on f or f l e ece we i ght has r e s u l ted i n s i gn i f i cant i ncreases i n woo l pr oduct i on , i n the p r ese nce o f i ns i gn i f i cant d i f f e r e nces i n measureable f e ed i ntak e , the net r e s u l t be i ng a n i ncrease in the e f f i c i e ncy o f c onve r s i on o f f e ed t o wo o l . 1 0 2 Tab l e 6 . 1 Measures o f pastur e , l i ve we ight and i ntake by s eason and l i ne a ) Pa s ture ava i l ab i l i ty and d i ge s t i b i l i ty Month Pas ture Measur eme nts Ava i l ab l e h e rbage ( k gDM/ha ) Dry ma t t e r d i ge s t i. b i l i ty ( % ) Organ i c matter d i ges t i. b i l i ty ( % ) = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = January 4 5 0 0 6 8 . 2 6 6 . 3 Apr i l 3 5 0 0 7 8 . 3 7 2 . 4 J u ly 1 1 0 0 7 4 . 1 6 8 . 2 Oc t ober 1 9 0 0 7 9 . 2 7 3 . 5 = = = = = = = = = = = = = = == = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = 103 P l ate 6 . 1 Faeca l col l ecti on bags ( wi th l i ne rs ) and h arnesses 104 P l a te 6 . 2 Harnessed rams ret urned to g razi n g 1 0S Tab l e 6 . 1 Measures o f pa s ture , l i vewe ight a nd i n take by seas o n a nd l i ne b ) Month ly i nt i a l 1 i ve we i ght and 1 i vewe i ght ? 7 5 Month I n i t i a 1 wt ( k g ) C FW I n i t i a l wt ? 7 5 ( k g ? 7 5 > C FW = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = January Apr i l J u ly Oc tober 2 9 . 8 ? 1 . 1 2 9 . 0 ? 1 . 3 ns 3 3 . 9 ? 1 . 2 3 4 . 5 ? 1 . 1 ns 3 3 . 4 ? 1 . 4 3 7 . 6 ? 1 . 5 * 4 4 . 9 ? 1 . 3 4 8 . 0 ? 1 . 4 * 1 2 . 7 1 2 . 5 1 4 . 1 1 4 . 2 1 4 . 2 1 5 . 2 1 7 . 3 1 8 . 2 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = 1 0 6 Tab l e 6 . 1 Measures o f pas ture , l i vewe ight and i n take by season and l i ne c ) D i ge s t i b l e dry matt e r i ntake ( DDMI ) and DDMI /wt ? 7 ? Month DDMI ( kg ) c FW DDMI /wt ? 7 5 C FW = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = January Apr i l Ju ly Oc t obe r 0 . 6 5 5 ? . 0 2 2 0 . 6 8 7 ? . 0 2 3 ns 1 . 2 5 7 ? . 1 4 1 1 . 3 1 5 ? . 2 1 8 ns 2 . 0 1 1 ? . 6 2 9 1 . 9 5 5 ? . 3 6 9 ns 1 . 6 2 1 ? . 3 5 8 1 . 7 6 5 ? . 3 3 6 ns 5 1 . 6 5 4 . 9 8 9 . 1 9 2 . 6 1 4 1 . 6 1 2 8 . 6 9 3 . 6 9 6 . 7 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = 1 0 7 Tab l e 6 . 2 Pr oduct i on a nd produc t i ve e f f i c i e ncy by l i ne and season a ) Average da i ly ga i n ( ADG ) and e f f i c i e ncy o f ga i n ADGEFF ca lculat ed r e la t i ve t o DDMI , i n g/kg DDM I . Month ADG ( g/d ) ADGEFF ( g/ kgDDMI ) c FW c FW = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = January 1 2 4 ? 1 0 1 2 8 ? 1 1 1 8 9 ? 2 0 1 8 6 ? 1 5 ns Apr i l 3 4 ? 2 0 6 7 ? 1 5 2 7 ? 1 5 5 1 .? 1 6 ns J u ly 8 9 .? 1 0 8 4 ? 1 1 4 4 ? 6 4 3 ? 5 ns Oc t obe r 1 9 2 ? 1 0 1 8 6 ? 9 1 1 8 .? 7 1 0 5 ? 6 ns = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = b ) C l ean woo l gr owth ( CWOOL ) i n g/d a nd the e f f i c i e ncy o f c l ean wo o l gr owth ( CWOOLEFF ) i n g/k g DDM I Month CWOOL ( g/d ) CWOOLEFF ( g/ k g ) c FW c FW = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = January 1 3 . 0 ? . 6 1 3 . 9 ? . 6 1 9 . 8 ? . 4 2 0 . 2 ? . 5 t1:3 Apr i l 7 . 8 ? . 4 9 . 4 ? . 7 6 . 4 ? . 4 7 . 3 ? . 5 p < . 1 0 J u ly 6 . 8 ? . 4 1 1 . 3 ? . 5 5 . 2 ? . 4 8 . 7 ? . 4 * * * Octobe r 1 3 . 2 ? . 4 1 9 . 0 ? . 4 1 0 . 5 ? . 4 1 4 . 0 ? . 4 * * * = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = 1 0 8 6 . 4 Conc lus i o ns S e l ect i on f or f l e ece we i ght appears to have r e s u l ted i n i mpr oved e f f i c i e ncy . Th i s r e s u l t was cons i s tent ove r a numbe r o f seas ons , a l t hough i t was o n ly s i gn i f i cant i n wi nter , and s pr i ng , i n the se compa r i s ons . I n o t h e r seasons , the fa i l ur e o f the subsampled gr oup t o r e f l e ct changes i n wo o l pr oduct i o n o f the e n t i r e f l ock , o r t he comp l i ca t i ng e f f e cts o f rye -grass s tagge r s on a n i ma l i ntake may have a f fec ted the ab i l i ty to d i s cern d i f f e r e nces i n e f f i c i e ncy . The large r e l at i ve d i f f e r e nces i n e f f i c i e ncy over wi n te r months may i nd i cate a l t e r ed s eas ona l r es ponses i n FW s he ep or may r e f l ect d i f f e r ences i n t h e c ompos i t i on o f wo o l gr own dur i ng t i mes o f nutr i t i ona l s t r es s . Ve rcoe and Fr i s ch ( t qg? descr i be a succe s s f u l a n ima l in t e rms of p otent i a l advantage , d emonstrated du r i ng n o n - s t r e s sed pr oduct i on , and adapt i ve pot e nt i a l that i s r e lated t o the ab i l i ty t o susta i n pr oduct i on du r i n g t i mes o f nutr i t i o na l o r e nv i r o nmental s t r esses . I t wou ld appear that FW s he e p have b oth potent i a l and adapt ive advantages over C s he e p , be i ng able t o pe r f o rm egua l ly we l l d ur i n g the poor w inter and g o od s pr i ng cond i t i o ns . These r e s u l ts a r e i n agreement wi th t h ose o f o ther r e s earchers wi th Mer i nos , summar i zed by W i l l iams ( 1 9 7 9 ) . S e l ect i on f or f l e ece we i ght d oes not appear t o have a l t e r e d t h e i n ta k e o f F W shee p i n t he absence o f d i f f e r e nces i n l i ve we i ght . The e f f i c i ency o f conve r s i on o f f e e d t o wo o l i s i ncr eased , under pas ture and pe n - f ed c ompar i s ons , a s a r es u l t o f se l e ct i on f o r f l e ece we i ght . 1 0 9 I NC I DENCE AND DURAT I ON O F HOGGET OESTRUS 7 . 1 I n t r od uc t i o n a nd r e v i e w of l i t e ra t u r e 7 . 1 . 1 T h e i mpo r tance o f r epr oduc t i ve r a t e t o e f f i c i e nt s he ep pr oduct i on L ow r e pr oduct i ve r a t e i s a ma j or f ac t o r l i m i t i ng t h e p r oduct i v i ty o f s he e p e n t e r pr i s e s . T h e b i o l o g i ca l a nd e c o n omi c e f f i c i e ncy o f s h e e p pr oduct i on wou ld l i k e ly i nc r ea s e w i t h i mp r oved r e p r oduct i ve pe r f o rma nce a s the r e la t i ve ly l a rg e f i xe d c o s t of e we ma i nt a i nance ( Co o p , 1 9 6 1 ) wou ld b e s pr ead ove r a l a r ge r numbe r o f sa l e ab l e o f f s pr i ng ( D i ck e r s o n , 1 9 7 0 ; La r ge , 1 9 7 0 : McGu i r k , 1 9 7 6 ; B i nd o n a nd P i pe r , 1 9 7 6 ; Da l t o n a nd Rae , 1 9 7 8 ; Woo la s t o n a nd But l e r , 1 9 8 7 ) . U l t ima t e ly , l ow r e pr oduct i ve r a t e w i l l r educe t h e r a t e o f g e ne t i c p r og r ess i n a ny cha r ac t e r und e r s e l e ct i on a s l os s o f s e l ec t i on p r e s s u r e r e s u l t s f r om l ow numbe r s o f a va i l a b l e r e p laceme nts . Al t h o ug h s e ve r a l measu r e s o f r e p r oduct i ve r a t e e x i st , t h e numbe r o f lambs wea ne d pe r e we j o i ned pe r yea r ( NLW/EJ ) i s a n i n f o r ma t i ve a s s e s smen t o f t h e annual r e pr oduct i ve pe r f o rma nc e o f t he e we f l oc k . The NLW/EJ i s a c ompo s i te t ra i t r e p r e s e nt i ng f ou r compone nts as f o l l ows : R e p r od uct i ve r a t e wr i t t e n a s = Ewe X Ewe X L i t t e r X Lamb NLW EJ s u r v i va l f e r t i l i ty s i ze s u rv i va l = EPL EJ X EL EPL X NLB X NLW EL NLB whe r e : EPL = e we s p r e s e n t at lamb i ng EL = e we s l amb i ng , a nd NLB = numbe r o f lambs bor n . F u r the rmo r e , l i t t e r s i ze i s a l s o a c ompo s i te t ra i t s ubd i v i d ed a s f o l l ows : L i tt e r s i ze = Ovu la t i on r a t e X Z ygot i c X Emb ryo n i c fe r t i l i ty s ur v i va l wr i t t e n as NLB EL whe r e , i n add i t i on : = OR EL X NFE X NLB OR NFE OR = ovu la t i on r a te , and 1 1 0 NFE = n umbe r o f f e r t i l i s e d e mbryo s . I nc r e a s ed r epr oduct i ve r a t e c a n be a c h i e ved by a l t e r e d manageme nt , d i r e c t man i pu la t i on o r b y t h e j ud i c i ous a pp l i ca t i on o f genet i c p r i nc i p l e s t o any c omb i na t i on o f t h e a bove c omponents o r r e l a t e d phys i o l og i ca l t ra i ts . Ge ne t i c i mp r o veme nt o f r ep r oduct i ve c omponents may not l ead t o i nc r eased r e p r oduct i ve pe r f o r ma nce i n s i tua t i ons whe r e e nv i r onme nta l cons t r a i nt s , na t u r a l s e l ec t i on o r c o ncu r r e nt s e l e c t i on f o r o the r p r oduc t i ve c ha rac t e r s i s a l l owe d t o d i s c r i mi nate aga i ns t i nd i v i dua l s o f h i gh genet i c mer i t f o r r e pr od uct i on ( B i e l ha r z , 1 9 8 6 ; B i e l ha r z a nd Lux f o r d , 1 9 8 7 ) . 7 . 1 . 2 Factors a f f e c t i ng t h e o n s e t a nd durat i on o f o e s t r us i n e we hogge ts Exte n s i ve r e v i ews o f the b r e ed , l i ne a nd e nv i r o nme nta l f act o r s a f fect i ng t he a t ta i nme nt o f pube r ty i n e we l ambs have be e n p r e s ented e l s e wh e r e ( Dyrmundss on , 1 9 7 3 ; 1 9 8 1 ; 1 9 8 3 ; Rat tray, 1 9 7 7 ; Land , 1 9 7 8 b ; L e e s , 1 9 7 9 ; McM i l la n , 1 9 8 1 ) . Only e nv i r onme nta l f ac t o r s w i l l b e br i e f ly s umma r i sed h e r e . D e f i n i t i on o f oube r ty : T h e mos t c ommon pract i ca l d e f i n i t i on o f pube r ty i n e we l ambs i s the f i r s t occur r e nce o f be hav i ora l o e s t r us ( Dyrmundsson , 1 9 7 3 ) . As nume r ous aut h o r s have d emons t ra t ed s ubs equent ly that o e s t r us a nd ovula t i o n a r e n o t a l ways c oncom i tant events i n e we l ambs ( Edey e t a l . , 1 9 7 7 ; 1 9 7 8 ; H a re a nd Bryant , 1 9 8 2 ) , s ome a u t h o r s have pre f e r red t o i nc l ude t he cond i t i on o f p e r mi t t i ng i nsemi nat i on a t a n o vu l a t o ry oes t rus i n t h e d e f i n i t i o n o f pube r ty ( Ed e y e t a l . , 1 9 7 8 ; Q u i r k e , 1 9 8 1 ) . The f o r me r de f i n i t i on w i l l be c on s i d e r ed s a t i s f a c t o ry i n t h i s s t ud y . 7 . 1 . 2 . 1 End oc r i n o l ogy a nd p h o t o pe r i od e f f ects 1 1 1 The e nd oc r i ne events l e ad i ng t o o vu l a t i on i n cyc l i c e wes c a n be s umma r i s e d ( ve r y s imp ly ) a s f o l l ows : 1 . T h e r e l e a s e o f g onad o t r oph i ns ( Lu t e i n i s i ng H o rmone ( LH ) a nd Fo l l i c l e S t i mu la t i ng H o r mo ne ( FS H ) ) f r om t he p i tu i ta r y i s r egu lated by a n e u r o ho rmone ( Gonad o t r oph i n R e leas i ng H o rmon e ( GnRH ) ) f r om t h e hypotha lamus . The s e g o nad o t r o ph i ns s t i mu la t e t h e gr owth o f ova r i a n f o l l i c l e s . 2 . G r owi ng f o l l i c l e s , i n t ur n , syn t h e s ize a range o f s t e r o i d a nd p ept i d e h o rmones , i nc l ud i ng o e s t rad i o l and i nh i b i n , wh i c h e xe r t a n ega t i ve - f e edback a c t i on on t h e r e l ease o f p i t u i ta r y g onado t r oph i ns . P r oges t e r one , produced by t h e c o r pus l ut e um dur i ng t h e l ut ea l p ha s e o f t h e cyc l e , a l s o e xe r ts a n ega t i ve f e edback a c t i on o n the r e l ease o f L H a nd e nhances t he i n h i b i t or y e f f ec t s o f o est rad i o l . 3 . Ve ry h i g h l e ve l s o f o e s t rad i o l , s uc h as are pr oduced by t h e g r ow i ng o var i a n f o l l i c l e n ea r the end o f the cyc l e , a r e a l s o r e s pons i b l e f o r t he pr e - ovulatory s u rge o f L H wh i c h c ons ummat e s t he ovu lat o ry pr ocess by r e l eas i ng t he egg f r om the ma t u r e f o l l i c l e . Th i s pos i t i ve f e e dback o f o e s trad i o l i s f ac i l i t ated by a fa l l i n p r oge s te r one l e ve l s r e s u l t i ng f r om a r e l ea s e o f p r o s tagland i ns f r om t he u t e r us . I n t h e las t d e cade , muc h r e s ea rch has f ocused o n t he e nd oc r i ne c ont r o l o f s eas o na l a n oe s t r us i n sheep a nd t he o ns e t o f pube r ty i n young s he e p . Ova r i a n s t er o i d s e c r e t i on d u r i ng anoes t r us has b e en r e v i ewe d by Karsch e t a l . ( 1 9 8 4 ) who f o und that f o l l i c l e s wh i c h d eve l o p dur i ng anoe s t r us 1 1 2 have a n a ppa r e n t l y n o rma l capa c i ty t o s e c r e t e oe s t rad i o l . Ano e s trus was f ound t o be r e l a t ed t o de c r eased magn i t ude a nd s p i k e f r eque ncy o f e p i s od i c L H s e c r e t i on . They p r o pos ed t ha t dur i ng a n oe s t r us , t h e s e ns i t i v i ty o f the hyp o t ha lamo ? p i tu i ta ry a x i s t o o e s t rad i o l was l owe red . Fos t e r a nd Rya n ( 1 9 7 9a , b ) n o t e d t hat t h e o n s e t o f o e s tr us a t pube r ty a nd t h e occu r r e nce o f o e s t r us a t the beg i nn i ng o f t h e b r e ed i ng s e a s o n o f adu l t e we s m i ght b o t h be r e l a t ed t o a pr o n o unced d e c r ease i n t he r e s po n s e o f t h e hypotha lamus t o t he n e ga t i ve f e edback act i on o f o e s t rad i o l o n subs e qu en t r e l ea s e o f GnRH . They p r oposed t ha t " pube r ty" c o u ld a lmos t be c o ns i d e r ed an a nn ua l pr o c e s s i n the ewe . S i nc e 1 9 7 9 , a p l e t h o r a o f i n f o rma t i o n has b een pub l i s hed a nd r e v i e wed on t h e p hys i o l og i ca l e f f ects o f me l a t o n i n , a n i nd o l e -ami ne r e l eas ed f r om t he p i ne a l g la nd dur i ng da r k ness h o u r s . I t i s t hought t hat me l a t on i n may be t h e chem i ca l r e s pons i b l e f o r t h i s va r ia t i o n i n s e ns i t i v i ty o f t h e hypotha lami c - p i t u i t a ry a x i s t o o e strad i o l , a nd h e nce t he s e a s o na l i ty o f r e p r od uc t i o n a nd pube r ty i n s h e ep ( Fo s t e r a n d Rya n , 1 9 8 1 ; B i ttman e t a l . , 1 9 8 3a ; 1 9 8 3 b ; B i t t ma n and K a r s ch , 1 9 8 4 ; Ka r s c h et a l . , 1 9 8 4 ; Ke nnaway , 1 9 8 4 ; F o s t e r e t a l . , 1 9 8 6 ) . Oth e r s a r e wor k i ng t o dev i s e me t hods wh i c h w i l l a l l ow the t ime o f o ns e t o f o e s t r us a c t i v i ty t o be man i pu l a t ed d i r ec t l y by t h e s trat eg i c t r eatmen t o f e wes ( Ar e ndt e t a l . , 1 9 8 3 ) a nd e we lambs ( Ke n naway a nd G i lmo r e , 1 9 8 4 ; N owak a nd R od way , l 9 8 5 ) w i t h e xogen o us me l a t o n i n . Exoge nous me l a t on i n t r eatme n t , a l though r e qu i r i ng l ong t e rm admi n i s t ra t i on v i a o r a l , s u bcutane ous , r um i na l o r vag i na l r outes , may s t i l l p r ove t o b e a v i a b l e manageme n t o p t i o n d ue t o t he r e l a t i ve ly l ow c o s t o f manufactur i ng syn t h e t i c me l a t on i n . Th i s a r ea o f r e s ea rch wi l l n o t be d i scussed a t l e ng t h ; h oweve r , a f e w po i n t s a r e wo r t h n o t i ng . 1 1 3 i ) Ewe lambs r e qu i r e a n 1 1 - 1 5 we e k pe r i od o f e xpos u r e t o l ong days i n wh i ch t o e s tab l i s h a c i r cad i a n s e ns i t i v i ty t o me l a t o n i n ( Ye l l on a nd Fos te r , 1 9 8 2 ; 1 9 8 5 ) . W i t h ou t t h i s l ong -day e xp os u r e pube r ty i s d e l ayed . I n b r e eds w i t h p r o n ounc ed s eas o na l i ty , pube r ty may b e d e layed u nt i l t h e f o l l ow i ng autumn/wi n t e r as i s t h e c a s e i n lambs b or n a nd r ea r ed o u t o f s e a s o n ( Ke nnaway , 1 9 8 4 ) . i i ) The t r an s i t i on i nt o adu l tho od i s n o t s udde n but , r a t he r , i s c ha rac t e r i s ed by s h o r t e ne d o r i ncomp l e t e cyc l e s d u r i ng wh i ch pa r t o f t h e e nd oc r i ne system b eco me s " pr i me d " t o t h e pr e s e nce a nd a c t i o n o f pr oge s t e r o ne ( Fo s t e r e t a l . 1 9 8 4 ) . One o r mor e o f t hese cyc l e s may i nvo lve s i l e n t ovula t i o ns ( Fo o te e t a l . , 1 9 7 0 ; F o s t e r a nd Rya n , 1 9 7 9Q?Har e and Brya nt , 1 9 8 2 ) . T h e f i r s t o vu l a t o ry o e s t r us occu r s s ubs equent t o the s e i r r e gu l a r 11 cyc l e s . S im i l a r " trans i t i ona l cyc l e s a r e o f t e n s e e n i n a d u l t e we s ( Ka r sc h e t a l . , 1 9 8 4 ) . i i i ) Ewe h ogget l i ve we i gh t , gr owt h r a t e , and age i nt e ra c t w i t h t h e a bove dynami c s ys te m such that t h e e xp o su r e o f t h e young e we t o t h e appr opr i a t e phot o pe r i od i c s t i mu l i d oe s n o t nece s sa r i ly gua rante e that the lamb w i l l a t ta i n pube r t y . The s e i nt e r ac t i ons may be d epe nd e n t o n g e ne t i c fac t o r s ( Ra t t ray , 1 9 7 7 ; L and , 1 9 7 8 b ) . i v ) Ce s sa t i on o f o e s t r us a c t i v i ty i n b o th ewes a nd e we l ambs s e ems t o be a r e s u l t o f r e f racto r i ne s s o f t he hyp o t ha lami c - p i t u i ta ry a x i s t o the e f f e cts o f me l a t o n i n . 1 1 4 7 . 1 . 2 . 2 Age and l i ve we i ght Ca r e mus t be ta k e n i n ge n e r a l i s i ng a b o ut t he mi n i mum age o r l i vewe ight r equ i r ed f o r the a t ta i nme n t o f pube r ty a s age , b i r t h rank , s e a s o n o f b i r t h , gr owt h r a t e and g ene t i c e f f e c ts c an a l l i n te rac t wi t h pho t o pe r i od i c c o nd i t i o n s . S e ve r a l N ew Z e a land s t ud i e s have s h own that a n i ma l s r e ach i ng pube r ty i n the f i r s t aut umn/w i n t e r t e nd t o be h eav i e r t h an t h o s e wh i ch d o n o t ( Ch ' a ng a nd Ra e s i d e , 1 9 5 7 ; H i ght e t a l . , 1 9 7 3 ; Meye r a nd F r e nc h , 1 9 7 9 ; Bak e r e t a l . , 1 9 8 1 ; McM i l la n a nd McDona l d , 1 9 8 3 ; As o f i , 1 9 8 4 ) . I n o t h e r s t ud i e s l i t t l e o r n o d i f f e r e nce was f o und ( Ba k e r e t a l . , 1 9 7 9 ; Qu i r k e , 1 9 7 9 ) . An i ma ls b o r n l a t e r i n t h e s e a s o n w i l l t e nd t o r e a ch pube r t y a t a younge r age a nd l owe r l i vewe i ght than those bor n e a r l i e r i n t h e yea r a s c r i t i ca l p h o t ope r i od i c e f f ects a r e e xpe r i e nced b y e a r ly- a nd l a t e - b o r n lambs at s i m i la r t i me s o f t h e yea r ( Hu l e t e t a l . , 1 9 6 9 ; Dyrmund s s o n , 1 9 7 3 ; 1 9 8 1 ; 1 9 8 3 ; D i c k e r s o n a nd Las t e r , 1 9 7 5 ; Ced i l l a e t a l . , 1 9 7 7 ; Bak e r e t a l . , 1 9 7 9 ; Qu i r k e , 1 9 8 1 ) . Ear ly-bo rn ewe s , p e r haps due t o a l i ve we i ght adva n tage , r each pube r ty ea r l i e r tha n l a t e - b o r n ewe s ( Dyrmund s s o n a nd L e e s , 1 9 7 2a ) . Twi n bor n lambs a r e o f t e n o ld e r a nd l i ght e r a t f i r s t o e s t r us , pa r t i c u l a r l y i f l a t e b o r n , due t o the c omb i ne d e f f e c t s o f l owe r body we i gh t a nd / o r body we i ght ga i n ( H u l e t e t a l . , 1 9 6 9 ; Ba k e r e t a l . , 1 9 7 8 ; Dyrmundss on a nd L e e s , ( 1 9 7 2a ) . 7 . 1 . 2 . 3 P r e s e nce o f t h e r am Al though s udden i nt r od uct i o n o f rams i n t o gr oups o f pr e pu be r ta l ewe s can l ead t o o e s t r us synchr on i za t i on , t h e date o f f i r s t o e s t r us i s usua l l y una l te r ed ( Dyrmunds s o n a nd L e e s , 1 9 7 2 b ) . 1 1 5 7 . 1 . 3 S e l e c t i o n f o r i mpr oved r epr od uc t i ve pe r f o rma nce 7 . 1 . 3 . 1 D i r e ct s e l e c t i on Ea r ly r e v i e ws o f ge ne t i c i n f l ue n c e s o n r e p r oduc t i on i n s h e e p we r e qu i te pess imi s t i c ( Re e ve a nd Robe r t s o n , 1 9 5 3 ) a nd , a l t hough b r e ed d i f f e r ence s we r e r e c ogn i s ed , i nd i v i d ua l va r i a t i on was c ons i d e r ed i nc o n s e qu e n t i a l . La t e r wo r k s ho we d t ha t d i r ec t s e l e c t i on f or i nc r e a s ed f e r t i l i ty wou ld l i k e l y y i e ld o n l y l i mi ted i mpr oveme n t , p r i ma r i ly becau s e t he max i mum l e ve l o f p e r f o rma n c e i s 1 0 0% , but a l s o b ecause h e r i tab i l i ty a nd r e pe a ta b i l i ty va l ues f o r fe r t i l i ty we r e v e r y l ow ( Young e t a l . , 1 9 6 3 ; Tur ne r , 1 9 6 9 ; McGu i r k , 1 9 7 6 ; Land , 1 9 7 7 ; 1 9 7 8a ) . The o t he r , pe r haps mo r e i mp o r t a n t i n f e r e nce , was t ha t f e cu nd i ty s howed s u f f i c i e n t g e ne t i c va r i a t i o n , a nd r e pea tab i l i ty , t o wa r rant d i r ec t s e l ec t i o n . G e ne t i c d i f f e r e nc e s i n f e c u nd i ty b etwe e n a nd w i t h i n mos t b r e e ds o f s h e ep a r e c o n s i d e r ed t o be due t o many g e n e s o f s ma l l e f f e c t . S e l ec t i on f o r i nc r e a s ed f e cund i ty i s a s s umed t o p r oduce s ma l l i nc r eme nta l changes i n a phe n o typ i ca l ly d i s c r e t e characte r . The e xc e pt i on t o t h i s i s t h e B o o r o o l a Me r i n o whe r e a s i ng l e gene , t h e F-ge ne , o f ma j o r add i t i ve e f f e ct i s r es pon s i b l e f o r muc h o f t he obs e r ved va r i at i on i n o vu l a t i o n r a te i n t h i s popu la t i on ( P i pe r a nd B i nd o n , 1 9 8 2 ) . R e c en t wor k o n t he mecha n i cs o f o va r ian f o l l i c u la r d e ve l o pme n t ( Dr i a ncou r t e t a l . , 1 9 8 6 ; D r i a ncour t a nd F ry , 1 9 8 8 ) has s hown that s e l e c t i on f o r h i gh ovu lat i o n rate i n B o o r o o la s , F i nns a nd Roma novs has l ed t o t h ree d i s t i nc t o v u l a t or y mechan i sms , each o f wh i ch he lps t o c ont r o l t he f i na l obs e r ved ovu la t i o n r a t e . As our unde r s tand i ng o f ovu l a t i on r a t e i nc r e a s e s i t may be poss i b l e t o s e l e c t d i re c t l y f o r und e r l y i ng h o rmo na l a nd phys i o l og i ca l t ra i t s . A number o f f e r t i l i ty/ f e cund i ty s e l ect i o n f l oc k s we r e i nd e pe nd en t l y e s ta b l i s hed i n N ew Zea land ( Wa l lace , 1 9 5 8 ; 1 9 6 4 ; C l ar k e , 1 9 7 2 ; 1 9 7 7 ) a nd Aus t ra l i a ( Tu rner 1 9 6 2 ; 1 9 6 9 ; 1 1 6 Y o ung , e t a l . 1 9 6 3 ; McGu i r k , 1 9 7 6 ) . The c entra l l im i tat i o ns o f t h e s e sys t ems we r e s o o n po i nt e d o u t , name l y : i ) c ha rac te r s we r e s e x - l i mi te d a nd rams had t o be s e l e c t ed o n t h e bas i s o f t h e pe r f o rma nce o f f e ma l e r e l at i ve s , i i ) a ge o f the e we e x e r ted c o ns i d e r a b l e i n f lue nc e o n the l eve l of p e r f orma nce a nd h e r i ta b i l i t y , i i i ) t h e r am ' s c o nt r i but i on t o c o ncept i o n rate o f te n mas k e d i mpor tant va r i a t i on i n e we t r a i t s , a nd i v ) f e r t i l i ty a nd f ecund i ty we r e t he ms e lves i n f l ue nced by t h e e we l amb ' s b i r t h s ta t us . Eve n g i ve n t he s e c omp l i ca t i ons , a nn ua l g e ne t i c ga i ns o f 1 - 2 l ambs d ocked p e r 1 0 0 ewe s j o i ne d have b e e n a c h i e ved i n t h r e e s e pa rate s e l e c t i o n e xpe r i me nt s Eas t o e , 1 9 7 0 ; Cl a r k e , 1 9 7 2 ) . 7 . 1 . 3 . 2 I nd i r e c t s e l e c t i o n ( Tu r ne r , 1 9 6 8 ; Dun a nd The d i f f i cu l t i e s i nh e r e nt i n i mpr ov i ng r e pr oduct i ve r a te by d i r e c t s e l e c t i o n have pr ompted many s t ud i e s i n t o me thods o f i nd i r ec t s e l e ct i o n o r s e l ec t i on f o r c omponent t r a i ts , e s pe c i a l ly mea s u r e s o f fe r t i l i ty/ f ecund i ty e v id e nt a t a n e a r l i e r age , i n a n a t t empt t o o bv i a t e t he p r ob l ems out l i ned a bove . P o t e n t i a l s e l ec t i o n c r i te r i a have b een r e v i ewed by B i nd on a nd P i pe r ( 1 9 7 6 ) , Land ( 1 9 7 7 ) , B r ad ford ( 1 9 8 5 ) , Pur v i s ( 1 9 8 7 ) a nd ( i n Romneys ) i nc l ud e : Da l t on a nd Ra e ( 1 9 7 8 ) , a nd i ) p lasma L H a nd FSH l e ve l s , i i ) t e s t i s g r owth a nd d i ame te r , i i i ) ovu lat i o n r a t e , i v ) numbe r o f h o gget o e s t r us e s , a nd V ) l i vewe i ght at wea n i ng or 1 4 - mo n t hs . 1 1 7 F S H a nd L H have the adva n tage o f be i ng measu ra b l e i n b o th s e xe s a t a n ear ly age ; h owe ve r , t he pu l sat i l e na t u r e o f L H r e l ease mea ns t hat o ne b l o od sample i s un l i k e l y t o b e a r e l i ab l e i nd i ca t o r o f L H s t a t us . Measureme n t o f F S H c o nc e nt ra t i on pe rm i t s d i s c r i m i na t i o n betwe e n ewe l ambs o f va r y i ng mer i t f o r f e r t i l i ty/ f ec und i ty but n o t be t we e n ram lambs ( B i nd o n a nd P i pe r , 1 9 7 6 ; R i c o rdeau e t a l . 1 9 8 4 ) . Exce l l e n t d i s cus s i on s o f F S H a nd LH l eve l s a nd t he i r i nte r act i o ns wi t h gene t i c a nd e nv i r onme nta l fac t o r s can be f ound i n F i nd lay and B i nd o n ( 1 9 7 6 ) , Land ( 1 9 7 8 b ) a nd L a nd a nd Car r ( 1 9 7 9 ) . I n s e a rch o f a c ha r a c t e r i n rams wh i ch may be r e l a t ed t o c omponent o f f ema l e r e p r od uc t i on , Land ( 1 9 7 3 ) a nd I s lam a nd L and ( 1 9 7 7 ) s t ud i ed t e s t i s gr owth rate a nd d i ame t e r i n b r e eds a nd c r os s e s d i f f e r i ng i n f ecund i ty . Th i s wo r k , a nd p r e l imi na ry r e s u l ts f r om a d i ve rgent l a rge ve r s us sma l l t e s t i s d i ame te r s e l e c t i o n t r ia l , a r e s umma r i s ed by Land ( 1 9 7 8 b ) . An i nc r ea s e i n a d u l t t es t i s d i amet e r was accompan i e d by a d e l ayed e nd t o the breed i ng s e a s o n a nd h i ghe r ovu la t i on r a t e i n t he large t e s t i s l i ne . I nc reased j uve n i l e t e s t i s d iame te r , a nd e a r ly tes t i s gr owt h r a te , we r e a s s oc iated w i t h i nc r ea s ed o vu la t i on rate a nd e a r l i e r o ns e t o f t h e b r eed i ng s e as on . The he r i tab i l i ty o f t e s t i s d i ame t e r i n s h eep has r a nged f r om 0 . 1 t o 0 . 6 a nd a d j u s tme n t f o r d a t e o f b i r t h a nd b i r t h r a n k a r e r equ i red ( K i l gour e t a l . , 1 9 8 5 ; P u rv i s , 1 9 8 7 ) . The pr ospect o f u t i l i s i ng ovu la t i o n rate ( measured by e ndoscopy ) as a s e l ec t i on c r i te r i on has r ecen t l y r e c e i ve d mor e a t t ent i on ( B rad f o rd , 1 9 7 2 ; H i ght e t a l . , 1 9 7 3 ; Han raha n , 1 9 7 4 ; B i nd o n a nd P i per , 1 9 7 6 ) . Ovu la t i on r a t e i s h i g h ly r epeatable b o t h wi t h i n ( . 6 9 ) a nd be tween ( . 1 5 t o . 7 8 ) yea r s ( Tur ner , 1 9 6 2 ; Han raha n , 1 9 7 6 ) . The h i gh e s t e s t i mat e s o f r e peata b i l i ty we r e o bta i ned i n h i gh f ecund i ty b r eeds such as the F i nn i s h Landrace . The her i tab i l i ty o f ovu la t i on r a t e ha s n o t be e n r e l i a b l y assessed . A lthough t h e 1 1 8 r e l a t i o n s h i p betwe e n ovu la t i o n r a te and l i t ter s i z e i s l e s s t ha n un i ty ( Ha n raha n , 1 9 7 6 ) i t a ppear s s a f e t o c onc l ude t ha t l i t t e r s i ze w i l l i ncrease f o l l ow i ng se l e c t i o n f o r ovu la t i on r a t e . Sm i t h e t a l . ( 1 9 8 7 ) have demons t ra t ed a c l os e gene t i c r e l a t i o ns h i p be twe e n na tur a l l y occur r i ng ovu l a t i on r a t e s a nd t h o s e i nduced by P r egnant Ma r e S e r um G o nad o t r o ph i n ( PMSG ) . Treatme nt wi t h PMSG had the adva n ta ge o f a l l ow i ng o vu la t i on r a te t o be e xpressed i n a pr o p or t i on o f o t h e rw i s e a novu la r p repube r ta l e we lambs . A prac t i ca l pr ogramme f or t h e u se o f ovu la t i on r a t e t o impr ove f e cund i ty i s o u t l i ned by Hu l l a nd Ha nn i ng ( 1 9 8 0 ) . L i k e ovu la t i on r a t e o r f e r t i l i ty , t h e number o f t ime s a e we o r e we h ogge t d i s p lays oes t r u s i s a mea s ure o f o va r i a n a c t i v i ty . H e r i ta b i l i ty e s t imat e s f or t h e numbe r o f h ogge t o e s t r us e s i n New Z e a l a nd Romneys , s umma r i s ed by Da l t o n a nd Rae ( 1 9 7 8 ) , a r e h i gh e r than t h o s e o f o t h e r r epr od uc t i ve t ra i ts measured i n ma ture ewe s . The n umber o f h ogge t o e s t r us e s has a l s o b e en pos i t i ve ly r e l a t ed to s ubseque n t r e product i ve r a t e i n a number o f w i t h i n ( Ch ' a ng a nd Rae , 1 9 7 0 ; 1 9 7 2 ; B i nd o n a nd P i per , 1 9 7 6 ) , a nd betwe e n b r eed s t ud i e s ( Dyrmund s s o n , 1 9 7 3 ) . T h e perce ntage o f ewe hogge t s d i s p lay i ng o e s t r us i s a no ther way o f descr i b i ng o e s t r us occurre nce i n h ogge ts . H i g her s ubsequent r eproduc t i ve pe r f orma nce i n e wes a b l e t o s how o e s t r us i n the i r f i r s t a u t umn has be e n w ide ly demonst rated ( Hu l e t e t a l . , 1 9 6 9 ; H i gh t and J u ry , 1 9 7 6 ; Ba k e r e t a l . 1 9 8 7 ) . A r e c ent r e v i ew o f t he ge ne t i c a nd phys i o l og i ca l r e l a t i o ns h i ps betwe e n gr owth a nd r e pr oduct i on i n mamma l s c o nc l uded t ha t mature a nd yea r l i ng l i vewe i ght had s t r o ng g ene t i c c or r e l a t i ons ( . 4 4 t o . 7 8 ) w i t h the number o f l ambs b o r n pe r ewe ma ted or per ewe lamb i ng ( Br i e n , 1 9 8 6 ) . G ene t i c c or r e l a t i ons w i t h wea n i ng we i ght we re a l s o p o s i t i ve but o f l e s s e r magn i tude ( . 1 7 t o . 3 7 ) . Ba r l ow a nd Hedge s ( 1 9 7 6 ) s howed s i mi lar e we l amb r e pr oduct i ve pe r f orma nce i n l i ne s s imu l ta ne o us ly se l ect ed f o r r e pr oduct i ve rate , wea n i ng 1 1 9 we i ght a nd c l e a n f l e e c e we i ght o r s e l ec ted o n wea n i ng we i ght a l one . Re cent wor k by Dav i s ( 1 9 8 7 ) , i n Me r i n os , demons tra ted c o r r e l a ted r e sponses to s e l e c t i o n f o r i nc reased wea n i ng we i ght i n a l l r e product i ve t r a i t s e xcept f e r t i l i ty a nd pr o l i f i cacy . The c o r r e l a t ed r e sponse r e s u l ted f r om i nc r eased lamb sur v i va l a nd r ear i ng a b i l i ty o f the dams . Compa r i s ons o f Rua k ura l i ne s d i f f e r i ng i n r e pr oduct i ve r a t e have n o t a lways demonst r ated d i f f e r e nces i n wea n i ng we ight wh i l e 1 4 -month we i gh t was usua l ly h i ghe r i n the h i ghe r f e c und i ty l i ne s ( C l ar ke , 1 9 7 2 ; Da l t on and Rae , 1 9 7 8 ; Ba k e r e t a l . , 1 9 8 7 ) . 7 . 1 . 4 R e l a t i on s h i ps be t ween wo o l gr owth and r epr oduct i on Es t imat e s o f t he ge ne t i c c o r r e la t i o n b etwe e n h ogge t greasy f l eece we i gh t and s ubs equent l amb pr oduc t i on have va r i ed f r om s t r o ng ly nega t i ve ( - . 8 5 ) t o s t r o ng ly pos i t i ve ( + . 9 2 ) i n s t ud i e s by K e nnedy ( 1 9 6 7 ) , B l a i r ( 1 9 8 1 ) a nd Dav i s and K i ngho r n ( 1 9 8 6 ) . Es t imat e s pub l i shed p r i o r to 1 9 7 8 ( mo s t o f t hem n ega t i ve ) have b e e n r e v i ewed by L ewer ( 1 9 7 8 ) . L ewe r ' s own e s t imates o f t he ge ne t i c c o r re lat i on b e twe e n numbe r o f lambs weaned and h o gge t greasy f leecewe i gh t we r e negat i ve but va r i ab l e , a nd ranged f r om - . 5 4 t o - . 0 4 . N one o f the genet i c c o r r e l a t i on s was s i gn i f i cant ly d i f f e r e n t f r om ze r o . Turner ( 1 9 7 2 ) c o nc l ud e d that ava i la b l e e s t imat e s o f t h i s gene t i c c o r r e l a t i on we r e n o t s u f f i c i e n t l y antago n i s t i c t o p reve n t s imu l ta ne o us s e l e c t i on f o r woo l , mea t a nd r e p r oduct i on . O n t h e bas i s o f Mer i no parame t e r s , j ud i c i ous c r oss -breed i ng may be a be t t e r me thod to i mpr ove a l l t h r ee t r a i ts a s qu i c k l y a s poss i b le ( Turne r , 1 9 7 2 ) . S he a ls o c omme nted on t he h i g h l y va r i ab l e repor ted gene t i c c o r r e la t i ons b etwe e n f l eecewe i ght and r e pr oduct i on a nd n oted tha t fa i l u r e t o account f u l ly f o r b i r t h r ank e f f ects may b i as t h i s c o r r e la t i on downwards . 1 2 0 An a s s oc i a t i o n be tween the s e a s o na l i ty o f wo o l g r owt h and l e ng t h o f t he r epr oduc t i ve s e a s o n was f ound by Montgome r y ( 1 9 8 7 ) a nd Mon tgomery a nd Hawk e r ( 1 9 8 7 ) . The s e a u tho rs d emo n s t r a ted h i gher ovu la t i o n r a tes a nd a pr o l o nged b re e d i ng s eason i n Romn ey a nd P e r e nda l e e wes wi t h a h i s t o ry o f h i g h , r a t h e r t han l ow , w i n t e r wo o l gr owth . They a l s o c omme nt ed o n t he re levance o f t he i r r e s u l t s t o a c r o s s b r e ed c ompa r i s ons o f t h e sea s o na l i ty o f wo o l gr owth a nd r e pr oduc t i on . Hea th a nd Lynch ( 1 9 8 2 ) demonstra ted a na lo go u s i nt r a -spec i f i c d i f f ere nce s i n s e ns i t i v i ty o f ha i r gr owth a nd r e p roduc t i o n t o exoge n o us me l a t o n i n i n s t ra i ns o f wh i te f o o t ed m ice f r om northe r n a nd s ou t he r n r e g i ons o f t he Un i te d S ta t e s . I t rema i ns t o be s hown whe t h e r breed d i f f e r e nc e s i n t h e s e ns i t i v i ty o f phys i o l og i ca l systems t o pho t ope r i od r e l a t e t o d i f f e r ences i n t he l e ve l o r pa tte rn o f p roduc t i on o f me l a t o n i n , or t he r e s ponse o f e n d oc r i ne or t arget t i s s ues t o c i rcu lat i ng me l a t o n i n c o ncent rat i o n . S e l e c t i on f or h i gh hogg e t g reasy f l e ece we i ght i n t he Mas s ey Un i ve r s i ty PT Romney f l oc k h a s b ee n accompa n i e d by c o r r e l a t ed r e s ponses i n wea n i ng we i gh t , h ogge t l i vewe i g h t a nd t he number o f lambs b o r n a nd r e a r ed pe r ewe l i f e t ime ( B 1a i r , 1 9 8 1 ; B l a i r e t a l . , 1 9 8 4 ) . The pathways t h r ough wh i c h s e l e c t i o n f o r i nc r eased f l e e cewe i gh t has l e d t o i nc r eased l amb product i on i n t h i s f l oc k have n o t ye t be e n e l uc i dated . P re l im i na r y a na lys e s o f 1 9 8 2 - , 1 9 8 3 - a nd 1 9 8 4 - b o r n t wo - t o o t h lamb i ng r e c ords have f a i l e d t o s h ow s i g n i f i ca n t d i f f erences i n e i t he r f e r t i l i ty ( EL/EPL ) o r f e c und i ty ( LB/EL ) . Th i s i mp l i e s t h a t d i f f e rences i n l i f e t i me r e pr oduct i ve pe r f o rma nce a r e due to lamb i ng pe r f o rmance a t l ater l amb i ngs . Tur n e r ( 1 9 6 9 ) has s hown t h a t d i f f e r e nces i n lamb product i on we r e o f t en n o t e v i d e n t u n t i l t h e s e c o nd o r l a ter lamb i ngs . 1 2 1 I ncr eased r e p r o d uc t i ve pe r f o rma nce i n FW e we s may re late t o adva ntages i n l i vewe i gh t o r t o o t h e r i nd i r e ct e f f ec ts s uc h a s the re l a t ed r e s po n s e s o f woo l gr owt h a nd r e pr oduct i o n t o p h o t ope r i od i c e f f e c t s . As n oted by B l a i r ( 1 9 8 1 ) i t i s a l s o poss i b l e t ha t f i xa t i o n o f s ome ge ne ( o r g enes ) favorab l e f or l amb pr oduc t i on h a s occur r ed . 7 . 1 . 5 Ob jec t i ve s o f t he c u r r e nt r e s ea rch T h e o b j ec t i ve s o f t h i s t r i a l we r e t o : 1 ) e xami ne t he o n s e t a nd d u ra t i o n o f o e s t r us i n f l e ecewe i ght - s e l e cted ( FW ) a nd c ont r o l ( C ) R omney hoggets , 2 ) d e t e rm i ne t he c o n t r i but i on o f w i t h i n - a nd be twe e n ? l i ne d i f f e r e nc e s i n l i ve we i ght , l i vewe i ght ga i n a n d age t o t he observed d i f f e r e nc e s i n the onse t a nd d u ra t i on o f o e s t r us , a nd 3 ) t o o bs e r ve t h e r e l a t i onsh i p b e twe e n t h e i nc i d e nce o f hogge t o e s t r us , woo l g r owth a nd s ubsequent r e p r od uct i on . 7 . 2 MATER I AL S AND METHODS 7 . 2 . 1 Expe r i me nta l p l a n The e xpe r i me n t was c o nd ucted on t h e " Pah i a t ua b l ock " f a rm o f Mas s ey Un i ve r s i ty . A t o ta l o f 1 4 8 ewe hogge ts b o r n e i t he r 1 9 8 4 ( 8 6 ) o r 1 9 8 5 ( 6 2 ) f r om t he f l e ecewe i gh t -se l e cted ( FW ) a nd c ontr o l ( C ) s ub f l o c k s we r e used i n t h e s t ud y . I n 1 9 8 5 a nd 1 9 8 6 t h e r e we r e 6 1 ( 3 0 , 3 1 ) C h ogge t s a nd 8 7 ( 5 6 , 3 1 ) FW h ogge ts p res e n t thr o ughout t he breed i ng s e a s o n ( d e f i ned as 0 3 Apr i l to 2 4 J u l y ) . I n each year , h o gge ts f r om the two s u b f l ocks we r e gra zed t oge t he r . F i g ure 7 . 1 s h ows a ca l e ndar o f events f or t he two years o f data c o l l e c t i on . Ewe l ambs b o r n 1 9 8 4 we r e i nvo l ved i n c oncur rent woo l g r owt h ( Cha pte r 5 ) , a nd s t ap l e s t r e ng th ( Chapte r 8 ) s t ud i e s . 1 2 2 7 . 2 . 2 Rec ord i ng o f r eproduc t i ve act i v i ty a nd gr o wt h Ewe hoggets wer e r u n w i t h vas e c t omi sed S outh S u f f o l k cr os s ram l ambs f r om 0 3 Apr i l unt i l 2 4 J u l y i n both 1 9 8 5 a nd 1 9 8 6 . I n o rder t o ma i nta i n a c onstant ram : ewe r a t i o i n t h e t wo yea rs , t hree r ams we r e u s ed i n 1 9 8 5 wh i l e o n l y t wo we r e n e eded i n 1 9 8 6 . Ram l ambs we r e we l l gr own by t h e s ta r t o f t he b r eed i ng seas o n . Ram mar k e r c rayons and c o l o u r we r e changed eve ry f or t n i gh t a nd checked d ur i ng the i nt e r ve n i ng wee k t o e nsure e f f e c t i ve ne s s . Obs e rva t i on and r e c o rd i ng o f mar k ed ewe hogget s was d one a t t h e e nd o f each 1 4 -day mat i ng pe r i od . Ewe hoggets we r e we i ghed mon t h l y a f te r a n ove r n i ght ( 1 6 hour ) fas t i nd o o r s . Dur i ng t he fa s t i ng pe r i od , r ams we r e k ept s e parate f r om t h e ewe s t o avo i d mi smar k i ngs i n t h e c r owded s hed c ond i t i on s . S even mat i ng per i ods , w i t h f ou r c rayon c o l ours ava i l a b l e , meant t ha t ve ry heavy mar k s had t o be s c rubbed o u t w i t h s oapy wat e r , and l i gh t mar k s r emoved by hand c l i pp i ng , be f o r e s ubseque nt c o l our r ounds we re begun . Co l o u r r ot a t i ons , d i f f e r e n t i n t he t wo year s , a r e a l s o s ho wn i n F i gure 7 . 1 . I n 1 9 8 5 , e we l ambs s howed n o s i gns o f o e s t r us i n t h e f i r s t mat i ng pe r i od s o ram crayons we r e f r e s he nd up a nd used aga i n in the ne xt p e r i od . N o ewe lambs a ppeared t o b e cyc l i ng a f t e r 2 6 June , 1 9 8 5 . Fr om 2 6 June , 1 9 8 5 u nt i l 2 4 J u l y , 1 9 8 5 the rams r ema i ned f i t ted w i th s o f t pur p l e c rayons but n o mar k s we r e f ound . Ye l l ow crayons we r e n o t used i n 1 9 8 6 beca use o f d i f f i c u l ty i n d e tect i ng l i g h t ye l l ow mar k s . A numbe r o f add i t i o na l va r i a b l es we r e f o rmed f r om the t upp i ng and l i ve we i gh t data i n c l ud i ng : Oe s t r us d i s p lay va r i a b l e s : - age a t f i r s t t up ( days ) - we i gh t a t f i r s t tup ( k g ) - l e ng t h o f t he b reed i ng s e a s o n ( number o f mat i ng pe r i od s , 1 - 7 ) - n umber o f mat i ng mar k s ( 1 - 7 ) - pe r i od o f f i r s t ma r k i ng ( 1 - 7 ) - per i od o f l a s t mar k i ng ( 1 - 7 ) - o e s t r o us d i s p layed a t a ny t i me ( O = n o , l =yes ) L i ve we i gh t ga i ns ( kg ) : p o s t -wean i ng ga i n ( 0 4 Apr we i gh t - wea n i ng we i gh t ) - a u t umn ga i n ( 2 4 J u ly we i gh t - 0 4 Apr i l we ight ) - Apr i l ga i n - May ga i n - J une ga i n J u l y ga i n - ga i n t o s hear i ng ( P o s t s hear i ng we i ght - 2 4 J u l y we i gh t ) 1 2 3 L i ve we i ghts we r e n o t c o r r e cted f or d i f f e r e nces i n t he we i ght o f f l e ece ca r r i ed a s mon t h l y wo o l g r owt h ( needed t o obta i n f l e ece - f r e e body we i ghts ) was o n ly ava i l a b l e f or 1 9 8 4 - b o r n h ogge t s . Al l l i vewe i ghts , w i t h the e xcept i o n o f pos t ? s hea r i ng l i vewe i gh t ( 1 4 mon t hs o f age ) , ove r e s t i mate t r ue f l e ece - f r e e l i ve we i ghts a nd a l l l i vewe i gh t ga i ns a r e , c o r r e sp ond i ng ly , b i a sed . 1 2 4 7 . 2 . 3 S ta t i s t i ca l me t h ods 7 . 2 . 3 . 1 Con t i nuous characte r s Un i va r iate a na lys e s o f va r i ance we r e pe r f o rmed o n a l l r e c ords o f h ogget f l e e c e we i gh t , June c l ean wo o l g r owt h , wea n i ng we i g h t , mon t h l y we i ghts du r i ng the breed i ng s eas o n , p o s t - shear i ng l i vewe i ght , l i vewe i gh t ga i ns ove r t h e pos t ? wea n i ng , b r eed i ng a nd pos t -b r eed i ng seas o ns a nd mont h ly l i vewe i ght ga i n ove r the b r e ed i ng s ea s on . The p r e l im i na r y a na lyses i n c l uded a l l ma i n e f f ects a nd f i r s t o r d e r i nt e ract i ons . S e c o nd o r h i gh e r o r d e r i nt e ract i on s we r e a s s umed neg l i g i b l e . S ubsequent t o these pre l i m i na r y a na lyses , i nt e rac t i on s wh i c h wer e c ons i s t e nt ly n o n ? s i g n i f i cant we r e om i t ted f r om t h e mode l t o g i ve : M od e l 7 . 1 y? ? k 1mn = M + a ? + bX ? ? k 1mn + r ? + d k + l 1 + pm + a l ? 1 + r l ? ? + l p1m + e ? ? k 1mn whe r e , y? ? k 1mn = a n o bs e r va t i on on the nth i nd i v i d ua l o f mt " pube r ty s ta tus , j t " b i r t h r an k , k t h dam age , l t h s e l ect i o n l i ne and b o r n i n the i t n yea r , whe r e , M = the u nobse rved popula t i o n mea n , a ? = the f i xed e f f e c t o f the i tn yea r , b = the r e g r e s s i on o f y? ? k 1 mn o n x ? ? k 1mn , x ? ? k 1mn = a n o bs e r ved i nd iv i dua l b i r t h date , r ? = t he f i xed e f f e c t o f t he j t h b i r t h r a n k , d k = t he f i xed e f f e c t o f the k th age o f dam l 1 = t he f i xed e f f e c t of t he l t h s e l e c t i o n l i ne , P= = t he f i xed e f f e c t o f the mth pube r ty s ta t us , a l ? 1 = the f i xed e f f e c t o f the i nte ract i on b etwe e n yea r a nd se l ect i o n l i ne , 1 2 5 r l ::l ? = the f i xe d e f f e c t o f the i nt e r act i o n be twe e n b i r t h r a n k a nd se l e c t i o n l i ne , l p ?rn = the f i xe d e f f e c t o f t h e i nt e rac t i o n be twe e n s e l e c t i on l i ne and pube r ty s tatus , a nd e i. :::l k l.rnn = the random r e s i d ua l a s s oc i a ted w i t h a n observa t i on o n t h e i j k lmnt h i nd i v i dua l . Un i va r i a t e a na lys e s we r e a l s o pe r f o rmed o n ly o n r ec ords o f s he e p wh i c h had d i s p layed o e s t r us as a h ogge t t o e s t ima t e t h e e f f e c t o f s e l e ct i on l i ne a nd o t h e r f ac t o rs o n age a f f i r s t o e s t r us , we i ght a t f i r s t o e s t r us , t he number o f h ogget o e st r us es , t h e l e ngth o f t h e b r e ed i ng s e a s o n a nd t h e pe r i od o f f i r s t a nd last mar k i ng . The mode l used was s im i l a r t o M od e l 7 . 1 wi t h t h e e xc l us i on o f P= a nd i ts i nt e rac t i o n s . Mu l t i va r i a t e ana l yses , n o tab ly r e pe a t -measu r e s ana lys i s , we r e c o nduct e d o n month ly l i vewe i ghts a nd l i ve we i gh t ga i ns d u r i ng t he br e e d i ng s ea s o n , a s we l l a s o n pos t -wea n i ng , b r e ed i ng a nd pos t -breed i ng s e a s o na l l i ve we ight ga i ns . As o ut l i ne d i n Chapt e r 3 , r e peated mea s u r e s ana lys e s we r e us e d t o o bta i n mor e powe r f u l t e s ts o f mea n d i f f e r e nces be twe e n l eve l s o f t h e ma i n e f f e cts i n t h e mod e l a nd t o obta i n d i r e c t e s t i ma t e s o f t i me e f f ects . The und e r l y i ng l i near mode l i nc l ud e d ma i n e f f e c t s , t i me e f f e c t s a nd i nt e ract i ons as o ut l i ned i n Mode l 7 . 1 wi th the i nc l us i o n of p-d i me n s i o na l t i me e f f e c t s a nd t he i nt e r act i ons b e twe e n t i me and d e s i g n f ac t o r s . R e peated measures a na lys e s have bee n d e sc r i bed i n Chap t e r 3 . N u l l hypotheses we r e t e s t e d us i ng t h e Ch i - squa r e d s ta t i s t i c as descr i be d by Mo r r i s o n ( 1 9 7 6 ) . On a w i t h i n- t i me bas i s t h ese r es i d ua l s we r e a s s umed t o be i nd i v i d ua l ly and i nd epe nde n t ly d i s t r i buted , t h e r e be i ng cova r i ances amongst i nd i v i dua l r e s i dua l s a c r o s s t imes d u e t o t h e r e pe a ted na ture o f t he samp l i ng . 7 . 2 . 3 . 2 D i s c r e t e c ha rac t e r s Occur r ence ve r s us n o n- occu r r e nce o f h ogge t o e s t r us was a na lyzed a s a b i na ry va r i a b l e by t he me t h od o f i te ra t i ve r e -we i ghted l ea s t s qua r e s i n a n a na l ys i s o f d e v i a nce 1 2 6 ( G i lmour, 1 9 85 ) . The d e pe ndent va r i a b l e s we re t rans f ormed , pr i or t o a na lys i s , us i ng t he l og i t t rans f orma t i on . The d ev i a nces we r e t e s ted a s Ch i -squa r e va r i a b l e s . Whe n c ova r i a t e s a r e i nc l uded i n l og i t mod e l s , t h e r egress i on c oe f f i c i e nt s ca nno t be s i mp ly i n t e r pr e te d as i n a l i near r e gr e s s i on mod e l . As t h e s e r e g r e s s i on c oe f f i c i e nt s we r e n o t o f pr i mary i nte r e s t i n t h i s s t udy , they wi l l not be d i scussed f u r t h e? e xcept to men t i on t h e i r s ta t i s t i ca l s i gn i f i ca nc e . The mod e l u s ed t o d e scr i be t h e occurr?nce v e r sus n o n ? occur?nce o f h ogge t o e s t r us was a s f o l l o ws : Mode l 7 . 2 : whe r e , Yi :n? ? = an o bs e r va t i on on t h e i nc i d e nce o f o e s t r us i n t he l th ewe h ogge t b o rn i n yea r i , o f b i r t h rank j I i n s e l e c t i on l i ne k , }l = a n u n obs e r ve d popula t i on mea n , a :?. = the f i xed e f f e ct o f t h e i th year b? = the r e gr e s s i o n o f Y:1. :j k ? on X l :1. :j k: ? whe r e , Xl :1. ::l k ? = the o b s er ved b i r t h date o f t h e i j k l t h i nd i v i d ua l , a nd b :z = the r egress i on o f Y:!. :j k ? on X 2 :?. ::l ?c ? whe r e , X2 :?. ::! k ? = the o bs e r ved 3 0 May l i vewe i gh t o f the i j k l th i nd i v i d ua l , r ::l = the f i xe d e f f ec t o f t h e j th b i r t h r ank , l k = the f i xed e f f e c t o f the l th s e l e c t i o n l i ne , a nd e ? ? k 1 = the random r e s i d ua l a s s oc iated wi t h t h e i j k l t n i nd i v i d ua l 1 2 7 Two - t o o t h lamb i ng r e c or d s we r e ana l ysed as a b i nomi a l var i a b l e , and t he e f f e c t o f p r e v i ous o e s t r us s tatus o n two? t oo t h f e r t i l i ty/ f e c und i ty was d e t e rmi ned by : Mode l 7 . 3 y ? ? x = ).l + b X ? ? x + l ? + p ? + 1 p ?.; + e i =' x whe r e , Y1. ::? x = an o bs e r ve d l amb i ng r ec ord o f the k t h e we o f mtn pube r ty s ta t us f r om the l t h l i ne , b o rn 1 9 8 4 , ).l = an unobse r ve d p o pu l a t i on mean , b = the r e g r e s s i on o f Y ? ::? x 1 on x 1. ::? x , whe r e , X 1. ::? x = an i nd i v i d ua l a u tumn p r e -ma t i ng l i ve we i gh t , 1 ? = the f i xe d e f fe c t o f t h e i tn s e lect i on l i ne , i n P ::? = the f i xe d e f f e c t o f t h e j th puberty s t a t us , l p 1. ? = the i nt e r ac t i on o f s e l e c t i on l i ne a nd pube r ty stat us , and e 1. ::? x = the random r e s i d ua l a s s o c i ated wi t h t he i j k t n obs e r va t i o n . 7 . 3 RESULTS 7 . 3 . 1 L i vewe ight Mean l i vewe i ghts o f h ogge t s a t wea n i ng and hogget s he a r i ng a nd d ur i ng the i n t e r ve n i ng b r e e d i ng seas o n are pr e s e nt ed i n Tab l e 7 . la wh i l e t h e r e pea t ed measur es a na lys i s i s i n Tab l e 7 . lb . Exami na t i on o f t h e r e pea t ed mea su r e s ana lyses o f br e ed i ng s e a s o n l i vewe ights s howed h i gh ly s i gn i f i can t month , yea r a nd month by year e f f e c t s . Dam age , date o f b i r t h a nd s e l e c t i o n l i ne a l s o s i gn i f i can t ly a f f ected hogge t l i vewe i ghts . S i gn i f i cant mon t h by se l e c t i on l i ne i n teract i o ns a r o s e f r om i nc r ea s ed s e l ect i on l i ne 1 2 8 s e g r ega t i on as the b r e e d i ng s e a s o n pr og r e s s ed . L i ne d i f f e r e nces became s i gn i f i cant by 2 9 May, and FW hoggets r ema i ned heav i e r t ha n C hogge t unt i l h ogge t s hear i ng . The ove ra l l e f f e c t o f b i r t h r ank was n o t s i gn i f i cant . A s i gn i f i ca n t b i r t h r ank by s e l e c t i on l i ne i n teract i on r e s u l te d f r om tw i n - b o r n h ogge ts o f b o t h l i nes be i ng s im i l a r i n we ight , whe r eas , s i ng l e - b o r n FW h ogget s we r e heav i e r t han s i ng l e -b o r n C hogge ts . Th i s i nt e ract i on was i nd e pendan t o f months . Cyc l i c e we h ogge ts we r e heav i e r t h a n acyc l i c h ogge t s t hr o ughout t h e e nt i r e b r e ed i ng s eas on . Rema i n i ng f i r s t o r d e r i n te rac t i ons we r e n o n -s i gn i f i cant . Wea n i ng we i gh t and pos t -sh ea r i ng l i vewe i gh t we r e ana lysed by s e pa rate ana lys e s o f va r i ance . S i ng l e -b o r n l ambs we r e 3 k g h eav i e r a t wea n i ng t han tw i n - b o r n l ambs . F i ve -year o l d e we s weaned lambs wh i c h we r e 2 - 3 k g heav i e r t han those b o rn t o 2 - , 3 - o r 4 -yea r o ld ewe s . H ogge t s wh i c h cyc l ed we r e 1 k g heav i e r , a t wea n i ng a nd t h r o ughout t he autumn , than acyc l i c h ogge t s . By t h e t ime o f h ogget s he a r i ng n o l i vewe i gh t d i f f e r e nces we r e f ound be twe e n cyc l i c a nd acyc l i c ewe s . S i g n i f i cant i nt e r a ct i ons e x i s t e d be twe e n h ogget o e s t r us d i s p lay s ta tus and a nd s e l e c t i on l i ne . Acyc l i c and cyc l i c C ewe h ogge ts d i d n o t s i g n i f i can t ly d i f f e r i n l i vewe i ght a t any t i me o f t h e yea r , but acyc l i c FW h ogge ts we r e 2 k g l i ghte r than cyc l i c F W ewe s f r om wea n i ng t h r ough t o June . A f t e r t h i s t i me , t he d i f f e r e nce i n l i ve we i ght was reduced t o 1 k g . 7 . 3 . 2 L i vewe i gh t ga i n Month l y l i vewe i gh t ga i ns du r i ng t he br e ed i ng season we r e a na lyzed s e pa ra te ly a nd by r e pea ted measures ana lys i s . P o s t -wean i ng ga i ns , ga i ns ove r t h e b r e e d i ng s eason and ga i ns f r om J u l y t o hogge t s hear i ng we r e s t ud i ed i n a s i mi l a r manne r . Mea n l i vewe i ght ga i ns a r e p r e s e nt ed i n Tab l e 7 . 2 a a nd t he r e pea ted measures a na lys e s a r e p resented i n 7 . 2 b 1 2 9 a nd 7 . 2 c . 7 . 3 . 2 . 1 M onth l y we i ght ga i n i n t h e b r e ed i ng s eas o n . D i f f e r e nc e s i n l i vewe i ght ga i n o ve r t he f o ur months i n t h e b r e ed i ng s e a s o n we r e h i gh l y s i g n i f i ca n t a s we r e yea r a nd mon t h by yea r -e f fec t . S e l e c t i on l i ne d i f f e r e nces we r e a l s o s i gn i f i ca n t w i t h FW h ogge t s ga i n i ng 3 0 0 - 9 0 0 gms mor e t h a n C s he e p ove r f o ur -we e k p e r i ods . Al t h o ug h t h e r e was n o d i f f e r e nce i n l i vewe i gh t ga i n be twe e n cyc l i c a nd n on -cyc l i c h ogge ts , t he r e was a s ugge s t i on o f a l i ne by cyc l i c s ta t u s i nt e ra c t i on ( p < . 1 0 ) s u c h t hat n on - cyc l i c F W s h e e p we r e ga i n i ng mor e t ha n no n-cyc l i c C h o gge ts . N o d i f f e r e nc e s i n l i ve we i g h t ga i n e x i s ted b e twe e n F W and C cyc l i c hogge t s . S e l e c t i o n l i ne by yea r i nt e rac t i o n s we r e s i gn i f i ca n t ( p < . 0 5 ) s uc h t hat i n 1 9 8 5 , s e l e c t i on l i ne d i f f e r e nc e s i n l i vewe i gh t ga i n we r e muc h l a rge r t han i n 1 9 8 6 . I n b o th yea r s , l i n e d i f f e r e nc e s i n l i vewe i ght ga i n we r e mos t p r on o unced i n May a nd J une . 7 . 3 . 2 . 2 Ga i ns p o s t -wea n i ng , over t h e b r e e d i ng s e a s on a nd pos t - br e e d i ng s eas on D i f f e r e nc e s i n l i vewe i gh t ga i n by s e a s o n we r e h i gh ly s i gn i f i ca n t ( p < . O O l ) r e f l e c t i ng d i f f e re n t a r eas o f t h e g r owth curve . Ga i ns i n a l l p e r i od s wer e a f f e c t ed by yea r ( p < . O O l ) a nd s i gn i f i ca n t s e a s o n by yea r i nt e ract i ons we r e p r e s e n t . Twi n-born l ambs ga i ned mor e t ha n s i ng l e b o r n l ambs ( p < . 0 5 ) e s pe c i a l ly in the pos t -wea n i ng pe r i od . Lambs b o r n l at e r i n t h e yea r had gre a t e r gr owt h r a t e s than ear ly-bo r n l ambs ( p < . O O l ) . The e f f e c t o f d a t e o f b i r t h o n l i ve we i g h t ga i n va r i e d wi t h t h e s e a s o n , t h e e f f e c t d ecreas i ng a s l ambs became o l d e r . Cyc l i c a nd n o n -cyc l i c e we s d i d n o t d i f f e r i n l i ve we i gh t ga i n when wea n i ng t o h o gge t s hear i ng was t h e i n t e rva l 1 3 0 7 . 3 . 3 Pube r ty Tab l e 7 . 3a s h ows t h e pe r ce ntage o f ewe h o gge t s i n o e s t r us , c lass i f i ed by s e l e c t i o n l i ne a nd yea r . The a na lys i s o f d ev i ance ( Ta b l e 7 . 3 b ) pr oved t o be qu i te vo l a t i l e w i t h r e s pe c t t o o r d e r o f f i t a nd the d i s t r i but i o n o f i nput d a ta f or var i ous t r a i ts . Da t e o f b i r t h a nd s e l e ct i on l i n e s i gn i f i ca n t l y a f f e c te d t h e a t ta i nme nt o f pube r ty i n t h e s e data . 7 . 3 . 3 . 1 Ons e t o f o e s t r us The t i me o f o ns e t o f t h e b reed i ng s eas o n , a s s e s s e d a s the 1 4 -day per i od i n wh i ch t he f i r s t tupp i ng mar k s we r e o bs e rved , was s i g n i f i ca n t l y a f f ec te d by year . I n 1 9 8 5 , t h e mea n per i od o f f i r s t o e s t r us was 4 . 0 1 ? . 2 7 wh i l e i n 1 9 8 6 i t was pe r i od 2 . 3 7 ? . 1 9 . The s e c o r r e s ponded t o t h e l a s t two we e k s o f May ( 1 9 8 5 ) a nd t he l a s t two we e k s o f Apr i l ( 1 9 8 6 ) . T i me o f o ns e t o f t h e b r e ed i ng s eas o n was una f f ec t ed by d a t e o f b i r t h , d am age , b i r t h r an k , o r s e l e c t i on l i ne a nd t he r e we re n o s i g n i f i ca nt i n t e ract i ons . The mode l e xp la i ne d 4 2 . 5% o f t h e var i a t i on i n d a t e o f f i r s t o e s t r us . Ons e t o f t h e b re e d i ng s e as o n was a l s o e s t imated by t he age a t f i r s t o e s t r us . As t upp i ng mar k s we r e r ead qu i te i n f r eque n t l y ( f o r t n i gh t l y ) , the sma l l e s t e f f e c t i ve d i f f e r e nce t ha t can be i nt e r pr e t ed i s a l s o 1 4 days . H oggets b o rn i n 1 9 8 4 r eache d pube r ty 2 3 days l a t e r tha n 1 9 8 5 -bo r n h oggets ( 2 6 7 ? 4 ve r su s 2 4 4 ? 3 days ) . F o r every day l a t e r i n the year that l ambs we r e bor n , the age a t f i r s t o e s t r us was r educed by . 8 8 ? . 2 3 days . The mode l e xp l a i ned 3 3 . 9 % o f t he var i a t i o n i n age a t f i r s t o e s t r us . The we i ght o f hogge t s a t t h e i r f i r s t o e s t r us was s i gn i f i cant ly a f f e c t e d by da te o f b i r t h a nd s e l e c t i o n l i ne . L i vewe igh t a t f i r s t o e s t r us decreased by 2 0 7 ? 4 4 g f or each day l a ter i n the yea r that hogge ts we r e bo rn . FW h ogge t s 1 3 1 we r e 1 . 7 k g heav i e r than C h ogge ts at the i r f i r s t o e s t r us . The mod e l e xp la i ned 3 1 . 9 % o f t h e va r i a t i on i n we i gh t a t f i r s t o e s t r us . 7 . 3 . 3 . 2 Dura t i on o f o e s tr us The numbe r o f obse rve d o e s t r us e s ( NTUP ) a nd the numbe r o f p e r i ods ove r wh i ch o e s t r us was d i sp l ayed ( LTUP ) we r e b o t h u sed t o d e sc r i be the l e ng t h o f the b r e ed i ng s eas o n . The mod e l e xp l a i ned 2 3% o f the va r i a t i on i n each o f t h e s e t r a i t s . B o t h NTUP a nd LTUP we r e h i g h ly a f f ec ted by yea r , t h e mea ns be i ng ( 1 . 5 6 ? . 2 8 ; 1 . 6 3 ? . 3 5 ) a nd ( 2 . 4 1 ? . 1 9 2 . 8 8 ? . 2 4 ) i n 1 9 8 5 a nd 1 9 8 6 , r e s pe c t i ve ly . Se l e c t i o n l i ne e f f e c t s ( C : FW ) f or NTUP ( 1 . 8 3 ? . 2 8 : 2 . 1 6 ? . 1 7 ) a nd L TUP ( 2 . 0 4 ? . 3 5 : 2 . 4 8 ? . 2 1 ) a pp r oache d s i gn i f i cance ( p < . l O ) . N o s e l e c t i on l i n e by year i nt e ract i ons wer e s i gn i f i cant . Whe n yea r s we r e ana lysed s e pa ra t e ly s e l e c t i o n l i ne e f f e c ts we r e n o n - s i gn i f i ca nt i n 1 9 8 5 wh i l e t h e a s s o c i ated s e l e c t i on l i n e p r o ba b i l i t i e s f o r NTUP a nd LTUP i n 1 9 8 6 we re 5 . 1% and 6 . 8 % . 7 . 3 . 4 Re l a t i o ns h ip o f h ogge t o e s t r us t o wo o l gr owth Mea n greasy h ogge t f l e e c e we i ghts f o r each yea r , s e l e c t i o n l i ne a nd o e s t r us s tatus a r e g i ven i n Tab l e 7 . 4 . H ogge t g r easy f l e ec e we i ght was una f f e c t ed by whe ther o r n o t t h e e we h ad prev i ous l y d i s p l ayed o e s t r us . No i nt e r ac t i on s e x i s t ed be twe e n s e l e c t i o n l i ne a nd o e s t r us sta t us . W i n t e r c lean wo o l gr owt h , d e f i ne d a s c l ean wo o l gr owth d ur i ng June , was una f f e c t e d by hogge t o e s t rus s ta t us and n o i nt e ract i ons e x i s t ed amongs t o ther factors . 7 . 3 . 5 Re la t i o ns h i p o f h ogge t o e s trus t o two - t o o t h lamb i ng pe r f ormance The p r e s e nce o r abs ence o f hogget o e s t r us prod uced marg i na l ly ( . 0 5 < p < . l 0 ) s i gn i f i cant e f f ects on two - t o o t h 1 3 2 l amb i ng pe r f o rma nce . O f the two - t o o th e we s pre s e nt a t l amb i ng , s l i gh t l y l e s s t han ha l f o f t h e m had a l r e ady be e n cyc l i c a s hogge t s . O f t he prev i o us l y cyc l i c FW e we s , a l l l ambe d . E i gh ty pe r c e nt o f prev i o u s l y cyc l i c C hogget s a nd 6 5 - 6 9 % o f the p r ev i o u s ly n o n -cyc l i c e we s lambed ( Ta b l e 7 . 5 ) . I n t he C ewe s , p r ev i ous l y acyc l i c e we h o gge ts l e f t mor e p r ogeny than p r ev i o u s l y cyc l i c h o gge t s ; whe r eas , t he c onve r s e was t r ue o f FW hogget s . O f t h e e we s l amb i ng ( 4 0 / 5 2 ) 6 FW e we s a nd l C ewe gave b i r t h t o tw i n s . L i ne d i f f e r e nces i n pr o l i f i cacy appr oached s i gn i f i ca nce ( . 0 5 < p < . 1 0 ) . H i gh l amb mo r ta l i ty i n the 1 9 8 6 s e a s o n r e s u l t e d i n 2 6 % l os s e s ( 1 5 l ambs ) f r om b i r t h t o wean i ng . 1 3 3 F i gur e 7 . 1 Ca l e ndar o f e ve nts f o r e we hogge t s 2 3 AUG 8 4 - lambs b o r n 1 2 AUG 8 5 - 0 8 OCT 8 4 I 2 6 SEP 8 5 I 2 6 NOV 8 4 l ambs wean ed 2 2 NOV 8 5 I 1 2 DEC 8 4 lambs s h o r n 2 0 DEC 8 5 I we igh h ogge t s 0 4 APR 8 5 c rayons o n r ams 0 3 APR 8 6 & j o i n w i t h r ams ye l l ow I g r e e n 1 7 APR 8 5 r e ad mar k s & 1 7 APR 8 6 c ha nge c rayons ye l l ow I b l ue 0 1 MAY 8 5 we i gh h ogget s 0 1 MAY 8 6 & r e ad mar k s & c ha nge c rayons gr e e n I red 1 5 MAY 8 5 r ead mar k s & 1 5 MAY 8 6 c ha nge c rayons b l ue I gre e n 2 9 MAY 8 5 we i g h hogge ts 2 9 MAY 8 6 & r ead mar k s & c ha nge c rayons r ed I b l ue 1 2 JUN 8 5 r ead mar k s & 1 2 JUN 8 6 c hange c rayons gr e e n I r ed 2 6 JUN 8 5 we i gh h o gget s 2 6 JUN 8 6 & r e ad mar k s & change c rayons pur p l e I g r e e n 1 0 JUL 8 5 r ead mar k s & 1 0 JUL 8 6 c hange c rayo ns pur p l e I purp l e 2 4 JUL 8 5 we i gh hogge ts 2 4 JUL 8 6 & r ead mar k s & r emove c rayons I 1 7 OCT 8 5 s he a r h o gge t s 2 7 S EP 8 6 & we i gh h ogget s 1 3 4 Tab l e 7 . 1 The l i vewe i gh t of ewe hogget s ( k g ) 7 . 1 a Year , b i r t h r an k , da111 a ge , sel ec t i on l i ne and oest rus s ta tus l east squares 111eans . Cl assi f i c at i on n Wean i ng 04APR 0 1 MAY 29MAY 26JUN 24JUL PSW 1 ================================================================================= Over al l 1 4 8 20 . 7 ! . 3 28 . 2 ? . 3 29 . 7 ? . 3 30 . 3 ? . 3 30 . 4 ? . 4 3 1 . 0 ? . 3 33. 7 ? . 3 Year 1 985 86 2 1 . 7 ? . 3 28 . 2 ? . 4 29 . 0? . 4 29 . 4 ? . 4 30 . 0 ? . 4 32 . 2 ? . 4 39 . 4? . 4 1 986 62 1 9 . 2 ? . 4 28 . 3? . 6 3 0 . 6 ! . 5 3 1 . 2 ? . 5 3 0 . 9 ? . 6 29 . 9 ? . 6 25. 7? . 6 born s i n g l e 7 2 22 . 0 ? . 4 28 . 9? . 4 30. 4? . 4 3 1 . 0? . 4 3 1 . 0? . 5 3 1 . 6? . 4 33. 5 ? . 5 t w i n 7 6 1 8 . 9? . 3 27 . 5! . 5 29 . 0 ? . 4 29 . 6 ? . 4 29 . 9? . 5 30 . 5? . 5 3 1 . 9 ? . 4 Da11 2yr 35 1 9 . 9? . 5 28 . 3? . 6 29 . 3? . 6 29 . 8 ? . 6 3 0 . 5 ? . 7 30 . 8 ? . 6 3 1 . 8? . 6 3yr 38 19. 7 ? . 5 27 . 3? . 6 29 . 0 ? . 6 29 . 4 ? . 6 29 . 8? . 6 29 . 9? . 6 3 1 . 5? . 6 4yr 32 20. 9? . 5 28 . 3 ? . 7 29 . 5? . 6 30 . 5 ? . 6 30 . 1 ? . 7 3 1 . 0 ? . 6 32 . 2 ? . 6 5yr 43 2 2 . 2 ? . 5 29 . 1 ? . 6 30 . 8! . 6 3 1 . 5 ? . 6 3 1 . 5? . 7 32 . 4? . 6 34 . 2 ? . 7 L i ne c 6 1 20 . 2 ? . 4 2 7 . '3 ? . 5 29 . 4 ! . 4 29 . 7 ? . 4 29 . 5 ! . 5 30 . 1 ? . 5 3 1 . 5? . 5 FW 87 20 . 6? . 3 28 . 5 ? . 4 30 . 0 ? . 4 30 . 9 ? . 4 3 1 . 4? . 5 32 . 0 ? . 4 33. 5 ? . 4 Oest rus A cyc l i c 64 1 9 . 7:!: , 4 27 . 6? . 5 29. 0? . 5 29 . 7 ? . 5 29 . 6 ? . 6 30 . 5? . 5 32 . 0 ? . 6 Cyc l i c 84 20 . 6 ! . 3 28 . 7 ? . 5 30 . 4? . 4 30 . 9 ? . 4 3 1 . 3? . 5 3 1 . 6 ? . 4 33. 1 ? . 5 c Acyc l i c 34 20 . 3? . 3 27 . 9 ? . 7 29 . 2 ! . 6 29 . 6 ? . 6 29 . 1 ? . 7 29 . 8? . 7 3 1 . 3 ? . 8 Cyc l i c 2 7 20 . 0? . 3 27 . 7 ! . 7 29 . 7 ? . 7 29 . 8 ? . 6 30 . 1 ? . 8 30 . 5 ? . 7 3 1 . 9 ? . 7 FW Acyc l i c 30 1 9 . 2? . 2 27 . 3? . 7 29 . 2 ? . 7 30 . 2 ! . 6 30 . 7 ? . 7 3 1 . 6? . 7 32 . 5 ? . 6 Cyc l i c 57 2 1 . 3 ? . 3 29 . 7 ? . 5 3 1 . 1 ? . 4 32 . 0 ? . 4 32 . 6? . 5 32 . 8 . ? 5 34 . 1 . ?7 c S i n g l e 35 2 1 . 6? . 5 27 . 8 ? . 6 29 . 5? . 6 29 . 7 ? . 5 29 . 4? . 6 30 . 0 ? . 6 3 1 . 7 ? . 6 T w i n 26 1 9 . 3 ? . 6 28 . 1 ? . 7 29 . 3 ? . 7 29 . 7 ? . 6 29 . 5 ? . 7 30 . 2 ? . 7 3 1 . 5? . 6 FW S i n g l e 3 7 22 . 4 ? . 5 29 . 9? . 6 3 1 . 3? . 6 32 . 4 ? . 6 32 . 6? . 7 33. 3 ? . 6 34 . 7? . 6 T w i n 5 0 1 8 . 2 ? . 4 27 . 0? . 5 28 . 6? . 5 2'3 . 5 ? . 5 3 0 . 2 ? . 6 30 . 7 ? . 5 3 1 . 9 ? . 7 ==================================================================================== 1 PSW i s p os t shear i n g l i ve wei g h t a t hogget shea r i n g Ta b l e 7 . 1 b Repeat ed mea s u r e s S ou rc e F'-'LL MODEL F0L L MODEL T I MES YEAR DATE OF B I RTH AGE OF DAM S ELECT I ON L I NE YES/NO OESTRUS YES /NO OESTRUS YEAR X L I NE T I ME S X YEAR T I ME S X AGE OF T I ME S X B I RTH T i ME S X L I NE T I ME S X YES/NO T I ME S X YEAR X T I ME S X L I NE X T I ME S X L I NE X * P < . 0 5 * * P < . 0 1 * * * P < . 0 0 1 CYCLE S X L I NE DAM DATE OES TRUS L I NE B I RTH DATE YES/NO OESTR d f 1 0 6 0 1 1 3 1 1 1 1 6 1 8 6 6 6 6 6 6 1 3 5 a na lys i s o f l i ve we i gh t Ch i - Squar e 3 2 9 . 0 * * * 5 7 6 . 5 * * * 3 3 . 9 * * * 3 1 1 . 3 * * * 6 . 7 P < . 1 0 6 . 1 * 1 7 . 7 * * * 0 . 2 ns 0 . 1 ns 2 1 7 . 6 * * * 2 6 . 2 P < . 1 0 1 . 1 ns 2 7 . 9 * * * 1 1 . 5 P < . 1 0 7 . 1 ns 3 . 7 ns 5 . 9 ns Tab l e 7 . 2 L i vewe 1 g h t g a 1 n o f ewe hog g e t s l k g l . 7 . 2a Year , b i r t h r a n k , daa a g e , sel ec t i on l i n e and oest r u s s t a t u s l east squares teans Cl ass i f i c a t i on n APR-JUL APR MAY JUN JUL JUL -PS\tF =================================================================================== Overa l l Year Bor n Daa l i n e 1 985 1 98& S i ng l e T w i n 2yr 3yr 4yr 5yr c FW 1 4B B6 62 72 7& 35 3B 32 43 6 1 B7 B . 0! . 2 6 . & ? . 3 9 . 4 ? . 3 7 . 1 ? . 3 B . 9? . 3 B . 6? . 4 7 . 7? . 4 7 . 5 ? . 5 B . 3? . 1 7 . 5 ? . 3 B . 5 ? . 3 4 . 1 :! . 3 1 . 3 ! . 3 2 . 6 ? . 3 2 . 8 ? . 3 2 . 4 ? . 4 2 . 9 ? . 4 2 . & ? . 4 2 . 9 ? . 4 2 . 1 ? . 3 3 . 3? . 3 Oes t r us Acyc l i c 64 Cyc l i c 84 7 . 9? . 4 8 . 2? . 3 2 . 8 ? . 3 2 . 7 ? . 3 1 985 c FW 3& 6 . 3? . 5 3 . 0 ? . 4 5 0 6 . 9? . 4 5 . 1 ? . 3 1 . 5 ? . 2 0 . 9? . 2 2 . 2 ! . 2 1 . &? . 2 1 . 5 ? . 2 1 . 1 ? . 3 1 . 8 ? . 3 1 . 3? . 3 1 . B ? . 3 1 . 5 ? . 2 1 . 5 ? . 2 1 . 5 ? . 2 1 . 6 ? . 2 0 . 6 ? . 1 0 . 4 ? . 2 0 . 8 ? . 2 0 . 6t . 2 0 . 6 ? . 2 0 . 5 ? . 2 0 . 4 ? . 3 1 . 0? . 2 0 . 6 ! . 2 0 . 3? . 2 0 . 9 ? . 2 0 . 7 ? . 2 0 . 5 ? . 2 0 . 8 ? . 3 0 . 0? . 3 0 . 9? . 2 O . B? . 2 0 . &? . 2 -0 . 2 ? . 3 0 . 0 ? . 2 0 . 4 ? . 2 0 . B ? . 3 0 . 4 ? . 3 - 0 . 3 ? . 3 0 . 0 ? . 3 - 0 . 1 ? . 2 0 . 6 ? . 2 0 . 4 ? . 2 2 . 1 ? . 2 - 1 . 2 ? . 3 0 . 4 ? . 2 0 . 4 ? . 2 0 . 1 ? . 3 0 . 0? . 3 0 . 7? . 3 0 . 9 ? . 3 0 . 5 ? . : 0 . 4 ? . 2 0 . 0? . 2 0 . 7 ? . 3 0 . 4 ? . 2 0 . 2? . 2 1 . 4 ? . 1 7 . 0? . 3 -4 . 2 ? . 3 ! . 5 ? . 2 1 . 3? . 2 1 . 2 ? . 2 1 . 5 ? . 3 1 . 3 ? . 3 1 . b? . 2 1 . 5 ? . 2 ? l 2 ? . 3 1 . 4? . 3 0 . 1 ? . 3 2 . 1 ? . 4 7 , 1 ? . 3 1 . 1 ? . 2 2 . 1 ? . 3 6 . 8? . 5 1 986 c FW 25 B . 7? . 5 1 . 2? . 4 2 . 2 ? . 3 0 . 6? . 3 -0 . 4 ? . 3 - 1 . 2 ? . ? -4 . 0 ? . 4 3 7 1 0 . 2? . 5 1 . 4 ? . 5 2 . 1 ? . 4 1 . 1 ? . 3 0 . 0 ? . 4 - 1 . 3 ? . d -4 . 4 ? . 5 =================================================================================== 1 Post wean i n g g a i n 2 Post shear i ng 1 3 6 Tab l e 7 . 2 b R epeated mea s u r e s 1 i vewe i ght ga i ns S ource FULL MODEL FULL MODEL T I ME S YEAR DATE OF B I RTH AGE OF DAM S ELECTI ON L I NE YES/NO OES TRUS YES/NO OESTRUS YEAR x L I NE T I MES X YEAR T I MES X AGE OF T I MES X L I NE T I MES X YES/NO T I ME S X YEAR X T I ME S X L I NE X T I MES X L I NE x * P < . O S * * P < . 0 1 * * * P < . 0 0 1 CYCLE S x L I NE DAM OES TRUS L I NE B I RTH RANK YES /NO OESTR d f 1 0 2 0 1 1 3 1 1 1 1 2 6 2 2 2 2 2 1 3 7 a na lys i s o f s e a s o na l Ch i - Squa r e 2 1 7 . 1 * * * 2 3 2 . 2 * * * 1 2 5 . 1 * * * 1 5 3 . 8 * * * 1 . 5 n s 2 . 7 n s 0 . 6 n s 2 . 7 ns 0 . 4 n s 9 8 . 5 * * * 2 . 8 n s 5 . 7 p < . 1 0 6 . 1 * 3 . 3 ns 2 . 7 ns 0 . 7 ns Tab l e 7 . 2 c R e pea t ed mea s u r e s l i vewe i gh t ga i ns s eas o n . S ou r c e FULL MODEL FULL MODEL T I ME S YEAR DATE OF B I RTH AGE OF DAM S ELECT I ON L I NE YES/NO OESTRUS CYCLES YES/NO OESTRUS x L I NE YEAR X L I NE T I ME S X YEAR T I MES X AGE OF DAM T I MES X L I NE T I MES X YES/NO OESTRUS T I MES X YEAR T I ME S X L I NE T I MES X L I NE * P < . 0 5 * * P < . 0 1 * * * P < . 0 0 1 X L I NE X B I RTH DATE x YES/NO OES TR d f 1 0 3 0 1 1 3 1 1 1 1 3 9 3 3 3 3 2 1 3 8 a na lys i s o f mon t h l y dur i ng t he b reed i ng Ch i - Squa r e 7 1 . 9 * * * 1 7 4 . 2 * * * 5 3 . 5 * * * 0 . 1 ns 4 . 4 ns 1 0 . 1 * * 0 . 7 ns 3 . 1 p < . 1 0 6 . 1 * 1 4 4 . 8 * * * 1 4 . 5 ns 5 . 7 ns 2 . 6 ns 0 . 5 ns 1 . 1 ns 0 . 5 ns Tab l e 7 . 3a P e r c entage o f e we lambs i n oe s t r us by s e l e c t i on l i ne . L i ne 1 9 8 5 1 9 8 6 I Ove f"a.l l I - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1 - - - - - - - - - 1 I I Contro l 2 3 . 7 6 4 . 5 I 4 4 . 3 I I I F le e c e We ight 5 3 . 6 8 7 . 1 I 6 5 . 5 I I I - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1 - - - - - - - - - 1 Ove ra.H 4 3 ? 0 7 5 ? 8 I 5 6 ? 8 I - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1 - - - - - - - - - 1 1 3 9 Tab l e 7 . 3 b Ana l ys i s o f d ev i ance f or ye s/no d i s p lay o f o e s t rus a s a h ogge t . S o urce d f YEAR 1 B I RTH DATE 1 L I VEWE I GHT 1 B I RTH RANK 1 S ELECT I ON L I NE 1 * * * P< . 0 0 1 * * P < . 0 1 * P < . 0 5 D ev i anc e 1 6 . 3 1 1 7 . 9 9 . 1 4 2 . 1 4 7 . 0 5 ns non s i gn i f i ca n t . * * * * * * * * ns * * Tab l e 7 . 4 C l ean hogge t f l e ec e we i ght ( CFW ) and w i n t e r woo l gr owth ( J une g c l e an woo l /head/day ) i n cyc l i c and acyc l i c FW a nd C hoggets . C l a s s i f i cat i on CFW ( kg ) June woo l ( g/day ) = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Ove ra l l 3 . 0 ? . 1 7 . 8 ? . 3 Y ear 1 9 8 5 4 . 1 ? . 1 7 . 8 ? . 3 1 9 8 6 3 . 1 ? . 1 b o rn s i ng l e 3 . 7 ? . 1 7 . 6 ? . 4 twin 3 . 6 ? . 1 8 . 1 ? . 4 Dam 2yr 3 . 7 ? . 1 7 . 9 ? . 5 3yr 3 . 6 ? . 1 7 . 8 ? . 5 4 yr 3 . 4 ? . 1 8 . 5 ? . 5 5yr 3 . 8 ? . 1 7 . 1 ? . 5 L i n e c 3 . 1 ? . 1 6 . 4 ? . 5 FW 4 . 1 ? . 1 9 . 3 ? . 3 Oe s t r us Acyc l i c 3 . 6 ? . 1 7 . 7 ? . 3 Cyc l i c 3 . 6 ? . 1 8 . 0 ? . 5 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Tab l e 7 . 5 Two -tooth lamb i ng pe r f o rmance o f e we s wh i ch we r e e i th e r cyc l i c o r a cyc l i c as hoggets i n FW and C l i ne s ( n ) . S e l e c t i on L i ne Pube r ta l S tatus P e r c e ntage Lamb i ng Perce ntage Twi n -bea r i ng 1 4 0 C ( 2 5 ) ! - - - -Cyc l i c ( 5 ) - - - - 8 0% ( 4 ) - - - - - - - 2 5% ( 1 ) - - 1 4 % I - - - -Acyc l i c ( 2 0 ) - - - 6 5% ( 1 3 ) - - - - - - - 0% ( 0 ) - - 1 F W ( 2 7 ) ! - - - -Cyc l i c ( 1 4 ) - - 1 0 0% ( 1 4 ) - - - - - - 2 9 % ( 4 ) - - 1 2 2 % ! - - -Acyc l i c ( 1 3 ) - - - 6 9 % ( 9 ) - - - - - - 2 2 % ( 2 ) - - 1 1 4 1 7 . 4 D I SCUS S I ON 7 . 4 . 1 Ewe hogge t l i vewe igh t T h e mea n l i ve we i ght o f e we hogg e t s d u r i ng the bre ed i ng s e a s o n was l e s s than the 3 3 - 3 5 k g n orma l ly r ec ommended targe t we i ght ( Da l t on , 19 8 1 ) . Al t hough l i vewe i ght was mea s u r ed o n f a s ted ewe s , t h e l i v ewe? ghts o f 3 0 k g i n May , J une a nd J u l y a r e l e ss tha n t h o s e r e por ted i n o ther s tud i e s o f R omne y e we h oggets a t Mas s e y Un i ve r s i ty ( McM i l l a n , 1 9 8 1 ; As o f i , 1 9 8 4 ) . The l i ve we i ght advantage o f s i ng l e - over twin-born lambs was l e s s t ha n that r epor ted a t wea n i ng ( Ba k e r et a l . , 1 9 7 4 ) o r dur i ng a u tumn ( Ch ' a ng and Rae , 1 9 6 1 ; 1 9 7 0 ; Ba k e r e t a l . , 1 9 7 9 ) . The use o f b i r th rank , r a t h e r t han rear i ng rank , i s a s s umed n o t t o have grea t l y a f f e c t e d the r e su lts a s o n ly 1 1 lambs b o r n a s twi ns rema i ned a s s i ng l e s a t wea n i ng . Ch ' a n g a n d Ra e ( 1 9 7 0 ) and Bak e r e t a l . ( 1 9 7 4 ) have e s t i mated tha t l i ve we ight d i f f e r e nces betwe e n t w i n s r eared as s i ng l e s a nd tw i n s r e a r ed a s twi ns we r e be t we e n 2 5% and 5 0% o f t h e mag n i tude o f tw in - vs . s i ng l e - b o rn c ompa r i sons . Thr oughout the e nt i r e i nt e r va l f r om wea n i ng to hogget s h e a r i ng FW e we hogge ts we r e h ea v i e r than C hoggets , t h e d i f f e r e nce bec om ing and r ema i n i ng s i g n i f i cant by June . T h i s d i f f e r e nce ( + 1 kg ) i nc l ud e s d i f f e r e nces i n the we i gh t o f wo o l c a r r i ed . H i st or i ca l ly , F W h o ggets a r e 1 . 5 - 2 k g h eav i e r t ha n C hoggets a f t e r hogge t s hear i ng ( B la i r , 1 9 8 6 ) . As d i scuss ed i n Chapter 5 , t h i s d i f f e r e nce accrues s l owly , i s u sua l ly s i gn i f i cant by l ate a u t umn o r ea r ly w i n te r , a nd i nc r e a s e s s l i gh t ly i n ear l y s pr i ng pr i or to hogget s h ear i ng . Oe s t r ous FW hoggets we r e appr o x i ma t e ly 2 kg heav i e r than acyc l i c FW lambs wh i le o e str ous a nd anoestr ous C lambs d i d n o t d i f f e r i n l i vewe i ght . D i f f e r e nces i n autumn l i vewe i gh t 1 4 2 o f 2 to 3 k g be twe e n o e s t r us a nd n o n - o e s t r us e we hoggests have b e en r e po r ted f or R omney lambs e l s e whe r e ( Ch ' a ng and Rae s i d e , 1 9 5 7 ; H i ght e t a l . , 1 9 7 3 ; As o f i , 1 9 8 4 ) . McM i l l a n ( 1 9 8 1 ) f o und no d i f f e r e nce i n we i ght be twe e n o e s t r ous and a noes t r ous Bord e r L e i ce s t e r X Romney l ambs wh i l e o e s tr ous R omney l ambs we r e 5 - 6 kg heav i e r a t j o i n i ng t ha n anoest r ous lambs . Al l i s o n ( 1 9 7 5 ) has a l s o d emo ns t rated b reed d i f f e r ences i n we i gh t b e twe e n mar k ed a nd u nma r k ed e we lambs e ve n whe n b r e ed d i f f e re nces in j o i n i ng l i ve we i ght we r e sma l l . The poss i bl e n e u r oendoc r i ne pat hways th r ough wh i c h body we i ght a nd gr owth i n f o rma t i on i n f l ue nce the s e ns i t i v i ty o f t h e p r e pube r ta l s h e e p ' s hypotha lamus t o t he nega t i ve f e e d back o f o e s t rad i o l on L H s e c r e t i on a r e r e v i e wed a nd d i scussed b y Fos t e r e t a l . ( 1 9 8 6 ) . 7 . 4 . 2 L i ve we ight ga i n P ost -wea n i ng l i vewe i gh t ga i ns we r e g r e a t e r i n 1 9 8 6 but ga i ns ove r the b r e ed i ng a nd pos t -br e ed i ng s e a s o ns we r e s ubstant i a l ly l owe r i n 1 9 8 6 than i n 1 9 8 5 . The s e d i f f e r i ng pa tte r ns o f body g r owt h we r e due , i n pa r t , t o a d ry autumn i n 1 9 8 5 , wh i ch r educed pastu r e gr owth unt i l May, a nd par t ly due t o a p o o r wi nte r a nd ove r s tock i ng o f t he r e s e a r ch b l oc k p r ope r ty w i t h catt l e , i n 1 9 8 6 . Twi n-born lambs had h i ghe r l i ve we i ght ga i ns ove r a l l s eas ons wh i ch i nd i cated c ompensatory p ost -wea n i ng g r owt h . As noted i n othe r s t ud i e s t h i s d i f f e r e nce i n l i ve we i ght ga i n d ecreases w i t h i nc r eas i ng age ( Ch ' ang a nd Rae , 1 9 7 0 ; H i ght a nd Jury, 1 9 7 1 ; McM i l l i a n , 1 9 8 1 ) . S i gn i f i ca nt s e l e ct i on l i ne d i f f e r e nces ( FW > C ) e x i s t ed o n ly i n May a nd June , the d i f f e r e nces i n a l l o t he r pe r i ods be i ng non-s i gn i f i cant . Ge ne r a l ly , und e r c ond i t i o? f or ade quate g r owth , FW a n i ma l s g rew fas t e r than C a n i ma l s . I n p e r i ods of poor e r n u t r i t i on l i ne d i f f e r e nces we r e undet e c ta b l e . 1 4 3 7 . 4 . 3 P ube r ty 7 . 4 . 3 . 1 I nc i d e nc e o f o e s t r u s T h e l e ve l s o f o e s t r o us act i v i ty i n F W ( 6 5 . 5% ) a nd C ( 4 4 . 3 % ) R omne y e we h ogge ts we r e c ompar ab l e t o those o f o t he r New Z e a l and Romney s t ud i e s ( Ch ' a ng a nd Ra e s ide , 1 9 5 7 ( 7 2 % ) ; H i gh t e t a l . , 1 9 7 3 ( 5 5% ) ; A l l i s on e t a l . , 1 9 7 5 ( 4 3 % ) ; Meye r a nd F r e nc h , 1 9 7 9 ( 2 5% ) ; McM i l la n , 1 9 8 1 ( 8 9 % ) ; As o f i , 1 9 8 4 ( 7 9 % ) ) . Var i a t i on i n t he i nc i d e nc e o f oestr ous be twe e n s t ud i e s i s o f te n a t t r i buted t o d i f f e r e nc e s i n a u tumn l i ve we i ght ( Mo o r e a nd McM i l la n , 1 9 8 4 ) . The mea n i nc i d enc e o f o e s tr us ( 5 7 % ) i n t h i s s t udy appea r s r easona b l e g i ve n a ut umn l i vewe i ghts o f a b out 3 0 k g . Ca r e mus t be t a k en whe n d i s p lay o f o e s tr ous , r ather than the e s ta b l i s hment o f r e gu l a r ova r i a n cyc l e s , i s t h e t r a i t used to d e s cr i be pube r t y . The r e c o rd i ng o f o e s trous d i s p lay r e l i e s on adequate s e a s o na l p r e parat i on a nd l i b i d o o f t he rams , phys i ca l a nd v i s ua l p r o x i mi ty o f e wes and rams i n the paddock and the r e l i ab i l i ty a nd c o nd i t i on o f t h e r am ' s ma r k i ng d ev i ce . Als o , ovu la t i ons i n pre pube r ta l e we s may n o t a lways be accompan i e d by outward be hav i or a l o e s t r us ( Ha r e a nd Brya nt , 1 9 8 2 ) . T h e a\..\thor a l s o ass umes that t h e s e p h en omena occur equa l ly i n FW a nd C s he e p . B o th appr opr i a te photope r i od i c a nd l i vewe ight s i gna l s a r e r e q u i r ed f or t h e o ns e t o f p u be r ty . Ma l nour i s hed f e ma le s have f unc t i ona l pho t orece pt i ve mec ha n i sms but a n appr opr i a t e r e sponse t o p e rmi s s i ve photope r i od w i l l be man i f e s t o n ly whe n they a ch i e ve the appropr iate p hys i o l og i ca l s i ze . As men t i oned e ar l i e r , t h i s man i f e s ta t i o n i nvo l ve s a r ed uc t i on i n hypotha lam ic s e ns i t i v i ty t o the n egat i ve f e edback act i o n o f o e s trad i o l o n L H s e c r e t i on ( Fo s t e r e t a l . 1 9 8 6 ) . I t i s p oss i b l e that gene t i c var i a t i on e x i s t s i n t he 1 4 4 '' t r i gge r " l i vewe i ght r equ i red t o i n i t i a te o e s t r ous cyc l e s i n photope r i od i ca l ly r e c e pt i ve e we s . Ge ne t i c var i a t i o n i n photope r i od i c s e ns i t i v i ty i s a l s o pos s i b l e and i s s uppor t ed by e v i de nc e i n va r i ous s tra i ns o f m i c e ( Heath a nd Lynch , 1 9 8 2 ) . As d i scussed by Montgome r y and Hawker ( 1 9 8 6 ) , the i nt e r -conne c t i on o f c ommon neur oendocr i ne mecha n i sms a f f e c t i ng b o t h woo l g r owt h a nd r e pr od uc t i on may have s ome r e l e vance g i ve n t h e h i gh e r w i n t e r woo l g r owt h ( Chapte r 5 ) a nd w i n t e r wo o l g r owt h e f f i c i e ncy ( Chapte r 6 ) o f FW s h e e p . The 1 k g l i ve we i gh t advantage o f FW e we hoggets s e ems i ns u f f i c i e nt t o a ccoun t f o r the 2 0 - 2 5% advantage i n numb e r o f o e s t r ous e we s . M o o r e a nd McM i l l a n ( 1 9 8 4 ) s ugges t a 3 % adva ntage f o r e a c h 1 k g i nc r ease i n we i ght , a l though the l i near i t y o f t h i s r e l a t i onsh i p ove r a range o f l i ve we i gh t s was n o t d i s c uss ed . I n s ome way , FW s he e p may have a n a l t e r ed r e s po n s e o r s e n s i t i v i ty t o me l a t on i n . D i f f e r e n c e s i n produc t i o n , o r c le a rance r a t e s f r om c e r e bra l t i s s ue s , o f me l a t on i n a r e a l s o p o s s i b l e . W i t h out d i scuss i ng the rami f i cat i ons o f h i s r e s u l t , Ha l e s ( pe r s . comm . ) h as f o und h i ghe r ( 2 X n o rma l ) b l ood f l ow r a t e s to the p i nea l g l a nd o f f le e cewe i ght -s e l e c t ed Me r i no s wh i l e t ha t i n C s he e p was c ons i d e r ed " no rma l " . F o ster e t a l . ( 1 9 8 6 ) ma i nta i n that nutr i t i ona l cues a r e t rans la ted mo r e d i r e c t l y , a nd h ence mo r e rap i d ly , than photoper i od i c cues s uc h that s udden i ncreases in nutr i t i on a r e o f t en q u i t e e xped i e nt i n has t e n i ng pube r ty . The i ncreased gr o wt h r a t e s a nd l i vewe i ghts dur i ng the e ar ly breed i ng s e a s o n o f 1 9 8 6 may have b e e n r e s pons i b l e f or t h e ear l i e r ons e t o f o e s t r u s i n 1 9 8 5 - vs . 1 9 8 4 - born e we s . I n agreement w i t h McM i l la n ( 1 9 8 1 ) the pea k o est rus act i v i ty was i n l a t e May dur i ng b oth year s . 1 4 5 7 . 4 . 3 . 2 Dura t i o n o f the br e e d i ng s eason The mean number o f o e s t r us cyc l e s ( 1 . 6 ) agrees we l l w i t h o t h e r pub l i s hed e s t i ma t e s f o r Romney e we lambs i n N ew Z e a l and ( Ch ' ang a nd Rae s i d e , 1 9 5 7 ( 2 . 7 ) ; H i ght e t a l . 1 9 7 3 ( 1 . 4 ) ; Bak e r e t a l . 1 9 7 4 ( 1 . 7 ) ) . H i gher va lues ( 3 . 5 ) have b e e n f ound by McM i l lan ( 1 9 8 1 ) . T h e durat i on o f t h e b reed i n g s eason i n e we hogg e t s has p ract i ca l i mp l i cat i ons . Ch ' a ng and Rae ( 1 9 7 0 ; 1 9 7 2 ) have a dvocated i ts use in ea r l y i nd i rect s e l e c t i o n f o r f e cund i ty . Montgome ry a nd Hawk e r ( 1 9 8 7 ) have d emo n st ra t ed a pos i t i ve r e lat i onsh i p be twe e n ovu la t i o n rate a nd t h e l e ngth o f t h e br e ed i ng s e a s o n i n adu l t e we s . Whe r e mat i ng o f hogge ts i s p rac t i s ed , mu l t i p l e cyc l e s a l l ow r e c or d i ng o f t he r e turns t o s e r v i c e . The measurement o f ovu l a t i on r a t e , i n i nd i r e c t s e l e c t i on f o r f e cund i ty ( Hu l l and Hann i ng , 1 9 8 0 ) , by l a pa r o s copy i s a l s o f ac i l i tated by mea s u r eme n t s a t c ons e cut i ve o e s t r us e s . A l th ough the number o f o e s t r us e s r e corded i n th i s s tudy r anged f r om 1 t o 6 , the yea r o f data c o l l e c t i on was t he o n l y f actor c on t r o l l i ng s i gn i f i cant var i a t i on . S e l ec t i on l i ne e f f e cts we r e s ugge s te d by the data , a s FW s he e p had mor e cyc l e s and d i s p l ayed o e s tr us over a l onge r p e r i od t ha n C s he e p , but t h i s e f fe c t was s i gn i f i cant o n l y a t t he 1 0 % l e ve l . 7 . 4 . 4 Re lat i onsh ip t o o t h e r pr oduct i ve charact e r s Al though tentat i ve ly s uppor t i ng the r es u l ts o f Montgome r y a nd Hawk e r ( 1 9 8 7 ) , n o c onc l us i ons can b e drawn about t h e r e l a t i onsh i ps betwe e n w i n t e r wo o l growth , ovu la t i o n r a t e o r l e ngth o f t h e bre ed i ng s e a s o n i n FW and C she e p f r om these data . Both w i nte r woo l gr owth a nd hogge t f l e e c e we i ght we r e unr e lated t o r e pr oduct i ve c haracte r i st i c s i n t h e h ogg e t s s tud i ed . The p oss i b i l i ty t hat the se factors may be r e l a ted 1 4 6 i n ad u l t s he e p i s not d i s c r ed i te d . Ewe hoggets d i f fe r f r om adu l t s i n many ways wh i ch may d i s gu i s e r e la t i ons h i ps be twe e n t he s e tra i ts . F i r s t , t h e e nd oc r i ne s ystem o f yo ung s h e e p i s e x p e r i e nc i ng photoper i od i c cues f or the f i r s t t i me . S e c o nd ly , e ne rge t i c d ema nd s f o r body gr owth may i n f l ue nc e woo l gr owth and r eproduc t i ve pa tte rns . O n the bas i s o f ewe s prese n t a t l amb i ng , the h i ghe r t w i n n i ng r a t e o f FW s h e ep appear e d t o be re lated t o t h e h i ghe r p r opor t i on o f FW ewe s wh i c h we r e c yc l i c a s hoggets . Lamb i ng data f or 1 9 8 5 -born s he e p we r e n o t ava i l a b l e but s h o u ld be e xami ned t o augme nt the 1 9 8 4 -bor n da ta . The mea n two - to o th lamb i ng pe r f o rma n c e o f th i s f l oc k has be e n h i s t o r i ca l l y l ow ( W i c k ham, pe r s . c o mm . ) and i s p o s s i b ly r e l a t ed t o l ow two - t oo t h l i ve we i ghts . The adver s e gra z i ng c o nd i t i o ns o f la t e -autumn a nd w i n t e r o f 1 9 8 6 , a s d i s cu s s ed e a r l i e r may have pr oved e s pe c i a l l y ha rd on 1 9 8 4 - b o r n lamb i ng two - tooths . 7 . 5 CONCLUS I ONS S e l e ct i on f o r h i gh hogget gr easy f l e e c e we i ght appears t o have i nc r ea s ed t h e pe rcentage o f e we h ogge ts a t ta i n i ng puber ty i n t he i r f i r s t autumn . Th i s 2 0 - 2 5% i ncrease has n o t be e n d ue t o l a r g e d i f f e r ences i n a u t umn l i vewe i gh t , a s s e l e c t i on l i ne d i f f e r e nces ( l kg ) a t t a i n s i gn i f i ca nce o n ly by e a r ly J une , wh i c h i s la t e r than the p ea k o f o es tr ous a c t i v i ty i n e we hoggets . I t i s l i k e ly t hat l i vewe i gh t - r e pr od uc t i on re lat i onsh i ps have be e n a l t e re d i n the two f l o c k s , a s o e s t r o us and anoestrous C hogge t s d i d n o t d i f f e r i n l i vewe i ght wh i l e o e str ous FW hogge ts we r e appr o x imate ly 2 kg heav i e r tha? a n o estr ous FW ewe s . The s ugge s t i on has b e en made t hat FW and C s h e ep may r e s pond d i f f e r e n t ly to pho t ope r i od i c cues o r that the i nt e rac t i on o f photoper i od a nd l i ve we i ght " tr i gger s " may be 1 4 7 d i f f e r e nt i n the two l i n es . The age o f FW o r C s h e e p a t f i r s t o e s t r us was una l t e r ed by s e l e c t i on as was the mea n date o f f i r s t o e s t r us , t h ese va l u e s be i ng appr o x i mate , d u e t o t he f or t n i gh t l y r e c ord i ng adopted i n the s tudy . I nc r eased l e ngth o f the b r e ed i ng s e a s on i n FW e we s was s ugge st ed ( p < 0 . 1 0 ) by t h e data , b u t may b e r e lated t o s i gn i f i ca n t l y g r eate r l i ve we i ght dur i ng l a t e autumn . The r e p r oduc t i ve p e r f o rmanc e o f 1 9 8 4 - and 1 9 8 5 - b o r n l ambs s hou ld be f o l l owed th r o ughout the i r l i fe t ime a nd r e la ted t o t h e i nc id e nce o f hogget o e s tr ous . Fur th e r s tudy o f r e p r oduct i ve pe r f o r mance , a s r e lated t o ovu la t i on r a te and a u tumn l i vewe i ght , i s wa r ra nted i n t h i s f l oc k . The l i f e t i me l amb i ng pe r f o rma nc e o f e we s s ho u l d a l s o be r e -a s s e s s ed s o a s t o d i sc e r n be twe e n t h e c omb i ned e f f e c t s o f f e r t i l i ty and f e cund i ty on the 3 0% advan tage o f FW e we s in l i f e t ime pe r f ormance f or n umbe r o f l ambs born o r r e a r ed . 1 50 S TAPLE S TRENGTH OF FW AND C HOGGET WOOL AND I TS RELAT I ONS H I ? TO THE SEASONAL ?ATTERN OF HOGGET WOOL GROWTH AND S TRENGTH OF ADULT WOOL 8 . 1 I nt r od uc t i on a nd r e v i ew o f l i te rature 8 . 1 . 1 Econom i c i mpo rtance I nt e r e s t in s ta p l e s t r e ngth a s a p r oduc t i ve cha r a c te r i s t i c s h ou ld u l t i ma t e l y r e late t o t he p r ocess i ng per f or mance a nd ot wool mar k e t va l u?. ?hys i ca l cha ra c te r i s t i cs s uch as l e ng th a nd d i ame t e r w i l l a l s o a f f e ct ma r k e t va l ue a nd wi l l i nt e ract w i th s t a p l e s t r e ngth . A lt hough H e nde r s on ( 1 9 5 5 ) , Ross ( 1 9 6 0 ) and B i gham et a l . ( 1 9 8 3 ) have i d ent i f i ed f le e ce uns o undnes s a nd i ts r e lated d e f e c ts a s a ma j o r f au l t o f N e w Z e a l a nd woo l , t he r e has be e n l i t t l e d i r e ct e v i d e nce o n t h e i mp o r tance o f s t ap l e s t r e ngth i n d e t e rmi n i ng l o t p r i ce . R o s s ( 1 9 8 2 ) s ugge s t ed that t e nde r wo o l s a nd the i r a s s oc i a t e d f a u l t s , s uc h as c o t t i ng and d i s c o l ourat i on , r e s u l t ed i n a f i na nc i a l l os s t o N ew Z e a l and woo l pr oduc e r s o f $ 5 0m - $ l O O m annua l l y . The s e f i gu r e s r e pr e s e nt 5 - 1 0% o f t h e va l ue o f t h e na t i ona l c l i p . H owe ve r , t h e r e a r e no r e l i a b l e s ta t i s t i ca l a na lys e s o f pr i ce s o f Romney- type woo l s d e sc r i bed a s s ound o r t e nde r i nd i ca t i ng that p r i ce d i f f e r e nt i a ls as l a r ge as the $ 0 . 1 4 - $ 0 . 2 7 pe r k g imp l i ed a b ove a pp l y t o the e nt i r e na t i ona l c l i p . Accord i ng t o f i g u r e s pub l i s hed i n t h e N . Z . W . B . S ta t i s t i ca l Handbook ( 1 9 8 5/ 8 6 ) 2 8 , 5 8 7 t o nnes o f wo o l was c lass i f i ed a s t e nd e r o r c o t ted . T h e ma j o r i ty o f th i s woo l was i n the Romc r o s s 3 3 - 3 7?m range and r epr e s e nted 1 1 % o f the pr oduct i on i n t h i s c a t ego ry . Us i ng ave rage pr i c e s f o r the a bove c la s s e s , a l s o pub l i shed i n the N . Z . W . B . Handboo k , a d i s c ount o f about $ 7m a ppea r s t o have been i nc u r r ed . Eve n i f a tota l c os t t o N e w Z e a l and o f $ 1 0 m annua l ly was r e lated t o t ende r wo o l , f l e e c e t ende r ness wou ld s t i l l be c ons idered a ma j o r wo o l f a u l t . 1 5 1 8 . 1 . 2 P r o c e s s i ng s ign i f i cance The pr o ce s s i ng s i gn i f i cance o f s t a p l e s t r e ngth has been s tud i e d e x tens i ve ly i n Aus t ra l i a n f i ne woo l s ( Doug las , 1 9 8 4 ; TEAM , 1 9 8 5 ) a nd i n New Z e a la nd Romc r oss woo l s ( Ro s s e t a l . , 1 9 6 1 ; Bra t t , 1 9 6 5 ; R o ss a nd Me i k l e , 1 9 8 5 ) . Man u f a c t u r e r s a r e c oncerned w i t h t h e f i br e d iame t e r a nd l e ng th o f woo l as they pa r t l y d e t e rmi ne i ts us e s a nd va l ue ( Ro s s , 1 9 6 0 ; 1 9 8 2 ) . At h i ghe r f i br e d i ame ters the l e ngth o f f i b r e s p r e s e n t i n carded s l i ve r s pr i ma r i l y dete rmi ne s va l ue . H i gh s t r e ngth yarns , c ha r a c t e r i zed by l onger mea n f i br e l e ng t h , a r e c e r ta i n l y pre f e r a b l e i n modern h i gh s pe e d pr o ce s s i ng mach i ne r y . F i br e l e ng th a f te r card i ng i s a f u nc t i on o f the l e ngth and s t r e ng t h o f greasy woo l , the d e g r e e o f f i br e e ntangl ement be f o r e card i ng , the pos i t i on o f a ny t e nd e r r eg i on i n the s ta p l e a nd the cond i t i ons o f t h e card i ng pr ocess ( Ge e , 1 9 7 8 ; Wo od , 1 9 8 4 ) . The l e ngth a nd s t r e ngth o f g r easy wo o l a nd the pos i t i on o f br e a k i n t h e s t ap l e w i l l have t h e g r e a t e s t e f f ects o n f i br e l e ng th a f t e r card i ng . A b reak near the butt o r t i p o f t h e s t a p l e w i l l r educe f i br e l e ngth i n t h e t o p and i nc r ease no i l a ge a s s h o r t f i bres a r e removed i n c omb i ng . A b r eak near t h e c e n t r e o f the s ta p l e may n o t i nc r ease no i lage i f the r ema i n i ng ha lves o f the b r ok e n f i br e s are o f s u f f i c i e n t l e ngth b u t t h e r e may be a ma j or d e c r ease i n mean f i br e l e ngth . An i nc r ease i n no i l age r ed uc e s t op y i e ld wh i l e a d e c r e a s e i n f i br e l e ngth i n the t o p r ed uces i t s subs equent pr oce s s i ng pe r f o rmance . The r e l a t i ve e co n om i c i mpor tance o f t h e s e t wo f actors d epends o n the pr opor t i on o f uns ound f i b r e s a nd the l e ngth o f f i br es be f o re card i ng ( Doug las , 1 9 8 4 b ) . F i br e l e ngth a f t e r card i ng has a mo r e s i gn i f i cant e f f e c t o n s p i nn i ng pe r f ormance and ya rn s t r e ngth o f wo rsted and s e mi ? wor s t ed t ha n woo l l e n- spun yar ns . A l though t ops o f h i gh un i f o rm l e ngth may reduce wo rsted proce s s i ng pe r f orma nc e 1 5 2 t h e s e u n i f o rm l o ts a r e ne ve r ach i e ved u n l e s s wo o l s a r e s or t e d on both l e ngth and s t r e ngth pr i or t o card i ng ( Bratt , 1 9 6 5 ) . Tops o f s h o r te r mea n f i bre l e ng th have l ower s p i n n i ng pe r f orma nc e a nd u l t i mate yarn/ fabr i c s t r e ngth ( Ro s s et a l . , 1 9 6 1 ; Bra t t et a l . , 1 9 6 4 ) . The e f f e c t o f s t a p l e break o n p r o ce s s i ng pe r f ormanc e ( t o p y i e ld a nd s tr e ngth ) i s l i k e ly to be mos t s eve r e whe n the b reak is 2 5% t o 4 0% a l ong the l ength o f t he s tap l e ( Bratt e t a l . , 1 9 6 4 ; W i c k ham, 1 9 6 8 ) . 8 . 1 . 3 Ca uses o f po o r s t r e ngth A mar k e d s eas ona l r hythm o f woo l prod uc t i on e x i s ts in l o ng? woo l l ed breeds o f s h e ep i n New Z ea land . Th i s r hythm i s character i zed by r e d uc t i ons i n the d i ame t e r , c r oss s e c t i ona l a r e a , l e ngth and s ubseque n t we i ght o f f i br e s g r own by s h e ep d ur i ng wi nter months . Eve n whe n nutr i t i on is he ld c onstant t hr oughout the year wo o l g r owth ( g/d ) i s two to t en t i me s g r eate r i n s umme r than i n w i nter months ( Ross , 1 9 6 2 , 19 6 5 ; Ge enty e t a l . , 1 9 8 4 ) . Th i s s eas ona l i ty i s o f c e n t ra l i mportance t o s ta p l e s t r e ngth a s i nd i v i d ua l wo o l f i bres t e nd t o br eak a t t h e i r nar r owe s t po i nt ( F i tzge r a l d et a l . 1 9 8 4 ) . Even s o , Orwi n e t a l . ( 1 9 8 0 , 1 9 8 5 ) c onc l uded tha t the e xa c t l oca t i on o f the b reak may be d i f f i c u l t to p r ed i c t . Month ly d iame t e r measureme n ts may no t , h oweve r , be adequa te i n i de nt i fyi ng s h o r t pe r i ods of r e s t r i c t ed f i br e gr owt h wh i c h have s e r i ous e f f e c t s o n s t a p l e s t r e ngth . The s e s h o r t p e r i ods o f s e ve r e woo l gr owth check can cause o ther wi s e s u pe r i or woo l pr oduce rs t o have f l e e c e s o f l o w t e ns i l e s tr e ngth ( Ross , 1 9 6 5 ) . H oggets have l e s s va r i at i on i n month ly mean f i br e d i ame t e r t h r o ughou t the year tha n ad u l t e we s ( B i gham e t a l . , 1 9 7 8Q). The l ower i nc i d e nc e o f f l e e c e t enderness in hogge t woo l i s a l s o due t o d i f f e r e nces i n ewe and hogge t f eed i ng l eve l s o v e r wi nter a nd the absence o f pr egnancy and l actat i on wh i c h p lace add i t i ona l dema nds on the s upp ly o f n u t r i en ts 1 5 3 f o r wo o l g r owt h t o the e we s . M i n i mum f i b re d i amet e r may n o t be t he o n ly component o f f i br e s t r e ngth . Orwi n e t a l . ( 1 9 8 0 ; 1 9 8 5 ) , Ca r na by ( 1 9 8 4 ) a nd F i t zgera l d ( 1 9 8 4 ) have d emonstrated d i f f e r e nc e s i n i n tr i ns i c s t r e ngth ( l oad/a r e a ) be twe e n f i bres a nd be twe e n s h e e p wh i ch may r e l a t e t o c o r t e x c ompos i t i on o r pr o t e i n p r o f i l e s w i t h i n f i br e s . T e nde r ne s s i n un i f o rml y g r ow i ng wo o l can a l s o ar i s e f r om damage t o t he i nterce l l u la r c eme n t o f woo l f i br e s caused by bac te r i a l i nvas i o n o f t h e s k i n s ur f ac e dur i ng mo i s t , wa rm c o nd i t i o ns ( Rober t s e t a l . , 1 9 6 0 ) . I n e xtr eme cas e s , c o ppe r d e f i c i e ncy can l e ad t o t h e pr oduct i on o f s t ra i gh t wo o l o f ve r y l ow t ens i l e s t r e ngth c ommo n l y k no wn a s ' s t e e l y woo l ' ( He nd e r s o n , 1 9 6 8 ) . 8 . 1 . 4 Measureme nt o f s tap l e s t r e ngth The s t r e ngth o f i nd i v i d ua l s ta p l e s ha s , h i s t or i ca l ly , be e n e s t i ma t ed by e i th e r t he " r i ng '' o f the s tap l e a s i t i s f l i ck e d b e twe e n the f i nge r s , o r t he hand -pu l l r e qu i r ed t o br e a k i t . These t wo s u b j e c t i ve t e s t s can be grea t ly a f f e c ted by the f o r c e e xe r ted by i nd i v idua l a ppra i s e r s , t he t h i ck ne s s o f the s t a p l e s e l e c t ed a nd the pos i t i on o f wea k ne s s i n the s t ap l e ( Rob e r ts e t a l . , 1 9 6 0 ; R o t t enbury , 1 9 7 9 ) . I f b r eak i s t o be c ons i d e r e d a n i mpor tant woo l f a u l t t he n a ny l o ng t e rm r e s earch p rogramme wh i c h a i ms t o r educe t h e i nc i d e nce o f br ea k i n N ew Z e a l and woo l s hould be bas e d o n mor e o b j e c t i ve a nd r e peata b l e mea su r e s o f s ta p l e s t r e n gt h . R o s s ( 1 9 6 0 ; 1 9 6 la ) , H euer ( 1 9 7 9 ) , a nd Doug l a s ( 1 9 8 4a ) have o u t l i ned a va r i e ty o f o b j e c t i ve t e s ts f o r s ta p l e s t r e ngt h . Many a r e based o n the f or c e , i n N ewt ons , r e q u i r ed t o br e a k t he s ta p l e re lat ive t o the s ta p l e ' s l i near d e ns i ty , i n k i l ot e x . The s e me thods r e q u i r e t h e sta p l e t o b e he l d be twe e n o ne f i xed a nd one mova b l e j aw . The sta p l e i s t he n e xt e nded under f orce unt i l mos t o r a l l o f the i nt e r ve n i ng 1 5 4 f i br e s a r e bro k e n . The va l ue s o f s ta p l e s t r e ngth obta i ne d b y var i ous r e s ea rch e r s wi l l va ry due t o mac h i ne f a c to rs s uc h as t he t e st l e ng th be twe e n t h e j aws , t h e rate o f s t ap l e e xt e ns i on and the j a w des i gn . Most o f t h e s e f a c t o r s a r e r e lated t o t he type o f e q u i pme nt used ( Hueur , 1 9 7 9 ) . I r r e s pe c t i ve o f t h e me thod us ed , stap l e s w i t h i n a f le e c e wi l l va ry i n s t r e ngth d u e t o the we ight/dens i ty o f t e s t e d s tap l e s , t h e c on f i gura t i on o f t h e s t a p l e be twe e n t he j a ws a nd the e f f e c ts o f body pos i t i on o n s ta p l e wea ther i ng a nd wo o l gr owt h characte r i s t i cs ( Ross , 1 9 6 0 ; 1 9 6 1a , b ; 1 9 8 2 ; Ross and Me i k l e , 1 9 8 5 ) . The r e p o r t ed c o r r e l a t i ons be t we e n s ub j e c t i ve and ob j e c t i ve measures o f s ta p l e s tr e ngt h have ranged f r om 0 . 6 5 t o 0 . 9 0 ( Ross , 1 9 6 0 ; R o t t enbury , 1 9 7 9 ) ; h oweve r , ma ny s u b j e c t i ve t e sts a r e una b l e t o d i s t i ngu i s h b e twe e n a w ide r ange o f s t r e ngths whe n s t a p l e s t r e ngth i s a bove 3 5 o r 4 0 N/k t e x ( Roberts e t a l . , 1 9 6 0 : R o tte nbury , 1 9 7 9 ) a nd sta p l e s i z e i s mor e c r i t i ca l t o s t r e ngth a s s essment . The a b i l i ty t o d i s t i ngu i s h , not o n ly betwe e n she e p w i t h s upe r i or o r i n f e r i or s t ap l e s t r e ngth b u t a l s o , t o d i s t i ngu i sh accurate ly be twe e n s h e ep o f i nt e rmed i a t e s ta p l e s tr e ngth may be i mportant i n s h e e p i mpr ovement pr ogrammes . 8 . 1 . 5 I mpr oveme nt o f s tapl e s tr e ngt h Al t hough i t i s p os s i b l e t o i mpr ove s t ap l e s t r e ngth by a l t er i ng t he pa tte r n o f f e ed i ntake thr o ughout the yea r , th i s pra c t i ce d o e s n o t c ons t i tute a n e c onom i c s o l ut i on . Hawk e r a nd Cr os b i e ( 1 9 8 5 ) we r e a b l e to v i r t ua l ly e l i m i na t e the s easona l pa t t e r n o f wo o l gr owt h by f e ed i ng a h i gh p la ne o f nutr i t i o n ove r w i n t e r f o l l owed by a l ow p lane ove r summer . I n another e xper i ment Hawk er ( 1 9 8 5? obta i ned a 7 4 % i ncrease i n wo o l gr owth and a 2 4 % i nc r ease i n s ta p l e s t r e ngth thr ough a 1 5 0% i nc r ease i n f e e d i ng : eve l ove r a n 8 wee k w i nter pe r i od . The s e r e g i me s , a l though i n t e r e s t i ng f r om a r e search s tandpo i nt , wou ld be impract i ca l o n - f a rm f o r a number o f r eas ons : 1 5 5 1 ) Feed r e s ources u nd e r gra z i ng c ond i t i ons a r e g r ea t e s t i n s pr i ng a nd a u tumn a nd l o we s t ove r wi nter ( de p e nd i ng o n wea t h e r a nd l oca t i on ) . 2 ) To max i m i s e woo l and l amb pr oduct i on e we s s h o u l d be we l l f ed ove r s umme r -aut umn . 3 ) The e f f i c i e ncy o f woo l g r owth a nd i t s r e s po n s i ve ne s s t o t he p lane o f nutr i t i o n a r e a t l east tw ice a s g r e a t i n s umme r a s they a r e i n w i n t e r ( Sumner , 1 9 7 9 ; Ge e nty e t a l . , 1 9 8 4 ; Hawk e r e t a l . , 1 9 8 4 ) . 4 ) W i nter f e ed i s b e s t u s ed f or the br eed i ng e we s . The pos i t i on o f t e nd e r ne s s i n the s ta p l e i s a f f e c te d by the r e la t i onsh i p b e twe e n shear i ng date and the t ime o f m i n i mum woo l g r owt h ( Ross , 1 9 6 1a , b ) . I n adu l t e wes , the mos t d i r e c t way t o i mpr ove t h e s t r e ngth o f mar k e ted f l eece wo o l wou l d be to s h ear pr i o r t o lamb i ng whe n woo l growth and f i br e d i ame t e r a r e a t t he i r m i n i mum . Th i s may not be p ract i ca l f o r a l l manageme nt s i tua t i ons a s shea r i ng i n l a t e w i n t e r i nc r e a s e s f e ed d emand s a t a t ime o f l imi ted pas tur e gr owt h a nd i ncreases t he r i s k o f p os t -s hear i ng lamb and e we l os s e s ( S umner , 1 9 8 4 ; 1 9 8 6 ) . G i ve n tha t manageme nt prac t i ce s a r e o n ly a temporary s o l u t i on t o impr o v i ng s tap l e s t r engt h , much d i scuss i on has r e c e nt ly tak e n p lace i n New Z ea land on the r o l e o f s ta p l e s t r e ngth i n s he e p br e ed i ng p o l i c i e s ( Rae , 19 8 2 ; R o s s e t a l . , 1 9 8 2 ; B i gham e t a l . , 1 9 8 3 ; Wi c k ham and McP h e r s o n , 1 9 8 5 ) . The i nc l us i on o f s t a p l e s t r e ngth as a s e l ec t i on c r i t e r i o n i n s he e p impr oveme nt programmes ( r a ther t han a s a c ommo n ly accepted s e l e ct i on o b j e c t i ve ) r e q u i r e s k n owledge 1 5 6 o f i t s ge ne t i c and phe notyp i c r e la t i o ns h i ps to o the r p r od uc t i ve c ha racte r s ( wi t h i n age ) a nd t o s t ap l e s t r ength a nd f l e e c e t ra i ts ove r the s he e p ' s l i f e t i me . The h e r i ta b i l i ty o f var i ous meas u r e s o f s t a p l e s t r e ngth should a l s o be a s s e s s ed . I f a pos i t i ve ge ne t i c c or r e la t i on e x i s ts b e twe e n f le e c e we ight a nd s ta p l e s t r e ng th t hen c o r r e l a ted r e sponses i n s ta p l e s t r e ngth s h o u ld accompany s e l e c t i on f or f l e e c ewe igh t . As s t ap l e s tr e ngth mea su r eme nt i s both t ed i ous a nd e xpe ns ive i nd i r e c t s e l e c t i on f o r s t ap l e s tr engt h , e i t he r t h r ough f l ee c ewe ight o r a s s oc i ated wo o l g r o wt h c ha r a c t e r i s t i cs , may o bv ia t e the n eed t o t e s t s ta p l e s t r e ng th o n a w idespread bas i s . He r i ta b i l i ty e s t imates f o r s t ap l e s t r e ngth have b e en mod e r a t e t o h i gh ( 0 . 2 - 0 . 6 ) ( B i gham e t a l . , 1 9 8 3 ; B i gham 1 9 8 4 ) s ugg es t i ng that s tap l e s t r e ngth s h o u ld r e s pond to d i r e c t s e l e c t i on . H oweve r , the c o s t s o f measureme nt c ou ld p oss i b ly e xc e e d the be ne f i ts f r om s e l e c t i on . Chopra ( 1 9 7 9 ) p r oduced e s t i mates o f the he r i tab i l i ty o f hand - pu l l grade in Romney hoggets rang i ng f r om 0 . 0 to 0 . 2 2 . P os i t i ve g e ne t i c cor r e lat i ons b e twe e n s t ap l e s tr e ngth and g r easy f l e e ce we i ght o f 0 . 3 have be e n r e p o r ted by B i gham ( 1 9 8 4 ) wh i l e Chopra ( 1 9 7 9 ) ca l c u lated a gene t i c cor r e la t i on o f 0 . 7 4 be t we e n hand -pu l l grade a nd f le e c ewe i ght . G i ven he r i ta b i l i t i e s o f 0 . 3 a nd 0 . 4 f o r gr easy f l e e c ewe i ght and s t ap l e s t r e ngth r e s pe c t ive ly , a nd ge ne t i c c o r r e lat i ons o f 0 . 3 t o 0 . 7 , i nd i r e c t s e l e c t i on f or s t ap l e s t r ength wou ld be 2 5% t o 6 0% a s e f f i c i e n t as d i r e ct s e l e c t i on . Based on s e l e c t i on p r a c t i ces i n the Mass ey Un i ve r s i ty PT f l e e cewe i gh t s e l e c t i on f l ock ( B l a i r , 19 8 6 ) , t h e pa rame t e r s a bove s hou ld r e s u l t i n c o r r e lated r esponses o f 1 . 7 N/k t ex o r 0 . 2 un i t s o f ha nd -pu l l grade pe r generat i on . The e f f e c t i ve ne s s o f any s ta p l e s t r e ngth s e l e c t i on pr ogramme i n ra i s i ng the l eve l o f s t r e ngth i n the e n t i r e Romc r oss c l i p may a l s o d epend o n the gene t i c a nd phe notyp i c 1 5 7 c o r r e l a t i ons be twe e n hogget a nd ad u l t s tap l e s t r e ngth . The s e c o r r e lat i ons may be i n f l ue nced by the r e l a t i ve s hear i ng dates at b o t h age s . S t r e ngth o f pr e - lamb s h o r n woo l s c o u ld poss i b l y r e s u l t mor e f r om d i f f e r ences i n ave rage f i br e prope r t i e s than o n d i f f e r e nces i n w i n t e r woo l g r owt h . The c o r r e la t i on be t we e n max i mum a nd mi n i mum s ta p l e s t r e ngth i s l ow ( . 2 6 ) a nd o f va ry i ng s i gn i f icance ( Ro s s , 1 9 6 5 ; R o ss a nd Me i k l e , 1 9 8 5 ) . Ave rage w i n t e r wo o l g r owth may c ontr i bute l e s s to s ta p l e s t r ength in pos t - lamb s ho r n wo o l s than t h e pr e s e nc e o f , o r r e s ponse t o , s h o r t t e rm nutr i t i o na l o r phys i o l og i ca l s t r e s s . 8 . 1 . 6 Obj ect i ve s o f t he c ur r e nt t r i a l ( 1 ) t o e xami ne 'tn stqple str-e.ng-fh t he c o r r e l a ted r e sponsesA to s e l e c t i on f or h i gh greasy f l e e c ewe i gh t i n Mass ey Un i vers i ty ' s R omne y f l e e c ewe i ght s e l e c t i on f l ock ( B l a i r e t a l . , 1 9 8 5 ) ; ( 2 ) t o quant i fy the i mpor tance o f s ources o f var i a t i on ?l h stqple st,-qr:Jfh s uc h as s he e p , s i r e a nd s e l ec t i on l i ne ; ( 3 ) t o r e l a t e t he o b j e c t i ve measures o f s tap l e s tr e ngth i n hogge t f l e e c e woo l t o t he i r k nown month l y pa t t e r ns o f woo l growth ; ( 4 ) to d eterm i n e the r e lat i onsh i p be tween hand - pu l l grade and s ta p l e s t r e ngth ; ( 5 ) t o d eterm i n e the r e l a t i onsh i p be tween e we h o gge t a nd two - tooth s ta p l e s t r e ngth . 1 5 8 8 . 2 MATER I ALS AND METHODS 8 . 2 . 1 E xpe r i me nta l plan S ta p l e s f r om a mids ide samp l e o f the hogge t f l ee c e f r om 1 9 8 4 -b o r n rams a nd e we s , o f t h e f l e e c ewe i ght -s e l ect ed ( FW ) a nd c o n tr o l ( C ) l i ne s , we r e t e s ted f or max i mum l oad o n a Houns f i e ld t e n s ome t e r . The s e s he e p had c omp l e t e r e c ords o n month l y woo l growth ( Chapt e r 5 ) . The s ta p les used had be e n dye - banded month ly and we r e r e moved o n 1 7 October 1 9 8 5 j us t pr i o r t o hogge t shear i ng . Re p laceme nt FW and C e we s pre s e nt i n t h e f l oc k as two-t o o th e we s i n 1 9 8 6 wer e mids i d e samp l ed a t e we s hear i ng on 2 1 Oc t ob e r 1 9 8 6 . S ta p l e s f r om t h i s m ids i d e samp l e wer e a l s o t e s t e d f or max i mum l oad . The n umbe rs o f FW and C e we and ram hogge ts t e st ed a r e g i ve n i n Tab l e 8 . 1 a s are the numb e r s o f F W a nd C ewes r e -t e s t ed a s two - t ooths . 8 . 2 . 2 Equ ipme nt used A H o uns f i e ld t e nsome t e r , o r i g i na l ly e q u i pped wi t h a s pr i ng ? l oaded me rcury manua l r e adout a nd moto r dr i ve un i t , was mod i f i ed t o a l l ow automat i c r e c ord i ng o f the max i mum l oad . The mod i f i ed mac h i ne was s e t up as i l l us trated schema t i ca l ly i n F i gure 8 . 1 . The spr i ng- l oaded sca l e was d i sconnected a nd a n e l e c t r o n i c e xpans i on -ce l l was i ns e r te d be twe e n the f r ame o f t h e mach i ne and the f i xed wo o l c l amp . The e xpans i on -c e l l was c o nnected t o an AG- 3 0 0 d i g i ta l d i s p lay un i t wh i ch trans lated the ana l ogue s i gna l s f r om the e xpans i on- ce l l t o d i g i ta l s i gna l s . The AG- 3 0 0 prov ided a v i s ua l d i s p lay o f the l oad s usta i ned by the s ta p l e as i t was be i ng p u l l e d . An Eps on HX - 2 0 portab l e mi c r o -c omputer r ece i ved l oad measu reme nts f r om the AG- 3 0 0 at the rate of 4 per s e c ond a nd was pr ogrammed to automa t i ca l ly r e cord the max i mum l oad . Sta p l e s we r e pu l l ed by a mot o r -dr i ven sha f t at t he rate o f 5 cm per mi nute s uc h that betwe e n 2 5 0 and 5 0 0 t o ta l l oad measur eme nts we r e r e c e i ved . 1 5 9 8 . 2 . 3 Measureme n t o f s taple s t r e ngth A l l measureme nts we r e ta k e n in a humid i ty c ontr o l l e d l a bora tory ( 2 0 ? 2 ? C , 6 8 ? 2 %RH ) . Te n s t ap l e s f r om the greas y m ids i d e samp l e we r e s e l e cted f or t e s t i ng . Pr i or t o mea s ur i ng the s e s ta p l e s , a n add i t i ona l s t ap l e was b r o k en by hand - pu l l t o d e t e rmi ne the r e g i o n o f break . Butt e nds o f t h e s tap l e s we r e s e c ur e l y c lamped betwe e n the f i xed j aws a nd the s ta p l e t i p was s e cured i n t he mova b l e j aws . S tapl e s we r e pos i t i oned s o tha t the a rea o f break wou l d b e wi th i n t h e 8 c m t e s ted r e g i on . S ta p l e s wer e e x t ended unt i l the l oad d i s p layed o n t h e AG- 3 0 0 had v i s i b ly d ecr eased f r om max i mum and s ta p l e s s h owed e v id e nce o f b reakage . F i br e s f r om betwe en the j aws wer e c u t f r e e a nd we i ghed t o t he near e s t mg . I f f i bre s l i ppage was e v id e nt dur i ng the p u l l t he s t ap l e was r emoved a nd the mea s urements d i scarded . C l ean we i ght o f woo l t e s ted was e s t i ma t ed f r om the c l ean y i e ld o f mi ds ide samp l e s taken a t s hear i ng . Max i mum l oa d was e xpressed i n N/k te x . S ta p l e s tr ength a nd month o f s ta p l e break o f hogget samp l e s we r e a l s o e s t i ma t ed b y hand - pu l l . Hand - pu l l s tr e ngth g rades we r e on a s ca l e o f 1 t o 9 . A s i ng l e va l u e was r e c o rded a f t er 1 t o 4 s ta p l e s we r e b roken by hand . The d escr i pt i on o f t h e s e hand-pu l l grad e s i s g i ve n i n Tab l e 8 . 2 . Month o f b r e a k was d e t e rmi ned by hand -brea k i ng a t l ea s t t h r e e dye -banded stap l e s p e r s h e ep . I n c a s e s whe r e s ta p l e s broke i n a d i f f use a rea the month i n the c e ntre o f t h e break r e g i on was r e c orded . 8 . 2 . 4 S tat i s t i ca l me thods A number o f l i near mod e l s we r e used t o ana lyze s ta p l e s tr e ngth and hand -pu l l grade data . The f i r s t mode l ( 8 . 1 ) i nc l uded i nd i v idua l s ta p l e measurements t o ena b l e the 1 6 0 e s t i ma t i on o f w i th i n - a nd be twe e n - s he e p va r i ance s . Th i s mode l i gn o r ed f i xed e f f e c t s o ther t han s e x and s e l e c t i on l i ne a s i t was thought that c o r r e c t i on factors bas ed on mu l t i pl e r e c ords m i ght n o t n ecessar i ly r e f l e ct c o r r e c t i o n f a c t o r s bas ed o n s he e p mea ns . The s e c ond mode l ( 8 . 2 ) was u s ed t o e s t i mate s i r e a nd e r r or va r i ances f or hand - pu l l g rade , mon th o f b reak a nd s he e p mea n va l ue s f o r s ta p l e s t r e ngt h . Th i s mod e l i nc l uded f i xed e f f e cts wh i ch had b e e n f o und , i n pre l i mi na ry a na lys e s , t o have s i gn i f i ca n t e f f e c ts o n o n e o r mor e o f the t ra i t s s t ud i ed . Mod e l 8 . 3 wa s d e s i gned t o o bta i n l e a s t squa r e s means f o r sta p l e s t r e ng t h a n d woo l gr owth c ha rac te r i s t i cs i n each hand- pu l l grade c la s s in o rd e r t o a s s e s s t h e i r e f f e ct o n sub j e c t i ve s t r e ngth c la ss es . The f i na l mode l ( 8 . 4 ) was used t o e s t i ma t e t he r egress i on o f two - tooth s tap l e s t r e ngth on h ogg e t s t a p l e s t r e ngth a f t e r ad j us tme nt f or two -t oo t h lamb i ng s ta tus . The r epeata b i l i ty a nd h e r i ta b i l i ty o f s tap l e s t r e ngth a c r o s s 1 0 s ta p l e s f r om e a c h s he e p was e s t imated i n the f o l l ow i ng n e s t e d mode l : M od e l 8 . 1 whe r e , y ? ? k ?= = the o b s e rve d s ta p l e s t r e ngth o f t h e mt h s t a p l e f r om t h e l t h s he e p i n e a c h i th s e x , j t h l i n e and j k th s i r e c la s s , J.L = an ove ra l l mea n , t ? = the f i xed e f f e c t o f t h e i t h s e x , l ? = the f i xed e f f e c t o f t he j t h s e l e c t i on l i ne , S ? k = the random e f f e ct o f the k th s i r e w i t h i n each j t h s e l e c t i on l i ne , s h ? ? k ? = the r a ndom e f f e c t o f the l t h she e p o f s e x i w i t h i n each j k t h s i r e s u bc lass , a nd 1 6 1 e ? ? k ?= = th e r a ndom r e s idua l a s s oc i a ted w i t h each mtn s ta p l e f r om the l t h s h e e p i n e ach i t h s e x , j t h l i n e a nd j k t h s i r e c la s s . Var i ance c omponent s f o r r a ndom s i r e a nd s h e ep c omponents we r e o bta i ne d by e quat i ng each mea n squa r e t o i ts e xpecta t i on whe r e : e r r o r var i a nc e ( a 2 e s he e p var ia nc e ( ?? ) = Er r or Mea n S quar e ( EMS ) , = ( S h e ep MS - EMS ) I 1 0 . , s i r e var ia nc e ( S i r e MS - EMS - 1 0 a.? ) ) / 1 5 3 . 0 9 , he r i ta b i l i ty ( h 2 ) = ( r e peatab i l i t y ( R 2 ) = I ) , and S i r e and e r r o r va r i a nces f o r hand -pu l l g rade , mon th o f b r ea k a nd s h e ep mea n s t a p l e s t r e ngth we r e obta i ned f r om t h e f o l l ow i ng mode l : M od e l 8 . 2 whe r e , y? ? k ?=n = t h e o b s e rved s tap l e s t r ength/hand - pu l l grade o r mon t h o f b r eak o f the n t h s h e e p be l ong i ng t o )l = b? = whe r e , x ? ? k ?rnn r ? d ? t k l ? t o t h e rnt h s i r e , l t h s e l e ct i on l i ne , k t h s e x , j t h darn age a nd i t h b i r th rank c l a s se s , o ve ra l l mea n , r e g r e s s i on c oe f f i c i en t o f Y ? ? k ? mn on x ? ? k ?rnn = o bs e r ved i nd i v i dua l b i r t hdate , = f i xed e f f e c t o f the i t h b i r t h r ank c lass , = f i xed e f f e c t o f the j t h age o f darn c lass , = f i xed e f f e c t o f the k t h s e x , = f i xed e f f e c t o f the l t h s e l e ct i on l i ne , 1 6 2 s ?= = random e f f ec t o f the mth s i re w i t h i n e a c h l th s e l e ct i on l i ne , and e ? ? k ?mn = random r es idua l a s s oc ia ted wi th t he i j k l mnt h obs e r va t i on . Equa t i ng e ach mea n square t o i ts e xpecta t i on y i e lded : e r r o r var i ance s i r e va r i ance ? 2 s and h e r i ta b i l i ty ( h 2 ) = Err o r Mea n S quar e ( EMS ) , = ( S i r e MS - EMS ) I 1 5 . 3 0 9 , = ( 4crt ) I ( cr2 s Cor r e lat i ons be twe e n b i r t h date , b i r t h rank , dam age a nd s e x c o r r ected r e s idua l s f or s t a p l e s t r e ngth and woo l gr o wt h c haracte r i s t i cs we r e ca l cu lated w i t h i n s e l e c t i o n l i ne a nd t e s t ed f or homogene i ty a nd p oo l e d , i f h omoge neou? by z ? t rans f ormat i on acc ord i ng t o S te e l e a nd Torr i e ( 1 9 8 0 , p 2 8 2 ) . L e a s t squares means f or s t ap l e s t r e ngth a nd woo l gr owth c haracte r s by hand -pu l l grade c lass we r e obta i ne d f r om the f o l l ow i ng mode l : Mod e l 8 . 3 whe r e , y ? ? k ?mn = an o bs e rva t i on o f s t r e ngth or wo o l gr owth characte r i s t i c on the nth s h e e p o f s e x k , s e l e ct i on l i n e 1 , dam age j a nd b i r t h rank i and hand -pu l l grade k , ? = an ove ra l l mea n , b ? = the r e gr e s s i on c oe f f i c i e nt o f y ? ? k ?=n o n x ? ? k ?mn whe r e , x ? ? k ? mn = an obse rved i nd i v i dua l b i r t hdate , r ? = the f i xed e f f e c t o f the i th b i r thrank c la s s , 1 6 3 d :;j = the f i xed e f f e c t o f the j th age o f dam c l ass , t k = t h e f i xed e f f e c t o f s e x k , 1 ? = the f i xed e f f e c t o f s e l ec t i o n l i ne 1 , hrn = t he f i xed e f f e c t o f hand - pu l l grade m , a nd e J. :;j k ?rnn = the r andom r es i d ua 1 a s s oc i a ted w i th a n o b s e rvat i on on the nth s h e e p o f s e x k , s e l ec t i on l i ne 1 and hand - p u l l grade m . Two -t o o t h and hogget s t ap l e s t r e ngth we r e ana l ys ed a ccord i ng t o the f o l l ow i ng mode l , whe r e l amb i ng s ta tus l =d ry, 2 =s i ng l e a nd 3 =t wi ns : Mode l 8 . 4 whe r e , y J. :;j k = a n observed s ta p l e s t r e ngth o n the k th two - t o o t h e we o f lamb i ng s ta tus i a nd s e lect i on l i ne j , M = a n ove ra l l mea n , p J. = t h e f i xed e f f e c t o f two - t o o t h l amb i ng s tat us , 1 " = t he f i xed e f f e c t o f s e l e ct i on l i ne j , b ? = t h e l i near r eg r es s i o n coe f f i c i e n t o f yJ. :;j k ? o n , X J. :;j k = t he observed h ogget s t a p l e s t r e ngth , and e J. :;j k = the r andom r es i d ua l a s s oc i a t ed w i th t he k th twotoo th ewe o f l amb i ng s ta tus i f r om se l e c t i on l i ne j . 8 . 3 RESULTS 8 . 3 . 1 S our c e s o f var i a t i on i n hand -pu l l grade a nd stapl e s t r e ngth o f hogge t samples 1 6 4 Ne i t h e r hand-p u l l grade ( PULL ) n or s t ap l e s t r e ngth ( STR ) we r e s i gn i f i cant ly a f f ec t ed by b i r t h da te or age o f darn ( F i gure 8 . 3 ) . Hand -pu l l grade d id not d i f f e r b e twe e n s i ng l e - and twi n -born lambs but s ta p l e s t r ength was s i g n i f i cant l y gr e a t e r i n s i n g l e - t han i n twi n - bor n hogget s ( 2 5 . 7 ? 1 . 9 vs . 2 1 . 8 ? 1 . 7 N/ k t e x ) . Ram and e we hogge ts d i d not d i f f e r i n s ta p l e s t r e ngth but hand-pu l l grade was greate r i n e we hogge ts ( 6 . 0 4 ? 0 . 2 0 vs . 5 . 1 5 ? 0 . 2 1 ) . No i n te ract i ons e x i s t ed betwe e n t he f i xed e f f e cts o f s e x , s e l e c t i on l i ne , b i r t h rank o r darn age a nd the r egress i on o f STR o r PULL o n b i r t hdate was h omogen e ou s a c r os s a l l f i xed e f f e c t s . I n o rde r to mor e r ead i ly compa r e s t r e ngth a nd woo l gr o wth var i ab l e s a l l s ubsequent a na lys e s , u n l e s s o therwi s e state d , r e f e r t o data c o r r e c ted f o r the f i xed e f f e c ts a bove . A l t h o ugh darn age and b i r th date d id not s i gn i f i cant l y a f f e c t e i th e r PULL or S TR they we r e i nc l uded i n subs equent a na l ys?s i n orde r t o obta i n s tap l e s t r e ngth measu r e s c o r r e cted f o r t he same e f f e c ts as many o f t h e wo o l growt h character i s t i cs . As s hown i n Tab l e 8 . 3 s t a p l e s t r e ngth was s i gn i f i ca n t ly g r e a t e r i n FW t h a n i n C hogge ts ( . 0 1 < p < . 0 5 , R 2 = 1 1 . 5% ) but d i f f erences i n hand - pu l l grade we r e not c l ear ly s i gn i f i cant ( . 0 5 < p < . 1 0 , R 2 = 1 7 . 7 % ) . S e l ect i on l i ne a ccounted f o r 4 . 5% and 1 . 9 % o f the t ota l sums o f s quares f or s tap le s t r e ngth a nd hand -pul l grade , r e spe c t i ve ly . The d i s t r i but i ons o f s t ap l e s t r e ngth a nd hand -pu l l grade in FW a nd C sheep a r e g i ve n i n F i gures 8 . 2 ( a , b ) . The e f f e ct o f s i r e ( w i t h i n l i ne ) was s i gn i f i cant f or stap l e s t r e ngth ( 0 . 0 1 < p < 0 . 0 5 ) a nd hand - pu l l grad e ( 0 . 0 1 < p < 0 . 0 5 ) . The pr opor t i ons o f t he t ota l s ums o f s qua r e s 1 6 5 accounted f o r by f i xed e f f e c t s , s e l ect i on l i ne a nd s i r e w i th i n s e l e c t i on l i n e a r e s h o wn i n F i gures 8 . 3 ( a , b ) a l o ng w i t h the r e l e vant s ums o f s quar e s . T h e he r i ta b i l i ty o f s t a p l e s t r e ngth was 0 . 4 7 ? 0 . 3 4 f r om s i r e a nd e r r o r var i a n c e s respecfive/!) o f 1 3 . 5 7 9 8 ( N/ k t e x ) 2 a nd 1 0 2 . 3 3 9 8 ( N/ k te x ) ? . The h e r i ta b i l i ty o f hand - pu l l grade was 0 . 3 8 ? 0 . 3 0 f r om s i r e a nd re?clive/l/ e r r or var i ances o f 0 . 1 4 0 4 ( c l a s s e s ) 2 a nd 1 . 3 4 4 8 ( c l a s s e s ) A . J The r e la t i ve ly l a rge s t andard e r r or s a r e l i k e l y due t o t h e s ma l l n umbe r o f s i r e s r e p r e s e nted i n t h e da ta . Us i ng s t a p l e s t r e ngths f r om a l l 1 0 measured s t a p l e s p e r s h e ep y i e lded var iance e s t i ma t e s o f 1 0 5 . 7 3 ( N/ k e xt ) 2 b e twe e n - a nd 3 0 . 3 2 ( N/k t e x t ) 2 w i t h i n- she e p t o g i ve a n a c r o s s s ta p l e r e peata b i l i ty o f 7 7 . 7 % . S i r e var i ance i n t h i s mode l , wh i ch was unc o r r e ct ed f o r f i xed e f f e c t s o the r t han s e x , was 1 0 . 8 9 ( N/ k t e x ) 2 y i e ld i ng a h er i tab i l i ty o f 0 . 3 0 ? 0 . 2 6 . The pr opor t i ons o f t he t ot a l s ums o f s q ua r e s accounted f o r b y s tap l e s w i t h i n s he e p , s he e p , s i r e , s e l e c t i on l i ne a nd s e x i n Mode l 8 . 1 a r e g i ve n i n F i gure 8 . 3 ( c ) a l ong w i t h the r e l e vant s ums o f s quar e s . 8 . 3 . 2 S i r e a nd s e l e c t i on l i ne e f f e c t s on s tapl e s t r e ngth a nd the i r r e la t i o ns h i p to the s e a s o na l pat t e r n o f h ogge t woo l gr owt h . S e l e c t i on l i ne l e a s t squa r e s means ( f r om Mode l 8 . 2 ) f or S TR , PULL a nd t he f l e e c e characte r i s t i cs i nc l ud i ng : W i nter wo o l gr owth t ra i ts : - l owe s t month ly f i b re d i ame t e r ( LFD ) , - l owes t month ly c l ean wo o l gr owth per day ( LCPD ) , - l owe s t month ly l e ngth gr owt h rate pe r da y ( L LPD ) ; Ampl i tude t ra i ts : - amp l i tude o f f i b re d i ame te r ( FDAMP ) , - amp l i tude o f c le a n woo l growth ( CPDAMP ) , - amp l i tude o f l e ng th gr owt h rate ( LPDAMP ) ; 1 6 6 Ave rage woo l gr o wt h t ra i t s : - mean a nnua l f i br e d i ame ter ( MFD ) , - g reasy f l e e c e we i ght ( GFW ) , - c l e a n f l e e ce we i ght ( CFW ) , - s taple l e ng t h ( S L ) ; ' Month o f ' t ra i ts : - month o f s ta p l e break ( MB ) , - month o f l owes t f i br e d i amet e r ( MLFD ) , - month o f l o we s t c l ean woo l g rowth ( ML CPD ) , - month o f l owes t l e ngth gr owt h rate ( MLLPD ) a r e g i ve n i n Tab l e 8 . 3 a l ong w i t h the i r s tandard e r r o r s . I n o rder t o a s s e s s t he contr i but i on o f t h e s e woo l gr o wt h c haracte r i s t i cs t o s e l ect i on l i ne d i f f e r e nces i n s t ap l e s t r ength , t h e s i mp l e c o r r e lat i ons among a l l var i a b l e s we r e f i r s t e xami ned wi t h i n each s e l ect i on l i ne . An uppe r ? d iagona l mat r i x o f p o o l ed ( where homogen e ous ) a nd w i t h i n? l i ne ( wh e r e h e t e r oge ne ous ) c o rre la t i on c oe f f i c i e nts i s pr e s e nted i n Tab l e 8 . 4 . H eter oge ne ous w i t h i n- l i ne c o r r e lat i ons e x i s te d most predomi nant ly i n the var i a b l e s s uch as MB , MLFD , MLCPD and MLLPD . ' month o f ' An e xami nat i o n o f t h e f i rst two r ows o f Tab l e 8 . 4 s h ows that w i nt e r woo l gr o wt h t r a i t s had the h i gh e s t c or r e l a t i ons wi t h s ta p l e s tr e ngth ( 0 . 3 8 t o 0 . 4 2 ) . C o rre la t i ons b e twe e n s t a p l e s t r e ngth and amp l i tude tra i ts wer e o f s i mi lar magn i t ude but o ppos i te s i gn t o those o f wi nter wo o l g r owth tra i ts ( - 0 . 3 4 t o - 0 . 4 4 ) . Ave rage wo o l gr owth tra i ts we r e pos i t i ve ly c o r r e lated t o s ta p l e s t rength ( 0 . 1 9 t o 0 . 2 7 ) . ' Month o f ' t ra i ts , w i t h t h e e xc e pt i on o f MLLPD i n FW s he e p , we r e n ot s i gn i f i cant ly r e l a t ed t o s ta p le s t r engt h . T he c o r r e lat i ons be twe e n PULL a nd woo l gr owth measures we r e ve ry s i mi lar t o those j us t pr e s e nt ed . Cor re lat i ons among woo l g rowth characters have b e e n p resented and d i scussed i n ear l i e r s e c t i ons . 1 6 7 The c o n t r i but i o n o f va r i o us woo l g rowth charac te r i s t i cs t o l i ne d i f f e r e nces i n S TR a nd PULL was a l s o t e s t ed by a na lys i s o f va r i ance us i ng s e que n t i a l s ums o f s qua r e s f r om a mod e l whe r e the c ovar i a t e p r eceded s e l e ct i on l i ne e f f e c ts . Al l d e pe nd e nt a nd i nd e pe ndent va r i a b l e s we r e c o r r ec ted f or a l l f i xed e f f e c t s e xc e pt s e l e c t i on l i ne . T h e a b i l i ty o f t h e c ova r iate t o r e move s e l e c t i o n l i ne d i f f e r e nces i n S TR o r PULL was j udged by the pr oba b i l i ty a s s o c i a t ed wi th the s e l e c t i on l i ne mea n squa r e a nd the mu l t i p l e cor r e la t i on c o e f f i c i ent ( R2 ) o f the mode l . The r e gr e ss i o ns o f S TR o r PULL o n measur e s o f woo l gr owth we r e a l l homoge neous across g enotype s . The r eg r e s s i on c oe f f i c i e nts , R 2 va l ue s , a nd s ubseque n t probab i l i ty a s s oc i ated wi t h s e l ec t i on l i n e e f f e c t s a r e g i v e n i n Tab l e 8 . 5 . As regre ss i on s f o r S TR a nd PULL s h owed s im i lar t r e nd s , o n l y t h e r egr e ss i ons i nvo l v i ng S TR w i l l be pr e s e nt ed he r e . Al l r e gr e s s i o ns o f s ta p l e s t r e ngth o n woo l g rowth charact e r i s t i cs we r e s i gn i f i cant whe n f i t ted pr i or t o or f o l l o w i ng genotype e f f e c ts . P r e -ad j us tme n t for the e f f e c t s o f CFW , GFW, F? SL , LFD , LCPD and LLPD rend e r ed s e l ec t i on l i ne d i f f e r e nces i n s ta p l e s t r e ngth n on - s ign i f i ca n t i nd i ca t i ng t ha t t h e s e t ra i ts c o nt r i buted , e i t h e r d i r e ct ly o r thr ough the i r c o r r e la t i on t o other tra i ts , t o s e l e c t i on l i ne d i f f e r e nces i n s t a p l e s t r e ngth . As m i ght be e xpec ted f r om t he s imp l e c o r r e lat i o n s p r e s e n t ed i n Tab l e 8 . 4 , measur e s o f w i n t e r woo l gr owt h gave the h i gh e s t R 2 va l ue s ( 1 9 % t o 2 1 % ) re l at i ve to 8 % t o 1 2 % f or ave r a ge woo l gr owth t ra i t s . R 2 va l u e s f or t h e r e g r e s s i on o f s ta p l e s tr e ngth o n amp l i t ude t ra i ts ranged f r om 1 6 % t o 2 3 % . I n n o i ns tance d i d amp l i tude t ra i t s remove se l e c t i o n l i ne d i f f e r e nces . Pre -ad j us tme nt f or FDAMP ra ised the s i gn i f i cance of s e l e ct i on l i ne e f f ects . The mon t h o f mi n i mum product i on o r mo nth o f woo l break had n o e f f e c t o n s e l e c t i on l i ne d i f f e r e nces i n s tap l e s t r e ngth . 1 6 8 Month o f s ta p l e break was h i gh l y he r i ta b l e ( 0 . 5 0 ? 0 . 3 2 ) but bore no c l ea r r e la t i on t o s ta p l e s tr e ngth i n e i t her FW or C s h e e p ( Ta b l e 8 . 4 ) . Contr o l s he e p t e nded to have weak e r woo l i f t h e b r eak was c l o s e r t o t he b u tt o f the s t ap l e but t he c o r r e l a t i on was o n ly s i gn i f i c ant a t t he 1 0% l e ve l . I n b o t h C and FW s h e ep the ' mo n t h o f ' var i a b l e s wer e pos i t ive l y c o r r e la ted but re la t i ons h i ps amongs t t he s e va r i a b l e s we r e s t r onger i n C t ha n FW she e p . M o s t n o tab ly , MB was uncor r e lated w i t h MLFD i n FW s h e e p wh i le the c o r r e lat i on i n C s h e e p was 0 . 4 1 I n both FW a nd C s h e e p , l a t e r month o f s ta p l e br e a k was accompan i ed by l owe r mi n i mum f i br e l e ngth gr owt h , h i gh e r amp l i t ude o f l e ng th gr owth , l ower amp l i tude o f f i bre d i ame t e r a nd l owe r average f i br e d i ame te r a nd s ta p l e l e ngt h . The d i s tr i bu t i ons o f FW and C s he e p f or MB , MLF D , MLCPD a nd MLLPD a r e g i ve n i n F i gure 8 . 4 . Cont r o l s he e p d i st r i but i on s f or a l l t ra i ts a nd t h e FW d i s t r i but i on f or M B we r e cha ra c te r i zed by s t rong c e n t ra l t e ndency, t h e mode a nd the mea n be i ng i n c l os e agr e eme n t . D i s t r i but i ons o f FW s he e p f o r MLFD , MLCPD and MLLPD we r e s p l i t w i th the ma j o r i ty o f observa t i ons f a l l i ng i nt o e i t h e r months 5 or 7 . I n Cha pte r 5 , FW hogge ts we re f ound t o r each mi n imum woo l gr owth appr o x i ma t e l y 5 wee k s ear l i e r than C hogge t s . Howe ve r , month o f break was o n l y 2 we e k s ear l i e r i n FW than C h oggets . 8 . 3 . 3 The r e l a t i onsh i p betwe e n hand -pu l l grade and s tapl e s tr e ngth As g i ven i n Tab l e 8 . 4 , t he c o r r e l a t i on be twe e n hand-pu l l grade and s ta p l e s t r ength was 0 . 5 8 s o that 3 4 % o f the va r i a t i on i n measured s tap l e s t r e ngth was accounted f or by va r i a t i on i n s ub j e c t i ve assessme nt . Leas t squares means f o r s ta p l e s t r e ngth and woo l gr owt h c haracte r i s t ics f or each hand -pu l l grade c lass a r e g i ve n in Ta b l e 8 . 6 . Als o s hown in 1 6 9 th i s tab l e are the range o f s tap l e s t r e ngths r e pr e s e nted i n each hand -pu l l grad e a nd the s ta p l e l i near d ens i ty i n k t e x . Mean s ta p l e s t r e ngth i nc r eased w i t h hand - pu l l grade . Mea n d i f f e re nces b e twe e n a l l c la s s e s e xc e pt 5 and 6 , a nd 2 / 3 a nd 4 , we re s i gn i f i ca n t . The var ia t i on i n measured s tr e ngth w i t h i n each c la ss i s i nd i cated by t he r ange . W i th t he e xc e pt i o n o f the l o we s t s t r e ngth c lass , the range i n r ema i n i ng c la s s e s was n ear t o 3 0 N/k te x . Ve r y s im i l a r ranges e x i s ted f or c la s s e s 4 , 5 a nd 6 . Hand -pu l l grade was pos i t i ve l y a s s oc iated w i t h mea n c l ean wo o l growth a nd w inter wo o l g r owth . I nc r eased hand -pu l l grade was a l s o character i zed by a d ecrease i n amp l i tude o f woo l g r owt h . Hand -p u l l grade d i d not appear t o be a f f e c t ed by the average l i near d e ns i ty o f s tap l e s s e l e ct ed or by ' mo nth o f ' va r i ab l e s . 8 . 3 . 4 The r e la t i on s h ip be t we e n e we h ogge t and t wo -t o oth s tapl e s t r e ngth Over the 4 0 e we s mea s ured as hogge ts and aga i n as two - t o ot hs the c o r r e lat i o n be twe e n raw va l ue s o f e we and h ogge t s ta p l e s t r e ngth was 0 . 3 4 . The c o r r e lat i o n was s i gn i f i cant l y h i gher f o r FW ( 0 . 4 3 ) t han C e we s ( 0 . 2 2 ) . Hogge t s tap l e s t r e ngth a l one e xp l a i ned 1 2 % o f t h e var i at i on i n s ubsequent e we s t r ength . An add i t i ona l 3 . 5% was e xp la i ned by s e l e c t i on l i ne e f f e cts . Lamb i ng s ta t us as t wo -t o oths ( d ry , s i ng l e o r twi n ) d i d not s i gn i f i cant ly a f f e c t s ta p l e s t r e ngth i n t h e s e data . Average s t r e ngth was not s i gn i f i cant ly d i f f e r e n t i n FW a nd C two - tooth e we s , the means be i ng 1 2 . 7 ? 3 . 0 N/k t e x a nd 1 0 . 2 ? 1 . 5 N/k t e x , r e spect i ve l y . 1 7 0 Tab l e 8 . 1 Number o f h ogge ts tes ted , and two t oo ths r e - tested f or s tap le s t r e ngth i n the f l e e c ewe i ght -s e l ected ( FW ) and Cont r o l ( C ) l i nes . 1 = = = = = = = = = = = = = = == = = = = = = 1 I I I SELECTI ON L I NE I I I 1 - - - - - - - -- - 1 - - - - - - - - - - - 1 I C I FW I 1 = = = = = = = = = = = = = = = == = = 1 = = = = = = = = = = 1 = = = = = = = = = = = 1 == = = = = = 1 I I I I I I HOGGET : RAMS I 2 7 I 2 8 I 5 5 I I EWES I 2 7 I 4 3 I 7 0 I I I I I I l - - - - - - - - - - - - - - - - - - - l - - - - - - - - - - 1 - - - - - - - - - - - l - - - - - - - l I I I I I I TWO-TOOTH : EWES I 2 0 I 2 0 I 4 0 I I I I I I = = = = = = = = = = = = = = = = = = = = = 1 = = = = = = = = = = 1 = = = = = = = = = = = 1 = = = = = = = 1 I I I I I 5 4 I 7 1 I 1 2 5 I 1 = = = = = = = = = = 1 = = = = = = = = = = = 1 = = = = = = = 1 Tab l e 8 . 2 De sc r i pt i on o f hand -pu l l grad e s f or s ta p l e s oundness 1 Much o f f l eece l ost 2 Ve r y wea k - obv i ous " break " 3 S l ight pu l l t o break 4 Moderate pu l l t o break 5 G ood pu l l to break 6 S l i ght pu l l t o break 1/ 2 s tap l e 7 Good pu l l to break 1/2 s ta p l e 8 Good pu l l t o break 1/4 s tap le 9 S o und ( 1/ 4 sta p l e ) AG - 300 EXPANSION CELL HOUNSFIELD TENSOMETER EPSON HX - 20 Figure 8 . 1 SCHEMATIC REPRESENTATION OF THE HOUNSFIELD TENSOMETER AND LOAD RECORDING EQUIPMENT 1 7 1 Tab l e 8 . 3 Sel ec t i on l i n e l east squares 3eans , s t andard er rors , and s i g n i f i c a n ce for s t ap l e s t reng t h , hand-pu l l grade and wool g r owth charac ter i s t i c s . : ---------------------------------------- : SELECT ION L INE ! -------------------- : ----------------------------- : ---------- : Trai t c on s i dered c FW : s i g 2 ? : ------------------------------------------------------------- : STR \ N / k t e x l 2 2 . 2 1 . 2 2 7 . 8 ? 1 . 3 * PULL ( c l ass) 5. 4 0 . 2 5 . 8 ! 0 . 1 p < . ! O LFD N,TREH? ? C j HO?E.TS Hr' STANDARD DEVIATION (SD) CLASSES FOR PAIRS OF WOGb GROWTH CHARACTERISTICS Lt.PD and LFD ( Lowe'S?:? length growth :r:ate?? and rJ.ewest. fibre Ci}iameter) 1 8 1 LP DAMP < - 1 SP 33 . 8 FOAMP LINE ? c !ZZZ.l FW Fig1;1re 8 . 5 ? EAN STAPLE STRENGTH AND THE PROPORTION OF FLEECE WEI?HT SELECT,ED ,( FW ) AND CONTROt ( C ) HOGGETS IN STANDARD DEVIATION ( SD ) CLASSES FOR PAIRS OF 'We>e>?_,.._,_.., GROWTH CHARACTERISTICS I:.PDAMP a-nd , FDhM:P ? ( Hength > ewe s ) . Anna l e s d e B i o l og i e , a n ima l B i ochemi gue , B i ophys i gue 9 : 4 9 7 - 5 1 2 . 2 1 7 G o l dma n , B . D . ( 1 9 8 2 ) . S o c i e ty f or t he S tudy o f Re p r oduct i o n 2 6 , Supp 1 : Abs t r 2 2 G o l dman , B . D . , V . Ha l l , C . H o l l i s te r , P . R oychoudhury , L . Tamar k i n and W . We s t r om ( 1 9 7 9 ) . E f f e cts o f me l a t on i n o n t he e r e pr od uct i ve sys t em i n i n tact a nd p i ne a l e c t omi zed ma l e hams t e r s ma i nta i n e d u nd e r var i o us pho t ope r i ods . Endoc r i no l ogy 1 0 4 : 8 2 - 8 8 . G raham, N . McC . ( 1 9 6 8 ) The me ta bo l i c rate o f Me r i no r ams b r e d f o r h i gh o r l ow wo o l p r o d uc t i o n . Aus t ra l i a n J o u r na l o f Agr i cu l tur a l R e s earch 1 9 : 8 2 1 - 8 2 4 . Hami l t o n , B . A . a nd J . P . Lang l a nd s ( 1 9 6 9 ) E f f i c i e ncy o f wo o l p roduc t i on o f gra z i ng s h e e p . I . D i f f e r e nces be t we e n Me r i nos se l e c ted f o r h i gh a nd l o w f l eec e we i gh t . Austra l i an J our na l o f Expe r i me nta l Agr i cu l t r e a nd An ima l Hus band ry 9 : 2 4 9 - 2 5 3 . Hammond , J . ( 1 9 5 1 ) . Cont r o l by l i gh t o f r e pr oduct i on i n f e r r e t s and m i nk . Na t u r e 1 6 7 : 1 5 0 - 1 5 1 . Hammond , J . ( 1 9 5 2 ) . Cont r o l o f r e pr oduct i on a nd pe l t change s i n f e r r e ts ; s ome e xpe r ime nt s w i t h a n ima l s k e pt e nt i r e l y upon a r t i f i c i a l l i g h t . J o u r na l o f Agr i cu l tu ra l S c i e nce 4 2 : 2 9 3 - 3 0 3 . Hammond , J . ( 1 9 5 3 ) . " E f f e c t s o f a r t i f i c i a l l i gh t i ng o n t he r e pr od uc t i ve a nd pe l t c hange s o f t he mi nk " . M onograph , He f fe r , Cambr i dge . Ha nraha n , J . P . ( 1 9 7 4 ) . Ovu la t i on r a t e as a s e l e c t i on cr i te r i a f or f e cund i ty i n s he e p . P r oceed i ngs o f the 1 s t Wo r ld Congress o f Ge ne t i cs App l i ed t o L i ve s t oc k P r oduct i on , I I I : l 0 3 3 - 1 0 3 7 . H an raha n , J . P . ( 1 9 7 6 ) . R e p eata b i l i ty o f ovu lat i on rate a nd i ts r e lat i onsh i p w i t h l i t t e r s i ze i n f o ur s h e e p b r e eds . P r oceed i ngs o f the 2 7 t h me e t i ng o f the Eur o pe a n Ass oc i a t i o n o f An ima l P r oduct i on , Z ur i c h , 6 3 0 , 5 3 8 ppl - 8 . H a rdy , J . I . and J . B . Te nnys o n ( 1 9 3 0 ) . Jour na l o f Agr i cu l tura l Res earch 4 0 : 4 5 7 - 4 6 8 . Ha r e , L o u i s e and M . J . B rya n t ( 1 9 8 2 ) . Character i s t i cs o f o e s t r us cyc l es a nd p l a sma pr o g e s t e r one pr o f i l e s o f young f ema l e sheep d u r i ng t h e i r f i r s t b r eed i ng s eas o n . An ima l Product i o n 3 5 : 1 - 7 . Har t , D . S . ( 1 9 5 3 ) . Add i t i o na l pho tope r i od i c r e s po ns e i n s he e p . Nat u r e 1 7 1 : 1 3 3 - 1 3 4 . 2 1 8 Ha r t , D . S . ( 1 9 5 5 ) . T he pho tope r i od i c a nd h o rmo ne r e sponse o f wo o l g r owt h i n s h e e p . P r oceed i ngs o f t he N ew Z e a l and S oc i e t y o f An i ma l Pr od uct i on 1 5 : 5 7 - 6 5 . Har t , D . S . ( 1 9 6 1 ) . T he e f f e c t o f l i g h t -dar k s e q u e nc e s on wo o l g r owt h . J o u r na l o f Agr i c u l t u ra l Sc i e nc e 5 6 : 2 3 5 - 2 4 3 . Har t , D . S . , J . W . B e nn e t t , J . C . D . Hutc h i ns o n , M . Wod z i cka? Toma ze ws k a ( 1 9 6 3 ) . Reve r sed pho t o pe r i od i c s e a s ons and woo l g r owth . Nat u r e 1 9 8 : 3 1 0 - 3 1 1 . Hawk e r , H . ( 1 9 8 4 ) . Twi ns a nd tr i p l e ts d on ' t hur t wo o l p r oduct i o n . N e w Z e a l and Farme r 1 0 5 ( 7 ) : 1 1 4 - 1 1 5 . Hawk e r , H . ( 1 9 8 5a ) . L i vewe ight and wo o l characte r i s t i cs o f R omney e we h ogge t s s c r e e ned o n h i gh f l e e c e we i ght . Annua l R e po r t 1 9 8 3 / 8 4 . S outhe r n S o u t h I s l and Reg i o n . Agr i c u l t u r a l R e s e a r c h D i v i s i on . N ew Z e a l a nd M i n i s t ry o f Agr i cu l t u r e a nd F i s h e r i es . p . 2 6 3 . Hawk e r , H . ( 1 9 8 5 b ) . E f f e c t s o f nutr i t i on i n wi n t e r a nd s umme r o n t h e wo o l g r owth o f Romn ey a nd P e r e nd a l e ewe s . Annua l R e p o r t 1 9 8 3/ 8 4 . S outhe r n S ou t h I s l a nd Reg i on . Ag r i cu l t ura l R e s e a r c h D i v i s i o n . New Z e a land M i n i s try o f Agr i c u l t u r e a nd F i s h e r i e s . p . 2 6 4 - 2 6 5 . Hawk e r , H . ( 1 9 8 5c ) . E f f e c ts o f s e a s on a nd nutr i t i on o n woo l g r owt h . N e w Z e a la nd Woo l Board . P r o c e ed i ngs o f a Woo l P r oduc t i o n S e m i na r , J une 1 9 8 5 , 4 ( 1 - 1 6 ) . Hawk e r , H . ( 1 9 8 6 ) . B r e e d i ng f o r mor e e f f i c i e nt f i b r e p roduct i o n . W . R . O . N . Z . P r oce ed i ngs o f a Wo o l P r oduct i o n S em i na r 5 : 4 8 - 5 3 . Hawk e r , H . and J . P . K e nn edy ( 1 9 7 8a ) . Pube r ty a nd subsequent o e s t r ous act i v i ty i n young Me r i n o e we s . Aus t ra l i an J o u r na l o f E xpe r i me nta l Agr i c u l t u r e and An i ma l Husba nd ry 1 8 : 3 4 7 - 3 5 4 . Hawk e r , H . a nd J . P . K e nnedy ( 1 9 7 8b ) . I n f l ue nce o f s eason a nd o f r e pr od uc t i ve s ta t us on the wo o l g r owth o f Me r i no e we s i n an a r i d e nv i r onme nt . Aus t r a l i an J o ur n a l o f Expe r i me nta l Agr i c u l t ure and An ima l Husba nd ry 1 8 : 6 4 8 - 6 5 2 . Hawk e r , H . , S . F . Cr o s b i e , K . F . Thomps o n a nd J . E . McEwan ( 1 9 8 4 ) . E f f e c t s o f s eason on the wo o l gr owt h r e sponse o f R omne y ewe s t o pastu r e a l l owa nce . P roc e ed i ngs o f t h e Aus t ra l i an S o c i e ty o f An ima l P r oduc t i o n 1 5 : 3 8 0 - 3 8 3 . Hawk e r , H . and S . F . Cr o s b i e ( 1 9 8 5 ) . E f f e c t s o f l e ve l o f nutr i t i o n i n w i n t e r a nd summe r o n t h e wo o l g rowth o f 2 1 9 R omne y a nd P e r e nda l e e we s wi th a h i s t o ry o f h i gh o r l ow wi n t e r wo o l gr owth . P r o c e ed i ngs o f t h e New Z e a l a nd S oc i e ty o f An i ma l P r od uc t i o n 4 5 : 2 2 5 - 2 2 8 . Hawk e r , H . , J . C . McEwan a nd J . N . C l a r k ( 1 9 8 5 ) . T h e i n f l ue nce o f s e l e c t i o n f o r h ogge t g r easy f l e ece we i ght on wo o l gr owt h pa t t e r ns . Annua l R e p o r t 1 9 8 3 / 8 4 , S o u t he r n S ou t h I s l a nd Reg i o n , Agr i cu l t u ra l Resea r ch D i v i s i o n , N e w Z e a l a nd M i n i s t r y o f Agr i cu l tu r e and F i s h e r i e s , p . 2 6 6 . Hawk e r , H . a nd L i t t l e j o h n , R . P . ( 1 9 8 6 ) . L i vewe i g h t s , f l e e cewe i gh t s and wo o l charact e r i s t i cs o f s c r e e ne d h i gh f l e ec ewe i gh t a nd r and omly s e lec ted Romney e we h ogge ts . P r oceed i ngs o f t h e New Z e a l a nd S oc i e ty o f An i ma l P r od uc t i o n 4 6 : 2 1 9 - 2 2 3 . H ea t h , H . W . a nd G . R . Lynch ( 1 9 8 1 ) . E f f ects o f 1 8 we e k s o f da i ly me l a t o n i n i n j e c t i o n o n r epr oduc t i o n a nd t empe r a t u r e r e gu l a t i on i n t h e mous e , ( Pe r omyscus l e uc opus ) . J o u r na l o f Expe r i menta l Z o o l ogy 2 1 6 : 1 9 3 - 1 9 5 . H ea t h , H . W . a nd G . R . Lynch ( 1 9 8 2 ) . I nt raspe c i f i c d i f f e r e nc e s f o r me l a t o n i n - i nd uced r e pr od uct i ve r eg r e ss i o n a nd t h e s eas ona l mou l t i n " pe r omysc us - l e uc opus " . Ge n e r a l a nd Compa ra t i ve Endocr i n o l ogy 4 8 : 2 8 9 - 2 9 5 . H e nde r s o n , A . E . ( 1 9 5 5 ) . Fau l t s i n New Z e a la nd wo o l . L i nc o l n Co l l ege T echn i ca l Pub l i ca t i o n No . 1 2 . H e nde r s on , A . E . ( 1 9 6 8 ) . G r owi ng be t t e r woo l . A . H . a nd A . W . Reed , We l l i ng t o n H e nd e r s o n , A . E . , J . McG . B ryd e n , F . E . Ma zz i t e l l i a nd K . E . M i l l i gan ( 1 9 7 0 ) . P r o t e i n s upp l eme nta t i o n a nd wo o l gr owt h . Pr oc e ed i ngs o f t h e New Z e a l and S oc i e t y o f An i ma l P r oduct i o n 3 0 : 1 8 6 - 2 0 1 . H e ue r , P . A . ( 1 9 7 9 ) . S ta p l e s t r e ngth measurement e q u i pme n t . C . S . I . R . O . D i v i s i o n o f Te xt i l e Phys i cs . P r o c e e d i ngs o f a semi nar o n s t a p l e l e n g t h a nd s tap le s t r e ng t h o f g reasy wo o l , Ryd e N SW p 6 3 - 7 8 . H eyd e nrych , H . J . , L . P . Voo s 1 o o and D . J . B . Me i s e nh e i me r ( 1 9 7 7 ) . S e l e c t i o n r e s p o ns e i n S o u th Af r i ca n Me r i n o s h e e p s e l e c t ed e i t h e r f or h i gh c l ean f le e c e mas s o r f o r a w ider S /P r a t i o . Agr oa n i ma l i a 9 : 6 7 - 7 3 . H i gh t , G . K . a nd K . E . J u ry ( 1 9 7 1 ) . H i l l Country s h e e p product i o n . I I I . S o u r c e s o f va r i a t i on i n R omne y a nd Border L e i s c e s t e r X R omney lambs a nd hogge ts . N ew Z ea land J o u r na l o f Ag r i c u l t u ra l Research 1 4 : 6 6 9 - 6 8 6 . H i gh t , G . K . , D . R . Lang a nd K . E . Jury ( 1 9 7 3 ) . H i l l C o u n t ry s h e ep p roduct i on . V . O ccure nce o f oes t r us a nd ovu la t i o n rate o f Romney a nd B o r d e r L e i ce s t e r X R omney ewe hogge ts . New Z e a l a nd J o ur na l o f Agr i c u l tura l R es e a r c h 2 2 0 1 6 : 5 0 9 - 5 1 7 . H i ght , G . K . a nd J u ry , K . E . ( 1 9 7 6 ) . H i l l Country s h e ep p r oduc t i o n . V I I I . Re la t i o ns h i p o f hogge t and two -ye a r ? o ld o e s t r us a nd ovu lat i o n r a t e t o s ubsequen t f e r t i l i ty i n R omne y a nd B o rde r Le i c es t e r X R omney ewe s . N ew Z e a l a nd J our na l o f Agr i cu l t u r a l R e s ea rch 1 9 : 2 8 1 - 2 8 8 . H i gh t , G . K . , J . J . At k i ns o n , R . M . W . S umne r a nd M . L . B i g ham ( 1 9 7 6 ) . H i l l c ountry she e p p r oduct i on VI I I . Wo o l t r a i ts o f R omne y a nd B o rder Le i c es t e r x Romn ey ewe s . N ew Z e a l a nd J o u r na l o f Agr i cu l t u r a l R e s ea rch 1 9 : 1 9 7 - 2 1 0 . H i l l , M . K . ( 1 9 7 0 ) . The e f f ect o f p la ne o f nutr i t i on o n s e a s ona l va r i a t i on i n the e f f i c i e ncy o f woo l g r owth i n Me r i n o s he e p . P r oceed i ngs o f the Aus t r a l ian S o c i e ty o f An i ma l P r oduc t i on 8 : 5 2 7 - 5 3 0 . H o f f m a n n , K . ( 1 9 7 3 ) . The i n f l u e n c e o f ph o to p e r i o d a nd me l a t o n i n o n t e s t i s s i ze , body we i ght a nd pe lage c o l o u r i n t he D j ungar i a n hams t e r ( P h odopus s ungo r i s ) . J o ur na l o f Comparat i ve P hys i o l ogy 8 5 : 2 6 7 - 2 8 2 . H o r t o n , C . T . ( 1 9 7 8 ) . S ome aspects o f w i n t e r gra z i ng sys t ems o n wo o l p r oduct i on . Thes i s , M . Agr . S c i . , Mas s ey Un i ve r s i ty , Pa lme r s ton N o r th , New Z e a l a nd . H or t o n , C . T . and G . A . W i c k ham ( 1 9 7 9 ) . The e f f ects o f w i n t e r g r a z i ng sys t ems o n some wo o l t ra i ts . P r oceed i ngs o f t h e New Z e a la nd S oc i ety o f An i ma l P r o d uct i on 3 9 : 1 0 6 - 1 1 4 . H o ussay , B . B . , J . H . P a z o C . E . Epp e r ( 1 9 6 6 ) . Ef f e cts o f t he p i ne a l g la nd upon t he ha i r cyc l e s i n m i ce . J o u r na l o f I nve s t i ga t i ve Derma t o l ogy 4 7 : 2 3 0 - 2 3 4 . Hu l e t , C . V . , E . L . W i gg i ns a nd S . K . E rcanbrack ( 1 9 6 9 ) . Oe s t r us i n r a nge lambs a nd i t s r e l a t i o nsh i p t o l i f e t i me r e pr od uc t i ve pe r f o rmance . J o u r na l o f An ima l S c i e nce 2 8 : 2 4 6 - 2 5 2 . Hu l l , F . T . L . a nd R . K . T . Hann i ng ( 1 9 8 0 ) . A p lan f or i mpr ov i ng the f e c und i ty o f a f l ock by i nd i r e c t s e lect i o n . P r o c e ed i ngs o f the New Z ea l a nd S oc i e ty o f An i ma l P r od uc t i o n , 4 0 : 2 4 0 - 2 4 7 . Hutch i ns o n , J . C . D . ( 1 9 6 5 ) . P h otope r i od i c c o ntr o l o f t he a nn ua l rhythm o f wo o l growth . I n ; " B i o l ogy o f t he s k i n a nd ha i r g r owt h " . Eds . A . G . Lyne a nd B . F . S h or t , Angus a nd R o be r t s o n , Sydney . Hutch i n s o n , J . C . D . ( 1 9 7 6 ) . P h o t ope r i od i c e f f e c t s on ha i r a nd wo o l g r owth o f d ome s t i c a n i ma l s . P r ogr ess i n B i ome t e or o l ogy B vo l 1 p t 2 : 4 7 - 6 0 . Hutch i ns o n , J . C . D . , M . Wodz i cka -Tomas zews k a ( 1 9 6 1 ) . C l i ma t e 2 2 1 phys i o l ogy o f s h e e p An i ma l B r . Abs t r . 2 9 , 1 : 1 - 1 4 H utch i ns o n , K . J . ( 1 9 6 1 ) Mea s ur ements o f wo o l pr od uct i on a nd i ts phys i o l og i ca l c ompo ne nts i n a g r oup o f S o u t h Aus tra l i a n Me r i n o s h e e p . Aus tra l i a n J o urnal o f Agr i c u l tura l Re s e a r c h 1 2 : 6 9 6 - 7 1 4 . H u tch i n s on , K . J . ( 1 9 6 2 ) . C l i ma t e c o r r e ct i on s t o t h e s e a s o na l woo l g r owth r hythm o f s h e e p graz i ng i n a S o u t he r n Aust ra l i a n e nv i r o nme n t . P r oceed i ngs o f the Aus t ra l i a n S o c i e ty o f An i ma l P r o d uc t i on 4 : 3 4 - 3 7 . H u tch i ns o n , K . J . and R . B . P o r t e r ( 1 9 5 8 ) . Gr owt h a nd wo o l produc t i o n o f Me r i n o h o gge ts re l a t ed t o graz i ng i n ta k e i n a S ou th Aus tr a l i a n e nv i r onmen t . P r oceed i ngs o f t h e Aus tra l i a n S oc i e ty o f An ima l P r od uc t i o n 2 : 3 3 - 4 1 . Hynd , P . I . ( 1 9 8 9 ) E f f e cts o f n u t r i t i on o n wo o l f o l l i c l e c e l l k i ne t i cs i n s h e e p d i f fe r i ng i n e f f i c i e ncy o f woo l pr oduct i o n . Aus t r a l i a n J ou rna l o f Agr i cu l tu r a l R e s ea rch 4 0 : 4 0 9 - 4 1 7 . I s lam, A . B . M . M . a nd R . B . L a nd ( 1 9 7 7 ) . S e a s o na l var i a t i on i n tes t i s d i ame t e r a nd s pe rm o u tput o f rams o f d i f f e r e n t pr o l i f i cacy . An i ma l P r oduct i on 2 5 : 3 1 1 - 3 1 9 . J o h ns o n , E . ( 1 9 8 4 ) . S e a s o na l ada pt i ve c o a t changes i n mamma l s . Acta Z o o l og i ca F enn i ca 1 7 1 : 7 - 1 2 . J o h nsson , I . D . , I . C . Ha r t a nd B . W . But l e r - Hogg ( 1 9 8 5 ) . The e f f ects o f e x o g e n o us b ov i ne g r owt h h o rmone a nd br omo? cr i pt i ne on g r owt h , body d e ve l opme n t , f l e ece we i g ht a nd pla sma concentra t i o n s o f Gr owth h o rmone , I ns u l i n a nd Pr o lact i n i n e we lambs . An i ma l P r oduc t i o n 4 1 : 2 0 7 - 2 1 7 . J o u be r t , D . M . ( 1 9 6 3 ) . P ube r ty i n f ema l e farm a n i ma l s . An i ma l Br e ed i ng Abs tracts 3 1 : 2 9 5 - 3 0 6 . K a r s c h , F . J . , E . L . B i t tma n , D . L . Foste r , R . L . Goodma n , S . J . Legan a nd J . E . 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Pat t e r ns o f pr oge s t e r o n e , me l a t o n i n and p r o la c t i n s e c r e t i o n i n e we s ma i nta i ned i n f o u r d i f f e r e n t p h ot op e r i ods . J o u r na l o f Endocr i n o l ogy 9 7 : 2 2 9 - 2 4 2 . 2 2 2 K e n naway , D . J . a nd T . A . G i l mo r e ( 1 9 8 4 ) . E f fects o f me l a t o n i n i mp lan t s i n e we lambs . J o ur na l o f R e pr oduct i o n a nd F e r t i l i ty 7 0 : 3 9 - 4 5 . K e nnaway , D . J . a nd T . A . G i l mo r e ( 1 9 8 5 ) . E f f ect o f me l a t o n i n i mp l an t s i n r am l ambs . J o ur na l o f R e produc t i o n a nd F e r t i l i ty 7 3 : 8 5- 9 1 . K e n n edy , J . P . ( 1 9 6 7 ) . Ge ne t i c a nd phe n o typ i c r e la t i o ns h i ps b e twe e n f e r t i l i ty and wo o l pr oduct i on i n 2 -yea r o l d Me r i n o s he e p . Aus tra l i a n J ou r na l o f Agr i c u l t ura l R e s ea r c h 1 8 : 5 1 5 - 5 2 2 . K ha t e e b , A . Al . a nd E . J o h ns o n ( 1 9 7 1 ) . S e a s o na l cha nge s o f p e l age i n t h e vo l e ( M i c r o t us agr e s t i s ) . Ge n e ra l and Compa r a t i ve Endocr i n o l ogy 1 6 : 2 1 7 - 2 4 0 . K i l g ou r , R . J . , I . W . Purv i s , L . R . P i pe r a nd K . D . Atk i ns ( 1 9 8 5 ) . He r i ta b i l i t i e s o f t e s t i s s i z e a nd s ex ua l b e hav i or i n ma l e s a nd t h e i r ge ne t i c c o r r e lat i ons wi t h mea s ur e s o f f ema l e r e p r oduct i o n . I n : " G e ne t i cs o f R e p r oduct i on i n S he e p " , ed i t or s R . B . La nd a nd D . W . R o b i ns o n , pp . 3 4 3 - 3 4 5 . L o nd o n , B u t t e rwor ths . K i tay , J . I . a nd M . D . Al t sch u l e ( 1 9 5 4 ) . " The p i ne a l g l and " , Ha r vard Un i ve r s i ty P r e s s , Cambr i dge , MAS S K o p r ows k i , J . A . a nd H . A . Tuck e r ( 1 9 7 3 ) . S e r um pr o lact i n d u r i ng va r i o us phys i o l og i ca l s ta t e s and i ts r e l a t i o ns h i p t o mi l k p r oduct i o n i n the bov i n e . 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The e xpr e s s i on o f f ema l e s ex - l i mi t ed c ha ract e r s i n t h e ma l e . Na t u r e , ( Lo ndon ) , 2 4 1 : 2 0 8 - 2 0 9 . Land , R . B . ( 1 9 7 4 ) . Phys i o l o g i ca l s t ud i e s a nd gene t i c s e l e c t i on f or s he e p f e r t i l i ty . An i ma l B r e ed i ng Abs t racts 4 2 : 1 5 5 - 1 5 8 . L a nd , R . B . ( 1 9 7 7 ) . Ge ne t i c va r i a t i on a nd i mp r oveme n t . 2 2 3 Cha pte r 2 2 , I n : " Re p r o d uc t i o n i n Dome s t i c An i ma l s " , Eds . H . H . Co l e , a nd P . T . Cupps , But t e rwo r t hs , p p . 5 7 7 - 6 0 4 . L a nd , R . B . ( 1 9 7 8a ) . Ge ne t i c i mpr ovemen t o f mamma l i a n f e r t i l i ty : A r e v i e w o f o pp o r t un i t i e s . An i ma l R ep r oduct i on Sc i e nce . 1 : 1 0 9 - 1 3 5 . Land , R . B . ( 1 9 7 8 b ) . Re p r o d u c t i o n i n young s he e p : s o me g e ne t i c and e nv i r o nme n ta l s o u rces o f var i a t i on . J o u r na l o f R epr oduct i on a nd Fe r t i l i ty . 5 2 : 4 3 7 - 4 3 6 . Land , R . B . a nd W . R . Ca r r ( 1 9 7 5 ) . Te s t i s gr owt h and p l a sma L H c o nc en t rat i on f o l l owi ng hemi cas t rat i on a nd i ts r e la t i o n w i t h f ema l e p r o l i f i cacy i n s he ep . J o u r na l o f R e p r oduc t i o n a nd Fe r t i l i ty 4 5 : 4 9 5 - 5 0 1 . Land , R . B . a nd W . R . Ca r r ( 1 9 7 9 ) . R e pr oduct i o n i n d ome s t i c a n i ma l s . I n : " Gene t i c va r i a t i o n i n h o rmon e s ys t e ms " . Vo l . 1 . CRC p r e s s , J . G . M . S q u i r e ( Ed . ) FL . p 8 9 - 1 1 2 . Lang , W . R . ( 1 9 5 2 ) . An oma l ous wo o l gr owt h i n a Me r i n o f l e e c e . J ou r na l o f t h e Aus t r a l i a n I ns t i t ute o f Agr i c u l t u r a l S c i e nce 1 8 : 1 0 8 - 1 0 9 . Lan g l a nd s , J . P . a nd B . A . Hami l t on ( 1 9 6 9 ) . E f f i c i e ncy o f wo o l p r oduct i o n o f gra z i ng s he e p . 2 . D i f f e r e nces b e twe e n b r e eds a nd s tra i ns var y i ng i n age . Aus t ra l i a n J o u r na l o f Expe r ime nta l Ag r i c u l t u r e a nd An ima l H us ba nd r y 9 : 2 5 4 - 2 5 7 . L a ng l a nds , J . P . a nd J . L . Whe e l e r ( 1 9 6 8 ) . The dyeband i ng a nd t a t t o o pa tch p rocedur e s f o r e s t ima t i ng wo o l p r oduct i on a nd o bta i n i ng samp l e s f o r t h e measur eme n t o f f i b r e d i ame te r . Aus t ra l i an J o u r na l o f Expe r i me nta l Agr i c u lt u r e a nd An ima l Husbandry 8 : 2 6 5 - 2 6 9 . La r ge , R . V . ( 1 9 7 0 ) . The b i o l og i ca l e f f i c i e ncy o f mea t p r oduct i on i n s h e e p . An i ma l P r oduct i on . 1 2 : 3 9 3 - 4 0 1 . La r os e , P . a nd A . S . Twe ed i e ( 1 9 3 8 ) . The i n f l ue nce o f n u t r i t i o na l a nd c l i ma t i c fa c t o r s o n wo o l gr owt h a nd q ua l i ty . I I . Labora t o ry me thods used i n measur eme nt o f wo o l characte r s . 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I s o la t i o n o f me l a t o n i n , t he p i nea l g la nd fac t o r t ha t l i gh t e ns me l a n ocyt e s . J o ur na l o f the Ame r i can Chem i s t ry S oc i e ty 8 0 : 2 5 - 8 7 . L e we r , R . P . ( 1 9 7 8 ) . A s t udy o f ge ne t i c and e nv i r o nme nta l va r i a t i o n a nd c ovar i a t i on i n p r od uc t i ve tra i ts o f a f l ock o f P e r e nda l e s h e e p . Thes i s , P h . D . Mas s ey Un i ve rs i ty , Pa lme rs t o n N or t h . L i nc o l n , G . ( 1 9 8 3 ) . Me l a t o n i n a s a s e a s o na l t ime -cue : a c omme r c i a l s t o r y . Na tu r e 3 0 2 : 7 5 5 . L i n c o l n , G . A . ( 1 9 8 4 ) . Ce n t ra l e f f e c t s o f ph o t o pe r i od on r e produc t i on i n the ram r e vea l ed by the use o f a t e s t os t e r one c l amp . J . End ocr . 1 0 3 : 2 3 3 - 2 4 1 L i nco l n , G . A . , A . S . McNe i l l y a nd C . A . Came r on ( 1 9 7 8 ) . The e f f e c t s o f a s udden d e c r eas e o r i nc r eas e in day l e ngth on p r o l ac t i n s e c r e t i o n i n t he r am . J o ur na l o f Re p r oduc t i on a nd Fe r t i l i ty 5 2 : 3 0 5 - 3 1 1 . L i nc o l n , G . A . , H . K la nd o r f a nd N . And e r s o n ( 1 9 8 0 ) . P h o t ope r i od i c c o nt r o l o f t hyr o i d f unct i on a nd wo o l a nd h o r n gr o wt h i n rams a nd t he e f f e c t o f c ran i a l sympat h e c t omy . Endocr i no l ogy 1 0 7 : 1 5 4 3 - 1 5 4 8 . L i nc o l n , G . A . a nd R . V . S h o r t ( 1 9 8 0 ) . S e a s o na l breed i ng : Na t u r e ' s c ontracept i ve . R ecent P r ogr e s s i n H ormone R e search 3 6 : 1 - 5 2 . L i nc o l n , G . A . , O . F . X . A lme i da , H . K la ndo r f a nd R . A . Cun n i ngham ( 1 9 8 2 ) . H o ur l y f l uctua t i o ns i n the b l ood l e ve l s o f me l a t on i n , pr o lact i n , L H , FS H , t hyr o x i ne , a nd co r t i s o l i n rams und e r a r t i f i c i a l p h o t ope r i ods , a nd t h e e f f e ct o f cran i a l sympath e c t omy . J o u r n a l Edocr i no l ogy 9 2 : 2 3 7 - 2 4 4 . L i nc o l n , G . A . a nd F . J . P . E b l i ng ( 1 9 8 5 ) . E f f e ct o f c onstan t ? re l eas e i mp lants o f me l a t o n i n o n s e a s o na l cyc l es i n r e pr oduct i on , pr o lact i n s e c r e t i o n a nd mou l t i ng i n r ams . J o u r na l o f Re p r oduc t i o n a nd Fe r t i l i ty 7 3 : 2 4 1 - 2 5 3 . L i nd \ e r , H . R . a nd K . A . F e rguson ( 1 9 5 6 ) . I n f l ue nce o f t h e ad r e na l c o r te x o n wo o l g r owth a nd i t s r e lat i o n to 2 2 5 ' br ea k ' a nd ' t e nd e r ne s s ' o f the f l e e c e . Na t u r e 1 7 7 : 1 8 8 - 1 8 9 . L oga n , A . and B . Wea t h e r head ( 1 9 8 0 ) . P o s t - tyr os i na s e i nh i b i t i o n o f me la noge ne s i s by me l a to n i n i n ha i r f o l l i c l e s i n v i vo . J o ur na l o f I nves t i ga t i ve De rma t o l o gy 7 4 : 4 7 - 5 0 . Lynch , G . R . , A . L . Eps t e i n ( 1 9 7 6 ) . Me l a t o n i n i nd uc ed change s i n g onads , pe lage a nd t h e rmoge n i c characte r s i n the wh i te - f o oted mou s e ( Pe r omyscus l e uc opus ) . C ompa r a t i ve B i ochemi s t ry a nd P hys i o l ogy Abs tracts 5 3 : 6 7 - 6 8 . Lyne , A . G . ( 1 9 6 4 ) . E f f e c t o f adve r s e nut r i t i on o n t h e s k i n a nd woo l f o l l i c l e s i n Me r i n o s he e p . Aus t ra l i a n J o u r na l o f Agr i cu l t u r a l R e s e a r c h 1 5 : 7 8 8 - 8 0 1 . Lyne , A . G . , M . J o l l y , D . E . H o l l i s ( 1 9 7 0 ) . E f f e c t s o f e xpe r ime nta l ly p r oduced l oca l s ubde rma l t emp e r a t u r e c ha nges on s k i n t empe ra t u r e a nd woo l g r owt h i n t h e s he e p . J o u r na l o f Agr i c u l t u r a l Sc i e nce 7 4 : 8 3 - 9 0 . Madd o ck s , s . , Y . Chand ra s e k ha r , B . P . S e tche l l ( 1 9 8 5 ) . E f f e c t o n woo l gr o wt h o f t hyr o x i ne r e p lacemen t i n t h r o idectomi z ed Me r i n o rams . Aus t ra l i an J o u r na l o f B i o l ogy S c i e nc e 3 8 : 4 0 5 - 4 1 0 . Ma rg o l e na , L . A . ( 1 9 6 0 ) . S e a s o n a nd compa ra t i ve a c t i v i t y o f woo l f o l l i c l e s . Ana t om i c a l Record 1 3 8 : 3 6 8 - 3 7 2 . Ma r s t o n , H . R . ( 1 9 2 8 ) . The c h em ica l c ompo s i t i o n o f woo l . B u l l e t i n N o . 3 8 . , C ounc i l o f S c i e nt i f i c a nd I ndu s t r i a l R esearch , Aus t ra l i a . Mar s t o n , H . R . ( 1 9 4 8 ) . N u t r i t i o na l fact ors i nv o l ved i n wo o l p r od uct i o n by Me r i n o s he ep . I . The i n f l ue nce o f f odde r i ntake on t h e r a te o f wo o l gr owt h . Aus t r a l i a n J o u r na l o f S c i e nt i f i c R esea r ch B 1 : 3 6 3 - 3 7 5 . Mar s t o n , H . R . a nd A . W . P i e r ce ( 1 9 3 2 ) . The e f f e c t s f o l l ow i ng t hyr o idect omy i n Me r i n o s he e p . Aus t ra l i an J o u r na l o f Expe r ime nta l B i o l og i ca l a nd Med i ca l S c i e nce 1 0 : 2 0 3 - 2 1 6 . Ma r t i ne t , L . , J . P . Rava u l t a nd M . Me un i e r ( 1 9 8 2 ) . S ea s ona l var i a t i ons i n mi nk p l a sma pr o l act i n measu r ed by h e te r o l ogous rad i o - i mmunoassay . Ge n e ra l and Compa ra t i ve Endocr i no l ogy 4 5 : 7 1 - 7 5 . Ma tthews , C . D . , A . l e C o r nu , D . J . K ennaway a nd R . F . S eama r k ( 1 9 7 8 ) . P i nea l f un c t i o n i n pr egnancy . A s t udy o f me l a t on i n r hythms i n t h e human and the she e p . The e f f e cts of p i nea l e c t omy i n the she e p . J o u r na l of Ne u r a l T ransmi t i o n , S up p l eme n t 1 3 : 3 7 7 - 3 7 8 . McCl e l l a nd , L . A . , C . M . C l a r k , H . T . B la i r , D . D . S . McK e n z i e a nd S . N . McCutche o n ( 1 9 8 7 ) . S ome phys i o l og i ca l cha nge s 2 2 6 i n s he e p s e l e c ted f o r h i gh yea r l i ng wo o l p r oduc t i on . P r oceed i ngs o f the 4 t h As i a n-Aus t ra las i an As s o c i a t i o n o f An i ma l P r od uc t i o n S o c i e t i e s . p . 3 7 5 . McCl e l l a nd , L . A . , G . A . W i c k ham and H . T . B la i r ( 1 9 8 7 ) . E f f i c i e ncy o f R omne y h ogge ts f r om a f l e e ce we i gh t s e l e ct ed f l oc k . P r o c e ed i ngs o f t h e 4 t h As i an? Aus t ra las i a n Ass oc i a t i on o f An i ma l P r oduct i on S oc i e t i e s . p . 3 2 9 . McC l e l l a nd , L . A . , H . T . B l a i r , G . A . W i c k ham and I . M . B r o o k e s ( 1 9 8 6 ) . A c ompa r i s o n o f f l e e c ewe i gh t -s e l ec t ed a nd c o n t r o l R omney rams f or i nta k e , l i ve we ight ga i n , wo o l gr owth a nd f e e d u t i l i sa t i on . P r oceed i ngs o f t he N ew Z e a l a nd S oc i e ty o f An i ma l P r oduct i on 4 6 : 2 1 5 - 2 1 8 . McCo r d , C . P . a nd F . P . A l l e n ( 1 9 1 7 ) . Ev i d ences a s s o c i a t i ng p i nea l g l a nd f u nc t i o n w i t h a l t e ra t i ons i n p i gmen ta t i on . J o u r na l o f Expe r ime n ta l Z o o l ogy 2 3 : 2 0 7 - 2 2 4 . McCutch e o n , S . N . , D . D . S . Mac k e nz i e and H . T . B la i r ( 1 9 8 7 ) . N i t r ogen me tabo l i sm a nd p lasma u r ea c oncentra t i o n s i n f l e ecewe i gh t - s e l ec t e d a nd c o n t r o l R omney rams . Aus tra l i an J o u r na l o f Agr i c u l t u ra l R esearch 3 8 : 9 1 7 - 9 2 6 . McD o na ld , B . J . ( 1 9 8 4 ) . P h o t o pe r i od i c c o nt r o l o f f i br e p r od uc t i o n i n the cas hme r e - bear i ng goat . P r oceed i ngs o f the l O t h I nt e r na t i ona l Cong r e s s o f B i ome t e or o l ogy, T o kyo , 1 9 8 4 . McD o na l d , B . J . ( 1 9 8 5 ) . T he cashme r e gr owt h cyc l e . Occass i o na 1 pape r p r e s e nted a t t h e 1 s t I n t e r na t i o na l Cas hme r e S em i na r , Canbe r r a , 1 9 8 5 . McFar lane , J . D . ( 1 9 6 5 ) . T he i n f l ue nce o f s e a s ona l pas tu r e pr oduct i on a nd gra z i ng manageme n t o n s e asona l wo o l g r owth . Aus t ra l i a n J o u r na l o f Expe r imen t a l Agr i cu l tu r e a nd An i ma l Husbandry 5 : 2 5 2 - 2 6 1 . McFar lane , W . V . , C . H . S . D o l l i ng a nd B . Howard ( 1 9 6 6 ) . D i s t r i bu t i on a nd t u r nove r o f wat e r i n Me r i no s h e e p s e l e c t ed f o r h i gh wo o l p roduct i on . Aus t ra l i a n J o u r na l o f Agr i c u l tu r a l R e s ea rch 1 7 : 4 9 1 - 5 0 2 . McGu i r k , B . J . ( 1 9 7 6 ) . Re l e va nce f o r p r od ucers o f r e s ea rch i nt o t h e gene t i c i mpr oveme n t o f r e pr oduct i ve pe r f ormance . P r oce e d i ngs o f t h e Austra l i a n S oc i e ty o f An ima l P r oduct i on 1 1 : 9 3 - 1 0 0 . McGu i r k , B . J . ( 1 9 7 9 ) . S e l e c t i on f o r wo o l pr oduc t i o n i n Me r i no s h e e p . I n : " S e 1 e c t i o n e xper i me nts i n l a b o ra t o r y a nd dome s t i c a n i ma l s " . Ed . A . Robe r t s o n , Commonwe a l t h Agr i c u l t ur a l Bureau x . pp . 1 7 6 - 1 9 7 . McGu i r k , B . J . ( 1 9 8 3 ) . Ge ne t i c s e l e c t i o n f o r wo o l pr oduct i o n . I n : " S h e e p P r oduct i o n " , Ed . W . Ha r e s i gn , But t e rwo r t h s , 2 2 7 L ondon . pp . 5 4 5 - 5 6 6 . McGu i r k , B . J . and K . D . Atk i ns ( 1 9 7 6 ) . I n : S h e e p B r e e d i ng , p roce e d i ngs o f t h e 1 9 7 6 I nt e r na t i ona l Cong r e s s , Mure s k , We s t e r n Aus t ra l i a , Augus t , 1 9 7 6 . pp . 1 0 0 - 1 0 4 . ( We s t e r n Aus t ra l i a n I ns t i t u t e o f Techno l ogy, Pe r t h , We s t e r n Aus t r a l i a . ) McGu i r k , B . J . , J . R . Payn t e r , R . B . Dun ( 1 9 6 4 ) . The e f f e c t o f f r e que ncy a nd t ime o f s hear i ng on the r eproduc t i o n and woo l g r owth o f Bunga r e e S outh Aus t ra l i a n Me r i n o ewes . Aus t ra l i a n J o u r na l o f Expe r ime n ta l Agr i cu l t u r e and An i ma l Husba nd ry 4 : 3 0 5 - 3 1 0 . McGu i r k , B . J . and K . D . At k i ns ( 1 9 7 6 ) . R esponse t o s e l e c t i o n f or i nc r ea s ed f l e ec e we i ght i n Me r i n o s he e p . I n : S he e p B reed i ng . Pr o c e ed i ngs o f the 1 9 7 6 I n te r nat i o na l Congr es s , Mur e s k and P e r th , W . A . , Ed s . Tome s , G . J . , D . E . R obe r t s o n a nd R . J . L i ght f o o t pp . 1 0 0 - 1 0 4 . McManus , W . R . , G . W . Ar n o l d a nd M . L . Dud i ns k i ( 1 9 6 6 ) . S t ud i e s i n woo l p r oduc t i on o f g ra z i ng s he e p . 4 . Va r i a t i on be twe e n s he e p i n i nta k e , wo o l p r oduct i o n and e f f i c i e ncy . Aus t ra l ian J ourna l of Expe r i me nta l Agr i cu l tu r e and An i ma l Husband ry . 6 : 9 6 - 1 0 0 . McM i l lan , W . H . ( 1 9 8 1 ) . A s t udy o f s ome fact o r s a f f e c t i ng r epr oduct i on i n o n e -and two-year o ld e wes . Thes i s , Ph . D . , Ma s s ey Un i ve r s i ty , Pa lme rs t o n N o r t h . McM i l la n , W . H . and McD o na ld , M . F . ( 1 9 8 3 ) . R e pr od uct i on i n ewe lambs a nd i ts e f f e c t o n two -year - o l d pe r f o rmance . New Z e a l and J o u r na l o f Agr i c u l t u ra l R e s earch . 2 6 : 4 3 7 - 4 4 2 . Meye r , H . H . a nd F r e nc h , R . L . ( 1 9 7 9 ) . H ogget l i ve - we i ght ? o e s t r us r e la t i o ns h i ps among s h e ep b r e ed s . P r oc e ed i ngs o f t h e New Z e a l a nd S oc i e ty o f An i ma l P r oduct i on 3 9 : 5 6 - 6 2 . M i rach i , R . E . , B . E . H owland , P . F . S can l on , R . L . K i r k pat r i ck and L . M . S ta n f o r d ( 1 9 7 8 ) . Seas ona l va r iat i o n i n p lasma L H , F S H , p r o l ac t i n , and t e s t oste r one c o n c ent ra t i ons i n ad u l t ma l e wh i te -ta i l ed deer . Canad ian J o u r na l o f Z o o l ogy 5 6 : 1 2 1 - 1 2 9 . M oh n , M . P . ( 1 9 5 8 ) . The e f f e cts o f d i f f e r e nt hormona l s tat es on t h e gr owth o f ha i r i n rats . I n : " The B i o l ogy o f ha i r gr owt h " , Academ i c P r e s s , NY , pp 3 3 5 - 3 9 8 . M on tgome ry , G . W . ( 1 9 8 7 ) . S e a s ona 1 i ty o f oes t r us a nd ovu lat i on r a t e . P r oceed i ngs o f the 4 t h As i a n Aust ra las ian As s o c i a t i o n o f An ima l P r oc uc t i o n An i ma l S c i ence Congr e s s , Hami l t on , N . Z . p 2 5 2 . M o ntgome ry , G . W . a nd H . Hawk e r ( 1 9 8 7 ) . S eas ona l r e p r od uct i o n i n e we s s e l e c ted on s eas o na l changes i n wo o l g r owth . J o ur na l o f R e pr oduct i on and Fe r t i l i ty 7 9 : 2 0 7 - 2 1 3 . 2 2 8 M o o r e , R . W . a nd C . H . S . Do l l i ng ( 1 9 6 1 ) Ab i l i ty t o s e l e c t d i e t i n Me r i no s h e ep f ed i n pe ns . Aus t ra l i a n J o ur na l o f Expe r i me nta l Agr i c u l ture a nd Ann i ma l Hus bandry 1 : 1 5 - 1 7 . M o or e , R . W . , T . W . K n i ght a nd D . Whyman ( 1 9 7 8 ) . I n f l ue nce o f h ogge t o e s t r us o n s ubseque n t e we f e r t i l i ty . P r oceed i ngs o f t h e N ew Z e a l and S o c i e ty o f An i ma l P r oduct i on , 3 8 : 9 0 - 9 3 . M o o r e , R . W . a nd D . C . Sme a t on ( 1 9 8 0 ) . E f f e cts o f d i f f e r ent gr owt h pa ths f r om 4 t o 1 1 mon t hs o f age o n R omney h ogget o e s t r us a nd s ubs equent r e pr od uct i on . P r oceed i ngs o f t h e N ew Z e a l and S oc i e ty o f An i ma l Produc t i on 4 0 : 2 7 - 3 3 . M o o r e , R . W . a nd H -U . P . H oc key ( 1 9 8 2 ) . The e f fe c t o f ear l y n u t r i t i o n a nd hogge t o e s t r us o n s ubseque nt r e pr oduct i on . P r oceed i ngs o f the New Zea l and S oc i e ty o f An ima l P r oduct i o n 4 2 : 4 1 - 4 3 . Mo r l ey , F . H . W . , L . W . L o c ka r t a nd E . C . Dav i s ( 1 9 5 5 ) . The va l u e o f p roduct i o n f r om a c l i pped measured a r ea as a n i nd e x o f f l e ec e we i gh t . Aus ta l i a n J ourna l o f Ag r i c u l tura l Resea rch 6 : 9 1 - 9 8 . Mor r i s , L . R . ( 1 9 6 1 ) . P ho t ope r i od i c i ty o f s easona l r hythm o f wo o l gr owth i n s hee p . Na t u r e 1 9 0 : 1 0 2 - 1 0 3 . M or r i s o n , D . F . ( 1 9 7 6 ) . M u l t i var i a t e s ta t i s t i ca l me t h ods . 2nd Ed i t i o n , McGraw- H i l l I nc . M ou l e , G . R . ( 1 9 6 5 ) . F i e l d i nve s t i ga t i ons w i t h s h e e p : A manua l o f t echn i que s . C . S . I . R . O . Munr o , C . J . , K . P . McNatty a nd L . R e n shaw ( 1 9 8 0 ) . C i r ca ? a nnua l r hyt hms o f p r o lact i n s e c r e t i on i n e we s a nd t h e e f f e c t o f p i nea l e c t omy . J o ur na l o f Endocr i n o l ogy 8 4 : 8 3 - 8 7 . Nag o r c ka , B . N . ( 1 9 7 7 ) . The d e sc r i pt i on a nd ana lys i s o f wo o l g r owt h . Aus t r a l i an J o ur na l o f Agr i c u l tura l Re s ea r ch 2 8 : 7 3 7 - 7 4 6 . Nag o r c k a , B . N . ( 1 9 7 9 ) . The e f f e c t o f p hotoper i od o n wo o l g r owt h . I n : " P hys i o l og i ca l and Env i r onmenta l L i mi tat i ons t o Woo l Gr owt h " , Eds . J . L . B lack a nd P . J . Re i s , U . N . E . Pub l i s h i ng Un i t , Arm ida l e , N . S . W . pp . Ne t t , T . M . a nd G . D . N i swe nde r ( 1 9 8 2 ) . I n f l ue nce o f e x ogen ous me l a t o n i n o n seas o na l i ty o f r e pr od uc t i o n i n s he e p . Ther i oge n o l ogy 1 7 : 6 4 5 - 6 5 3 . N eyma n , J . a nd E . S . P ea r s o n ( 1 9 2 8 ) . On the use a nd 2 2 9 i n t e r pr e ta t i o n o f ce r ta i n t e s t c r i t e r i a f o r purpose o f s ta t i s t i ca l i n f e r e nce . B i ome t r i k a 2 0 A , pp1 7 5 - 2 4 0 ; 2 6 3 - 2 9 4 . N i r , I . ( 1 9 7 8 ) . N o n - r e pr oduc t i ve sys t ems and the p i ne a l g l and . J o u r na l o f Ne ura l Transm i t i on , S u ppl eme n t 1 3 : 2 2 5 - 2 4 4 . N i r , I . , R . J . R e i te r , R . J . Wur tman ( 1 9 7 8 ) . The p i ne a l g land . J o ur na l o f N e ura l og i ca l Transmi t i o n , S upp l eme nt 1 3 : 2 4 5 - 2 5 6 . N i tt e r , G . ( 1 9 7 8 ) . B r e ed ut i l i za t i o n f or mea t p r oduct i on i n s h ee p . An i ma l B r e ed i ng Abs tracts 4 6 : 1 3 1 - 1 4 3 . N o r r i ss , M . H . a nd C . C . C laa s e ns ( 1 9 3 1 ) . Cr i mp i n woo l as a pe r i od i c f unc t i on o f t ime . J o u r na l o f t he Te x t i l e I ns t i tu t e 2 2 : T 2 2 4 - 2 4 0 . Nowa k , R . a nd Rodway , R . G . ( 1 9 8 5 ) . E f f e c t o f i nt r avag i na l i mp lant s o f me l a t on i n o n the ons e t o f ovar i a n act i v i ty i n adu l t a nd p r e pube r ta l e wes . J o u r na l o f R epr oduct i o n a nd F e r t i l i ty , 7 4 : 2 8 7 - 2 9 3 . Orwi n , D . F . G . , J . L . Wo ods and K . H . E l l i o t ( 1 9 8 0 ) . Compos i t i on o f t he c o r t e x o f s o und a nd t e nd e r woo ls . ? r o c e ed i ngs o f the 6 t h I nt e r na t i o na l Wo o l Te x t i l e R e s e a r c h C on f e r e nce , ? r e t or i a . Vo l I I , pp . 1 9 3 - 2 0 6 . Orwi n , D . F . G . , J . L . Woods a nd R . G . G ourd i e ( 1 9 8 5 ) . Co r t i ca l c e l l type a nd wo o l s t r e ngth . ? r oce ed i ngs o f t h e 7 t h I nt e r na t i o na l Woo l T ext i l e s Re s ea rch C o n f e r e nc e , T okyo , Vo l 1 , p p . 1 9 4 - 2 0 3 . Orwi n , D . F . G . , K . G . G e e nty and J . N . C l a r k e ( 1 9 8 6 ) . Br e ed i ng f or i mpr oved s ta p l e s t r e ngth . W . R . O . N . Z . ? r o c e ed i ngs o f t h e Woo l P r oduct i on S em i nar 5 : 3 4 - 3 8 . Pana r e t t o , B . A . ( 1 9 7 9 ) . E f f ects o f l i ght o n cyc l i c act i v i ty o f wo o l f o l l i c l e s and poss i b l e r e la t i o ns h i ps t o changes i n t he pe lage o f o t he r mamma l s . I n : ' P hys i o l og i ca l a nd Env i r onme n t a l L i mi ta t i o ns t o woo l gr o wt h ' , Eds . J . L . B lack a nd P . J . Re i s , U . N . E . P ub l i s h i ng Un i t , Armida l e , N . S . W . p p . Pana r e t t o , B . A . , R . E . Chapma n , A . M . Down es , P . J . R e i s , A . L . C . Wa l l ac e ( 1 9 7 5 ) . S ome e f f e c t s o f t h r e e g l uc o c o r t i c o i d ana l ogue s on wo o l gr owt h and t h e i r e f f i cacy a s d e f l e ec i ng agents i n s he e p . Aus t ra l ian J ourna l o f E xpe r i men ta l Agr i cu l tu r e and An i ma l Husbandry 1 5 : 1 9 3 - 2 0 2 Pa na r e t t o , B . A . and A . L . C . Wa l lace ( 1 9 7 8a ) . The adm i n i s t ra t i o n o f f l uome t has one by t h r e e d i f f e r e nt r ou te s , i t s measur eme n t i n t h e p lasma a nd s ome e f f e c t s o n wo o l g r owt h i n Mer i no we t he r s . Aus t r a l ian J ourna l o f 2 3 0 B i o l og i ca l Sc i e nce 3 1 : 6 0 1 - 6 2 0 . P a na r e tt o , B . A . and A . L . C . Wa l lace ( 1 9 7 8 b ) . Dexame thasone c oncentra t i ons i n ov i ne p l asma dur i ng i ts i n t ra ve nous i n f us i on , i t s r e l a t i o n t o t h e pr oduct i on o f s ome e nd ogenous hormo n e s a nd s ome o f t he e f f e c t s o n wo o l g r owt h . Aus tra l i a n J o u r na l o f B i o l og i ca l S c i e nc e 3 1 : 2 4 7 - 2 5 6 . P a na r e t t o , B . A . and A . L . C . Wa l l ace ( 1 9 7 9 ) . Syne r g i s t i c e f f ects o f th i ocyna t e w i t h f l u ome thasone i n i nh i b i t i ng wo o l gr owt h i n Me r i n o we t he r s . Aus t ra l i a n J o u r na l o f B i o l og i ca l Sc i e nc e 3 2 : 7 7 - 9 0 . Pa n g , S . F . and A . E . Al l e n ( 1 9 8 6 ) . Extra - p i nea l me l a t o n i n i n t he r e t i na : I t s r e gu la t i o n a nd phys i o l og i ca l f unct i o n . P i nea l Research R ev i ews 4 : 5 5 - 9 5 . Pa t t i e , W . A . and R . Ba r l ow ( 1 9 7 4 ) S e l e c t i o n f o r c le a n f l e e c e we i gh t i n Me r i n o s he e p . I . D i r e c t r e sponse t o s e l e c t i on . Aus t ra l i a n J o u r na l o f Agr i c u l t ur a l Re s e a r c h 2 5 : 6 4 3 - 6 5 5 . P a t t i e , W . A . and A . J . W i l l i a ms ( 1 9 6 7 ) . S e l e ct i on f or wea n i ng we i ght i n Me r i no s he e p . I I I . Ma i n tenance r e qu i r eme n t s a nd t he e f f i c i e ncy o f c o nve r s i o n o f f e ed t o woo l i n ma ture ewes . Aus t r a l i a n J o u r na l o f Exper ime nta l Agr i cu l ture a nd a n i ma l Husbandry 7 : 1 1 7 - 1 2 5 . P e l l e t i e r , J . ( 1 9 7 3 ) . E v i de nce f o r pho toper i od i c c o n t r o l o f p r o lact i n r e l ea s e i n r ams . J ou rna l o f Repr oduct i on a nd Fe r t i l i ty 3 5 : 1 4 3 - 1 4 7 . P e l l e t i e r , J . , S . Car r e z - Camous a nd J . C . Th i e r y ( 1 9 8 1 ) . Ba s i c neur o end oc r i ne e ve n ts be f o r e pube r ty i n ca t t l e , s h e e p a nd p i gs . J o ur na l o f R e pr oduct i on a nd Fe r t i l i ty , S upp l ement 3 0 : 9 1 - 1 0 2 . P e t e r s , R . R . and H . A . Tuc k e r ( 1 9 7 8 ) . P r o lact i n a nd gr owt h h ormone res pons e s t o p h o t o pe r i od i n he i f e r s . Endocr i n o l ogy 1 0 3 : 3 2 9 - 3 3 6 . Pe t e r s o n , A . J . , L . B od i n , J . F . S m i t h and J . N . C l a r k e ( 1 9 8 6 ) . P hys i o l ogy o f s he e p s e l e ct e d f or pr o l i f i cacy . N ew Z e a land Mi n i s t ry o f Agr i c u l ture a nd F i s he r i e s , R e s e a r c h D i v i s i on Annua l R e p o r t 8 5/ 8 6 . p 3 2 - 3 3 . P e t t e r b o rg , L . J . ( 1 9 8 6 ) . P h o t ope r i od , p i nea l a nd r e pr oduct i on i n t h e wh i te - f o o ted mous e , ( Pe r omys cus l e ucopus ) . Adva nce s in P i ne a l Res earch , Vo l . 1 . R . J . Re i t e r and M . K a rase k , eds . , J ohn L i bbey & Co . L td . , pp . l 7 9 - 1 8 3 , L ondon . P i pe r , L . R . and B . M . B i nd o n ( 1 9 8 2 ) The Boor o o l a Me r i no and the pe r f ormance o f med i um n o n -Pepp i n cr o s s e s a t Armida l e . I n : " Th e B o or o o la Me r i no " , P r oce ed i ngs o f a wor k sh op he ld i n Arm i da l e , Augus t , 1 9 8 0 . C . S . I . R . O . D i v i s i on o f An i ma l Pr oduct i on . pp . 9 - 2 0 . 2 3 1 P i pe r , L . R . a nd C . H . S . Do l l i ng ( 1 9 6 6 ) . Va r i a t i o n i n the s u l phur c o n t en t o f wo o l o f Mer i n o s he e p ass oc iated w i t h gene t i c d i f f e r e nces i n woo l - p r oduc i ng capac i ty . Aust ra l i an J o u r na l o f B i o l og i ca l S c i e nce 1 9 : 1 1 7 9 - 1 1 8 2 . P i pe r , L . R . a nd C . H . S . D o l l i ng ( 1 9 6 9 ) E f f i c i e ncy o f c onve r s i on o f f o od i n t o wo o l . V . C ompa r i s on o f t he appa r e nt d i ges t i ve a b i l i t y o f s he e p s e l e cted f o r h i g h c l ean woo l we i gh t wi t h that o f s h e e p f r om a random c o nt r o l gr o up . Aus t ra l ia n J o ur na l o f Ag r i c u l tura l R e s earch 2 0 : 5 7 9 - 5 8 7 . P ur v i s , I . W . ( 1 9 8 7 ) . Ge ne t i c impr oveme nt o f r epr oduc t i ve e f f i c i ency i n Mer i no s h e e p - s e l e c t i on cr i te r i a . P r oc e ed i ngs o f the 6 t h Aus tra l i a n Ass o c iat i on o f An i ma Breed i ng a nd Ge ne t i cs C on f e r e nce , P er t h , WA . , F eb 9 - 1 1 . pp . 2 4 2 - 2 4 4 . Q u i r k e , J . F . ( 1 9 7 8 ) . Ons e t o f pube r ty a nd o e s t r us act i v i ty i n Ga lway, F i nn i s h La ndrace a nd F i nn -c r o s s ewe l ambs dur i ng the i r f i r s t br e e d i ng s eas o n . I r i s h J ourna l o f Agr i cu l tura l R e s earch 1 7 : 1 5 - 2 3 . Qu i r k e , J . F . ( 1 9 7 9 ) . E f f e c t o f body we i ght o n the a tta i nme nt o f pube r ty and r e pr oduc t i ve pe r f o rmance o f Ga lway and F i nga l way f ema l e l ambs . An ima l P r od uct i o n 2 8 : 2 9 7 - 3 0 7 . Qu i r k e , J . F . ( 1 9 8 1 ) . Re g u la t i on o f pube r ty a nd r e pr od uct i on i n e we l ambs : A r ev i e w . L i ve s t ock P r od u c t i on Sc i e nce 8 : 3 7 - 5 3 . Qu i r k e , J . F . and J . P . Hanrahan ( 1 9 8 5 ) . B r e e d d i f f e r e nces i n t he breed i ng s e a s o n i n s he e p . I n : " End ocr i ne causes o f s easona l a nd l a ctat i ona l a n o e s t r us i n Farm An ima l s " . Eds . F . E l l e nd o r f f and F . E l sae s s e r , Ma r t i nus -N i j ho f f , Pub l i s h e r s . Q u i r k e , J . F . , G . H . S tabe n f e l d t a nd G . E . Bra d f ord ( 1 9 8 5 ) . Ons e t o f pube r ty a nd d u ra t i o n o f the b r e e d i ng seas o n i n S u f f o l k , Ramb o i l l e t , F i nn i s h Land race , D o rset a nd F i nn? Do r s e t ewe l ambs . J o u r na l o f An ima l S c i e nce 6 0 : 1 4 6 3 1 4 7 1 . Rae , A . L . ( 1 9 5 8 ) G ene t i c va r i a t i on and c ova r i a t i on i n pr od uct ive characters o f New Z e a l a nd R o?ney Ma r s h shee p . N ew Z e a l and J ou rna l o f Agr i cu l t u r a l R esearch 1 : 1 0 4 - 1 2 3 . Rae , A . L . ( 1 9 8 2 ) . Ob j e c t ives i n s h e e p b r e ed i ng . P r oc . l s t Wo r ld Congr e s s o f S h e ep and Be e f Ca t t l e Breed i n g , Vo l I I : 2 9 - 3 7 . Ra l p h , C . L . ( 1 9 8 4 ) . P i nea l bod i e s a nd t h e r mo r egu lat i on . I n : 2 3 2 " The p i nea l g la nd '' . Ed . R . J . Re i te r , Rave n P r e s s , N . Y . , pp . 1 9 3 - 2 2 0 . Ra t t ray , P . V . ( 1 9 7 7 ) . Nutr i t i on and r e pr oduct i ve e f f i c i e ncy . Cha pter 2 1 , I n : " R epr od uc t i o n i n d ome s t i c a n i ma l s " . Eds . H . H . Co l e a nd P . T . Cupps , pp . 5 5 7 - 5 7 6 . Rava u l t , J . P . ( 1 9 7 6 ) . P r o la c t i n i n the ram : seas o na l va r i a t i ons i n t h e c o nc e n t ra t i on o f b l o od p l asma f r om b i r t h unt i l 3 yea r s o ld . Ac ta Endoc r i no l og i ca 8 3 : 7 2 0 - 7 2 5 . Rava u l t , J . P . and R . O r tavan t ( 1 9 7 7 ) . L i ght c ont r o l o f pr o lact i n s e c r e t i o n i n s he e p . Ev idence f o r a phot o i nduc i b l e phase d u r i ng a d i ur n a l r hythm . Anna l e s de B i o l o g i e e t An ima l e s B i ochem i s t r i e , B i ophys i que . 1 7 : 4 5 9 - 4 7 1 . Rava u l t , J . P . , F . Ma r t i na t - B o t t e , R . Mauget , N . Ma r t i na t , A . Locate l l i a nd F . Ba r i t e au ( 1 9 8 2 ) . I n f l ue nce o f t he durat i on o f dayl i ght o n pr o lact i n s e c r e t i on i n t h e p i g : h our ly r hythm i n ova r i e c t omi zed f ema l e s , mon t h ly va r i a t i on i n d ome s t i c ma l e s and f ema l e s a nd w i l d s t ra i ns dur i ng t he yea r . B i o l ogy o f R epr od uc t i on 2 7 : 1 0 8 4 - 1 0 9 7 . Re e ve , E . C . R . and F . W . R o be r t s o n ( 1 9 5 3 ) . Factor s a f f e ct i ng mu l t i p l e b i r t hs i n s he e p . An ima l B r e ed i ng Abs t racts , 2 1 : 2 1 1 - 2 2 4 . Re i s , P . J . ( 1 9 6 5 ) . Var i a t i o ns i n the s u l phur c o n t e n t o f wo o l . I n : ' B i o l ogy o f t he s k i n a nd ha i r gr owt h ' . Eds . A . G . Lyne a nd B . F . S h o r t , Angus a nd R obe r t s o n , Sydney , pp . 3 6 5 - 3 7 6 . Re i s , P . J . ( 1 9 6 5 ) . The gr owth a nd compos i t i on o f woo l . I I I . Va r i a t i ons i n s u l phur c o n t ent o f woo l . Aus t ra l ia n J ourna l o f B i o l og i ca l S c i e nce 1 8 : 6 7 1 - 6 8 7 . R e i s , P . J . ( 1 9 6 7 ) . T he g r owt h a nd c ompo s i t i on o f woo l I V . The d i f f e r e nt i a l r e s po n s e o f gr owt h a nd o f s u l phur c o ntent o f wo o l t o the l e ve l o f s u l phur-conta i n i ng ami no a c i ds g i ve n aboma sa l l y . Aus t ra l i an J o ur na l o f B i o l o g i c a l S c i e nce 2 0 : 8 0 9 - 8 2 5 . Re i s , P . J . ( 1 9 6 9 ) . The gr owth a nd compos i t i on o f wo o l V . S t i mu lat i o n o f wo o l g r owt h by the abomasa l admi n i s t rat i on o f va ry i ng amounts o f case i n . Aus tra l i an J o urna l o f B i o l o g i ca l S c i e nce 2 2 : 7 4 5 - 7 4 9 . Re i s , P . J . ( 1 9 7 9 ) . E f f e cts o f ami no ac i d s on the gr owth a nd pr ope r t i e s o f woo l . I n : " P hys i o l og i ca l and Env i r onme nta l L im i tat i ons t o Wo o l Gr owth " , Eds . J . L . B lack a nd P . J . Re i s , U . N . E . Pub l i s h i ng Un i t , Armida l e , N . s . w . I pp . 2 2 3 - 2 4 2 . Re i s , P . J . and P . G . S c h i nc k e l ( 1 9 6 la ) . S ome e f f e c t s o f 2 3 3 s u l phu r - c o n ta i n i ng am i no ac ids o n t h e gr owt h a nd c ompo s i t i on o f woo l . Aus tra l i a n J o u r na l o f B i o l og i ca l S c i e nc e 1 6 : 2 1 8 - 2 3 0 . Re i s , P . J . a nd P . G . S ch i nck e l ( 1 9 6 l b } . N i tr ogen ut i l i za t i o n and wo o l pr oduct i o n by s he e p . Aus t ra l ian J o u r na l o f Agr i c u l t ur a l R esearch 1 2 : 3 3 5 - 3 5 2 . R e i s , P . J a nd P . G . S c h i nck e l ( 1 9 6 4 ) . T he g r owth a nd c ompo s i t i on o f wo o l I I . The e f f e c t o f case i n , ge l a t i n , and s u l phur c onta i n i ng am i n o a c i d s g i ve n pe r abomasum . Aus t r a l i a n J o u r na l o f B i o l og i ca l S c i e nce 1 7 : 5 3 2 - 5 4 7 . Re i s , P . J . a nd D . A . Tunks ( 1 9 6 8 ) . R epr oduca b i l i ty o f i nd i v i dua l d i f f e r e nces i n t h e s u l p h u r cont e n t o f wo o l gr own by Me r i no s he e p . P r oce e d i ngs o f the Aus tra l i an S oc i e ty o f An i ma l P r od uct i on 7 : 4 0 2 - 4 0 6 . Re i s , P . J . , D . A . Tunk s a nd L . F . S ha r ry ( 1 9 7 3 } . P lasma ami n o a c i d pa t t e r ns i n s he e p r e c i e v i ng a bomasa l i n f us t i ons o f me t h i o n i ne a nd cys t i ne . Aus t ra l i a n J o u rna l o f B i o l og i ca l S c i e nce 2 6 : 6 3 5 - 6 4 4 . R e i s , P . J . a nd O . B . Wi l l iams ( 1 9 6 5 ) . Va r i a t i o ns i n t he s u l ph u r c o n t e nt o f wo o l f r om Me r i no s h e ep o n two semi ? a r i d g r a s s l a nds . Aus t r a l ian J o u r na l o f A.:Jric.v.\tura.\ K?5?e.a r>c.h 1 6 : 1 0 1 1 - 1 0 2 0 . Re k l e ws ka , B . ( 1 9 7 4 ) . A n o t e o n t he e f f e c t o f b ov i ne s oma t o t r oph i c h o rmone o n wo o l p r oduct i on i n gr owi ng lambs . An i ma l P r od uct i o n 1 9 : 2 5 3 - 2 5 5 . Re l k i n , R . ( 1 9 8 3 ) . P i nea l -ho rmone i nt e r ac t i ons . I n ' Th e P i nea l g la nd ' . Eds . R . Re l k i n , E l s e v i e r B i omed i ca l N Y , pp . 2 2 5 - 2 4 6 . R i c ourde a u , G . , M . R . B lanc and L . B od i n . ( 1 9 8 4 } . T eneurs p la sma t i qu es e n F S H e t LH d e s agne a u x ma l es e t f eme l l e s i s sus d e be l i e r s Lacaune pr o l i f i gues e t non? pr o l i f i q ues . Ge ne t i gue , S e l e c t i o n , Evo lut i o n , 1 6 : 1 9 5 - 2 1 0 . R i ve i r e , J . E . , F . R . Enge l hardt and J . S o l omon ( 1 9 7 7 ) . The r e l a t i o ns h i p o f thyr ox i ne a nd c or t i s o l t o t h e mou l t o f t h e ha r bou r s e a l ( Ph oca v i t u l i na ) . G e ne ra l a nd Compa r a t i ve Endoc r i n o lgy 3 1 : 3 9 8 - 4 0 8 . R oba rds , G . E . and K . D . Atk i ns ( 1 9 7 6 ) E f f i c i e ncy o f wo o l p r oduc t i o n o f hogge t e we s f r om a Me r i no f l o c k s e l e c t e d f o r f e r t i l i ty . P r oc e ed i ngs o f t h e Aus tra l i a n S o c i e ty o f An i ma l P r od uct i o n 1 1 : 2 9 - 3 2 . R obard s , G . E . and W . A . Pa t t i e ( 1 9 6 7 ) S e l ec t i o n f o r c r i mp f r e q ue ncy i n woo l o f Me r i n o s he e p . I . D i r e c t r e s pons e t o s e l e c t i on . Aust ra l i an J ou r na l o f Expe r ime nta l Agr i c u l t u r e a nd An ima l Hus ba nd ry 7 : 5 5 2 - 5 5 8 . 2 3 4 R o bards , G . E . , C . H . Dav i s a nd D . G . Sav i l l e ( 1 9 7 6 ) S k i n f o l d s a nd Me r i n o b r e e d i ng . 9 . E f f i c i e ncy o f c onve r s i o n o f f o od t o woo l . Aus t ra l i a n J o urna l o f Expe r i me nta l Agr i c u l t u r e and An i ma l H u s ba nd ry 1 6 : 3 6 1 - 3 6 6 . R o bards , G . E . , A . J . W i l l iams and M . H . R . H unt ( 1 9 7 4 ) . S e l e c t i on f or c r i mp f r equency i n t h e wo o l o f Me r i no s h e ep I I . E f f i c i e ncy o f conve rs i o n o f f o od t o wo o l . Aus tra l i a n J o u r na l o f Exper ime nta l Agr i cu l t u r e a nd An ima l H us band ry 1 4 : 4 4 1 - 4 4 8 . R o be r t s , N . F . , J . F . P . Jame s a nd V . D . B urgmann ( 1 9 6 0 ) . T ende r ne s s i n f l e e ce woo l . J ourna l o f the T e x t i l e I ns t i t u t e 5 1 : T9 3 5 - 9 5 2 . R o b i ns o n , J . E . , N . L . Wayne a nd F . J . Ka r s c h ( 1 9 8 5 ) . R e f ract o r i ne s s t o i nh i b i t ory dayl e ngths i n i t i a t e s the breed i ng s e a s o n o f t h e S u f f o l k e we . B i o l ogy o f Repr oduct i on 3 2 : 1 0 2 4 - 1 0 3 0 . R odway , R . G . ; S w i f t , A . D . ; Nowak , R . ; Sm i t h , J . A . a nd Padw ic k , J . A . ( 1 9 8 5 ) . P lasma c o ncen t ra t i ons o f me l a t on i n a nd t h e o ns e t o f pube r ty i n t he f ema l e l amb . An ima l R e pr o d uc t i on S c i e nce 8 : 2 4 1 - 2 4 6 . R o e , R . , W . H . S o ut hc o t t , H . N . Tur ne r ( 1 9 5 9 ) . Gra z i ng manageme n t o f nat i ve pas ture i n t h e N ew Eng l a nd r e g i on o f N . S . W . 1 . Pas tu r e a nd s he e p product i on w i t h s pec i a l r e f e r e nce t o g ra z i ng a nd i nt e r na l paras i t e s . Aus t ra l i a n J o u rna l o f Agr i c u l t ura l Res earch 1 0 : 5 3 0 - 5 5 4 . R o l lag , M . D . a nd G . D . N i swe nder ( 1 9 7 6 ) . Rad i o i mmunoas say o f s e r um c o nce n t ra t i o n s o f me laton i n i n s he e p e xposed t o d i f fe r e nt l i g h t i ng r eg i mes . Endocr i no l ogy 9 8 : 4 8 2 - 4 8 9 . R o s e J . , F . S t o rms ha k , J . O ld f i e ld , J . Ada i r ( 1 9 8 4 ) . I nduct i on o f w i nt e r f ur gr owt h i n m i n k ( Mus t e la v i s o n ) w i t h me l a t o n i n . J o u r na l o f An ima l S c i e nce 5 8 : 5 7 - 6 1 . R o s s , D . A . ( 1 9 6 0 ) . S ta p l e s t r e ngth I . The measu r eme n t o f s ta p l e s t r e ngt h . N ew Z e a land J ou rna l o f Agr i c u l t ura Research 3 : 5 0 3 - 5 2 5 . R oss , D . A . ( 1 9 6 1a ) . S ta p l e s t r ength I I . S ome fac t o r s a f f ect i ng t he mea s ur eme n t o f s t ap l e s t r e ngt h . New Z e a l and J o ur na l o f Agr i cu l t ura l Re s earch 4 : 5 7 - 7 1 . R oss , D . A . ( 1 9 6 1 b ) . S t a p l e s t r ength I I I . Var i a t i ons t hr ough the wo o l s e l l i ng s e a s o n . New Z e a land J o u r na l o f Agr i cu l t ura l R e s e a r c h 4 : 5 2 3 - 5 3 7 . R oss , D . A . ( 1 9 6 1 c ) . B i o l og i ca l aspects o f the s u l phur content o f R omney wo o l . Pr oceed i ngs o f t h e N ew Z e a land S oc i e ty of An i ma l P r od uc t i o n 2 1 : 1 5 3 - 1 6 5 . 2 3 5 R o s s , D . A . ( 1 9 6 2 } . Fo l l i c l e p r oduc t i v i ty a nd wo o l p r oduc t i o n i n R omney ewe s . Aus t r a l i a n J ou r na l o f Agr i cu l tu ra l R e s earch 1 3 : 9 2 4 - 9 4 2 . R os s , D . A . ( 1 9 6 4 } . Woo l pr oduct i on a nd s u l phur c o n t e n t . N e w Z e a l and J our na l o f Agr i c u l tu ra l R esearch 7 : 6 6 3 - 6 6 5 . R os s , D . A . ( 1 9 6 5 } . Woo l gr owth o f t h e New Z e a l and R omney . N ew Z e a land J o u r na l o f Agr i c u l tura l R esearch 8 : 5 8 5 - 6 0 1 . R os s , D . A . ( 1 9 8 2 } . S t ap l e s t r e ngt h , s t ap l e l e ngth , f i br e l e ng t h a nd process i ng . Woo l 7 ( 4 } : 1 2 - 1 5 . R o s s , D . A . ( 1 9 8 4 ) . Measureme n t o f s t a p l e s t r e ngth i n N ew Z e a l a nd . L i nco l n Co l l e ge Wo o l Bu l l . N o . l . Re po r t o f a s em i nar on s tap l e s t r e ngt h . Eds . D . A . Ross a nd L . F . S t o ry , pp . 1 5 - 2 8 . R o s s , D . A . , R . L . B r a t t a nd L . F . S t o ry ( 1 9 6 1 ) . The e f f e c t o f s ta p l e s t r ength o n card i ng a nd c omb i ng . J o u r na l o f t h e Text i l e I ns t i t u t e 5 1 : T9 0 7 - 9 2 1 . R o s s , D . A . , G . A . 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W . ; Dur i ng , C . a nd We bby , R . W . ( 1 9 8 1 ) . E f f e c t o f gra z i ng ma nageme n t o n hogge t f l e e c e character i s t i cs . P r o c e ed i ngs o f t he New Z e a l and S oc i e ty o f An i ma l P r oduct i o n 4 1 : 1 2 8 - 1 3 2 . Tama r k i n , L . , W . K . We s t r om, A . L . Hami l l a nd B . D . G o l dman ( 1 9 7 6 ) . E f f e c t o f me l a t o n i n o n the r e ? r oduct i ve s ys te ms o f ma l e a nd f ema l e Syr i an hams t e r s : A d i urna l r hythm i n s e ns i t i v i ty t o me lat o n i n . E nd oc r i no l ogy 9 9 : 1 5 3 4 - 1 5 4 1 . Tama r k i n , L . , c . w . H o l l i st e r , N . G . L e f e bvr e a nd B . D . G o l dma n ( 1 9 7 7 ) . Me l aton i n i nduc t i o n o f g onada l qu i e sce nce i n p i ne a l e c t omi zed Syr i a n hams t e r s . S c i e nce 1 9 8 : 9 5 3 - 9 5 5 . TEAM f i na l r e ?o r t ( 1 9 8 5 ) . Re ? or t t o t h e wo o l measu r eme nt r e s e a r c h adv i s o ry c omm i t t e e o f t he Austra l i a n wo o l c o r po r a t i on . T e rgu i , M . , C . De l ou i s and R . O r tava n t ( 1 9 8 4 ) . P h o t o ?e r i od i sm a nd ho rmon e s i n s h e e ? a nd goats . I n : ' Ma n i pu la t i on o f gr owth i n f a rm a n i ma l s ' . Eds . J . F . R oche , D . O ' Ca l lagha n , Ma r t i nus N i j ho f f , p? . 2 4 6 - 2 5 7 . Te r n o ut h , J . H . a nd A . W . Bea t t i e ( 1 9 7 0 ) . A n o t e on t h e vo l untary f ood c o nsumpt i o n a nd the s od i um- ? o ta s s i um r a t i o o f s he e p a f ter s hea r i ng . An i ma l P r oduct i on 1 2 : 3 4 3 - 3 4 6 . Ther i e z , C . a nd J . Ro uge o t ( 1 9 6 2 ) . I n f l ue nce o f thyr o i d h o rmon e s o n the growth i n l e ng t h o f woo l f i br e s . Anna l e s de B i o l og i e , An i ma l e s , B i ochemi que 2 : 5 - 1 1 . T h i mo n i e r , J . , J . P . Rava u l t , R . O r tavan t ( 1 9 7 8 ) . P la sma pr o la c t i n va r i a t i ons a nd cyc l i c ovar i a n act i v i ty i n ewe s s ubmi t ted t o d i f f e re n t l i ght r e g i mes . Anna l e s d e B i o l og i e , An ima l e s , B i ochem i que , B i ophys i que 1 8 : 1 2 2 9 . Thun , R . , E . Egge nbe r ge r , K . Z e r o b i n , T . L usche r a nd W . Ve t t e r ( 1 9 8 1 ) . Twe nt y- f our h o u r s e c r e t o r y pat t e r n o f c o r t i s o l i n t h e bul l : Ev i d e nce o f e p i s od i c s e c r e t i o n a nd c i r ca d i an r hythm . Endocr i no l ogy 1 0 9 : 2 2 0 8 - 2 2 1 6 . T i e r ne y , M . L . ( 1 9 7 6 ) . Gene t i c a s pe c t s o f pube r ty i n Me r i no e we s . I n : ' S h eep breed i ng ' . P r o c e ed i ngs o f t h e 1 9 7 6 I n t e r na t i o na l c o ngress , Mu r e s k a nd Pe r t h , W . A . , Eds . G . J . Tome s , D . E . Robe r t s o n a nd R . J . L i ght f oot , pp . 3 2 2 - 3 2 9 . Tuc k e r , H . A . ( 1 9 8 2 ) . S easona l i ty i n ca t t l e . Ther i og e n o l ogy 1 7 : 5 3 - 7 1 . Tur n e r , H . N . ( 1 9 6 2 ) . B r eed i ng Me r i n o s he e p f or mu l t i p l e 2 4 1 b i r t hs . Wo o l Tec h n o l ogy a nd S he e p B r e ed i n g , 9 : 1 9 - 2 4 . Tur n e r , H . N . ( 1 9 6 8 ) . The e f f e c t o f s e l e c t i on o n l amb i ng r a t e s . P r oc e ed i ngs o f a Sympos i um o n the P hys i o l ogy o f R eproduct i o n i n S he e p , Ok l a homa S ta t e Un i ve r s i ty , S t i l l wa te r , OK . , July 2 6 - 2 7 , 1 9 6 8 . pp . 6 7 - 9 3 . Turne r , H . N . ( 1 9 6 9 ) . Ge ne t i c i mpr oveme n t o f r e p r oduct i ve r a t e i n s h e e p . An ima l B r e ed i ng Abs t racts 3 7 : 5 4 5 - 5 6 3 . Turn e r , H . N . ( 1 9 7 2 ) . Ge ne t i c i nt e r ac t i on s be twe e n woo l , mea t a nd mi l k p r o duc t i o n i n s he e p . An i ma l Breed i ng Abs t ract s 4 : 6 2 1 - 6 3 4 . Turne r , H . N . , M . G . B r o k k e r a nd C . H . S . D o l l i ng ( 1 9 7 0 ) . Re s po n s e t o s e l e c t i o n i n Aus t ra l i a n Me r i n o s he e p . I I I . S i ng l e c ha r a c t e r s e l e ct i on f or h i g h a nd l ow va l ues o f wo o l we i gh t a nd i ts c omponents . Aus t r a l i a n J o ur na l o f Agr i cu l tura l R e s earch 2 1 : 9 5 5 - 9 8 4 . Turne r , H . N . C . H . S . D o l l i ng a nd J . F . K e nnedy ( 1 9 6 8 ) R e sponse t o s e l e ct i o n i n Aust ra l i an Mer i no s he e p . I . S e l e ct i on f o r h i g h c l ea n wo o l we i ght w i t h a c e i l i ng o n f i bre d i ame t e r a nd d eg r e e o f s k i n wr i nk l e . R e sponse i n wo o l a nd body c ha r a c t e r i s t i cs . Aus tra l ia n J o urna l o f Agr i cu l tura l R e s earch 1 9 : 7 9 - 1 1 2 . Turne r , H . N . a nd N . J ac k s o n ( 1 9 7 8 ) . R e s p o nse t o s e l e c t i o n i n Aus t ra l i a n Me r i no s h e ep . VI I I . Fur t h e r r e s u l t s on s e l ec t i o n f o r h i gh c l ean woo l we i gh t wi th a t te nt i o n t o q ua l i ty . Aus tra l i a n J o ur na l o f Agr i c u l t ura l R e s earch 2 9 : 6 1 5 - 6 2 9 . U nd e rwood , H . ( 1 9 8 4 ) . The p i ne a l and c i r cad i an r hythms . I n : " The p i nea l g la nd " , Ed . R . J . Re i te r , Rave n P r e s s , N . Y . pp . 2 2 1 - 2 51 . Ve s e l y , J . A . and Sw i e r s tra , E . E . ( 1 9 8 6 ) . R eproduc t i ve pa rame te r s o f c r o s sbr ed ewe l ambs s i r ed by R omanov , F i n n , D o r s e t a nd We s t e r n Range rams . Jour na l o f An i ma l S c i e nce 6 2 : 1 5 5 5 - 1 5 6 2 . Wa l lace , A . L . C . ( 1 9 7 9 ) . The e f f ec t o f h o rmones o n wo o l gr owth . I n : " Phys i o l og i ca l a nd Env i r o nme nta l L i mi tat i ons t o Wo o l G rowth " , Eds . J . L . B l a c k a nd P . J . Re i s , U . N . E . P ub l i s h i ng Un i t , Arm i da l e , N . S . W . , pp . 2 5 7 - 2 6 8 . Wa l lace , L . R . ( 1 9 5 8 ) . B r e ed i ng Romneys f or be t t e r lamb i ng prece n tage s . N ew Z e a land Journa l o f Ag r i c u l t u r e 9 7 : 5 4 5 - 5 5 0 . Wa l lace , L . R . ( 1 9 6 4 ) . The e f f e ct o f s e l e c t i o n f or f e r t i l i ty o n l amb a nd wo o l pr oduct i on . Pr o c e ed i ngs o f t he Rua k ura f a rme r ' s c o n f e r e nce p . 2 5 - 2 6 . 2 4 2 Wa rd , K . A . a nd S . E . Kasma r i k ( 1 9 7 9 ) . S t ud i e s on t h e i n v i t r o me tabo l i sm o f 3 H - c or t i s o l a nd 3 H - Oestrad i a l by s h e e p s k i n a nd wo o l r o o t s . Aus t ra l i a n J ourna l o f B i o l og i ca l S c i e nc e 3 2 : 1 9 7 - 2 0 4 . Wa t s o n-Wh i tmyre , M . a nd M . H . S te t s o n ( 1 9 8 3 ) . S imu la t i o n o f p eak p i ne a l me l a t o n i n r e l ea s e r e s t o r e s s e ns i t i v i ty t o e ve n i ng me laton i n i n j e c t i o ns i n p i ne a l ectomi z ed hams t e r s . End oc r i n o l ogy 1 1 2 : 7 6 3 - 7 6 5 . We s t o n , R . H . ( 1 9 5 9 ) The e f f i c i e ncy o f woo l pr oduc t i on o f gra z i ng Me r i n o s he e p . Aus t ra l i a n J ournal o f Agr i c u l tura l R esearch 1 0 : 8 6 5 - 8 8 5 . We s t o n , R . H . ( 1 9 7 0 ) . Vo l un ta ry c o n sumpt i on o f l ow qua l i ty r o ughage by s h e ep dur i ng c o ld e xposur e . Aus t r a l i an J o u r na l o f Expe r i me nt a l Agr i c u l tu r e An ima l Husba ndry 1 0 : 6 7 9 - 6 8 4 . We t tema n n , R . P . and H . A . Tuck e r ( 1 9 7 4 ) . R e lat i ons h i p o f amb i e nt tempe rature t o s e r um p r o lact i n i n he i f e r s . P r oce ed i ngs o f t he S oc i e ty o f Expe r i me nta l B i o l ogy a nd Med i c i ne 1 4 6 : 9 0 8 . Whe a t l ey , I . S . , A . L . C . Wa l la c e , J . M . Bas s e t t ( 1 9 6 6 ) . Me ta bo l i c e f f e c ts o f o v i ne g r owth h o rmone i n s h e e p . J ou rna l o f Endocr i n o l ogy 3 5 : 3 4 1 - 3 5 3 . Whe e l e r , J . L . , T . F . Rea rd on a nd L . J . Lambourne ( 1 9 6 3 ) . The e f f e ct o f pas tu r e ava i l a b i l i ty a nd s h ear i ng s t r e s s o n h e r bage i ntake o f gra z i ng s he e p . Aus t ra l i an J ourna l o f Agr i cu l tura l R esearch 1 4 : 3 6 4 - 3 7 2 . Whe e l e r , J . L . , D . A . Hedges a nd C . Mu lcahy ( 1 9 7 7 ) . The us e o f dye band i ng f or measur i ng wo o l pr oduct i on a nd f l e e c e t i p wea r i n rugged a nd unr ugged s he e p . Aus t ra l ia n J o u r na l o f Agr i cu l tura l R e s ea rch 2 8 : 7 2 1 - 7 3 5 . Wh i te ly , K . J . a nd Jack s o n , N . ( 1 9 8 2 ) . B r e ed i ng f o r a ppa r e l wo o l . P r oceed i ngs o f t he 1 s t Wor ld c ongr e s s o n S he e p a nd Be e f Ca t t l e B r e ed i ng , Vo l I : 4 7 - 5 5 . W i c k ham, G . A . ( 1 9 6 8 ) . B r e a k a nd t e nd e r ne s s i n wo o l . S h e e p Fa rm i ng Annua l 6 8 : 7 3 - 7 8 . W i c k ham, G . A . ( 1 9 7 0 ) . Wo o l g r owth i n r e lat i on t o s u l phur ? c on ta i n i ng ami n o ac id admi n i s t ra t i on t o s h e e p . P r oce ed i ngs o f t he N ew Z e a land S oc i e t y o f An i ma l P r od uct i o n 3 0 : 2 0 9 - 2 1 5 . W i c k ham, G . A . a nd MacPhe r s o n , A . W . ( 1 9 8 5 ) . A r ev i ew o f t h e i mpor tance o f wo o l t r a i t s as ge ne t i c improveme nt o b j e c t i ve s a nd s e l e ct i o n c r i t e r i a f o r New Z e a land Romney she e p . P roceed i ngs o f t he Ne w Z ea land S oc i e ty o f An i ma l P r oduct i on 4 5 : 2 0 3 - 2 0 8 . Wi ldma n , A . B . ( 1 9 5 7 ) . P h o t o pe r i od i c i ty a nd wo o l g r owt h i n R omney r ams a nd we t he r s . Na t u r e 1 8 0 : 2 9 6 - 2 9 7 . 2 4 3 W i l k s , S . S . ( 1 9 4 6 ) . S amp l e c r i te r i a f o r t e s t i ng e q ua l i ty o f means , e q ua l i ty o f va r i ance s , and e q ua l i ty o f c ovar i a nce i n a n o rma l mu l t i va r i a t e d i s t r i but i on . Anna l s o f Ma t h . S ta t . 1 7 : 2 5 7 - 2 8 1 . W i l l i ams , A . J . ( 1 9 6 4 ) . The e f fe c t o f d a i l y pho t o pe r i od o n woo l gr owt h o f Me r i n o r ams s ub j e c t e d t o unr e s t r i c ted a nd r e s t r i c t ed f e e d i ng r e g i me s . Aus t r a l i an J o ur na l o f Expe r i me nta l Agr i cu l t u r e and An i ma l Hus babdry 4 : 1 2 4 - 1 2 8 . W i l l i ams , A . J . ( 1 9 6 6 ) The e f f i c i e ncy o f c o nve r s i on o f f e e d t o woo l d u r i ng l i mi t ed a nd u n l i m i t ed f eed i ng o f f l oc k s s e l ected o n c l ea n f l e e ce we i ght . Aus t r a l i a n J o u rna l o f Expe r i me nta l Agr i cu l t u r e and An i ma l Husba nd ry 6 : 9 0 - 9 5 . W i l l i ams , A . J . ( 1 9 7 3 ) Me tabo l i s m o f Cys t i ne by Me r i n o s h e e p Ge ne t i ca l l y D i f fe r e nt i n Woo l P r od uc t i on . I I I . The i nc o rpora t i on o f rad i oact i v i ty i nt o woo l f i br e s d ur i ng a nd a f t e r i nt r ave nous i n f us i o ns o f l - [ 3 5S ] cys t i ne a nd i ts r e l a t i o n s h i p t o wo o l gr owth and e f f i c i e ncy o f c onve r s i o n o f f o od i n t o woo l . Aus t ra l ian J o u rna l o f B i o l og i ca l S c i e nce 2 6 : 4 6 5 - 4 7 6 . W i l l i ams , A . J . ( 1 9 7 3 ) Me tabo l i sm o f Cys t i ne by Me r i no s he e p Gene t i ca l ly D i f f e r e nt i n Wo o l P r od uc t i on . I V . Ra t e s o f e nt ry o f cys t i ne i nt o p la sma , mea su r ed wi th a s i ng le i nt rave nous i n j e c t i on o f L - [ 3 5 S ] cys t i ne , a nd t he s ubseque nt i nc or pora t i on o f 3 5S i nt o wo o l f i bres . Aus t ra l i a n J o u r na l o f B i o l og i ca l S c i e nce 2 9 : 5 1 3 - 5 2 4 . W i l l i ams , A . J . ( 1 9 7 6 ) . The e f f i c i e ncy o f wo o l pr oduct i o n . R epo r t t o t h e Aust ra l i a n Wo o l C o rp o ra t i on . 5 3 pp . W i l l i ams , A . J . ( 1 9 7 9 ) . S pe c u la t i o n o n t h e b i o l og i ca l mec han i sms r e s pons i b l e f or gene t i c va r iat i on i n t h e rate o f wo o l g r owt h . I n : " P hys i o l og i ca l a nd Env i r onmenta l L i mi ta t i ons t o Wo o l G r owt h " , Eds . J . L . B lack a nd P . J . Re i s , U . N . E . P ub l i s h i ng Un i t , Armida l e , N . S . W . , pp . 3 3 7 - 3 5 4 . W i l l iams , A . J . ( 1 9 8 4 ) . Ea r l y e v i d e nce o f a d i f f e r e nce i n woo l p r oduc i ng a b i l i ty . P r oceed i ngs o f the Aus t ra l i a n S oc i e ty o f An i ma l P r oduc t i o n 1 5 : 7 7 0 . W i l l i ams , A . J . ( 1 9 8 7 ) . P hys i o l og i ca l c onse quences o f s e l e c t i o n f o r i ncreased f l e e ce we i ght . !? r o e . o f t h e Aus tra l i a n Wo o l B oard c o n f e r e nce on " The a pp l i ca t i o n o f s he e p b r e ed i ng a nd ge ne t i cs t o the s heep and wo o l e nt e r pr i s e s i n Aus t ra l i a " . W i l l i ams , A . J . , R . A . L eng a nd S . K . S t e phe ns on ( 1 9 7 2 ) Me tabo l i sm o f cys t i ne by Me r i n o s he e p gene t i ca l ly 2 4 4 d i f fe r e n t i n woo l p r oduc t i on . I . Compa r i s on o f t h e e nt ry r a tes o f cys t i ne i n s h e ep f r om f l oc k s s e l e c t i ve ly bred f o r h i gh a nd l o w f l e e cewe i ght . Aus t ra l i a n J o ur na l o f B i o l og i ca l S c i e nce . 2 5 : 1 2 5 9 - 1 2 6 8 . W i l l i ams , A . J . a nd H . P . M i l l e r ( 1 9 6 5 ) . The vo lun ta ry f e ed i ntake o f s he e p g e ne t i ca l ly d i f f e r e nt i n wo o l pr oduct i o n . Aus t ra l i a n J o ur na l o f Expe r i me nta l Agr i cu l t u r e a nd a n i ma l Husba ndry 5 : 3 8 5 - 3 8 9 . W i l l i ams , A . J . , G . E . R o ba rd s a nd D . G . S av i l l e ( 1 9 7 2 ) Me tabo l i sm o f cys t i ne by Me r i no s he e p gene t i ca l ly d i f f e r e n t i n wo o l p r o d uc t i o n I I . R esponses i n wo o l gr owt h t o a bomasa l i n f us i ons o f L - cys t i ne o r DL? me t h i on i ne . Aus t r a l i a n J o ur na l o f B i o l og i ca l S c i e nce 2 5 : 1 2 6 9 - 1 2 7 6 . W i l l i ams , A . J . a nd R . J . W i n s t o n ( 1 9 6 5 ) . R e l a t ive e f f i c i e nc i e s o f c o nve r s i on o f f eed t o wo o l at t h r e e l eve l s o f n u t r i t i on i n f l oc ks gene t i ca l ly d i f f e r e n t i n wo o l product i o n . Aus t r a l i a n J our na l o f Expe r i me nta l Agr i cu l t ur e a nd An i ma l Husba ndry 5 : 3 9 0 - 3 9 5 . W i l l i ams , A . J . a nd R . J . W i ns t o n ( 1 9 8 7 ) A s t udy o f t he character i s t i cs o f wo o l f o l l i c l e a nd f i bre i n Me r i n o s he e p gene t i ca l ly d i f f e r e n t i n wo o l pr oduct i on . Aus t ra l i a n J o u r na l o f Agr i cu l tur a l Research 3 8 : 7 4 3 - 7 5 6 . W i l l iams , 0 . 8 ( 1 9 6 4 ) . A r e l a t i o ns h i p be twe e n f or age ava i l a b i l i ty a nd woo l g r owt h rate f or h i gh a nd l ow pr oduc i ng s he e p . P r o c e e d i ngs o f the Aus t ra l i a n S oc i e ty o f An ima l P r oduct i on 5 : 2 8 0 - 2 8 3 . W i l l iams , O . B . a nd P . G . S c h i nc k e l ( 1 9 6 2 ) . S easona l va r ia t i ons i n wo o l g r owth a nd l i vewe i ght i n s eve r a l e nv i r o nme nts . P r o c e ed i ngs o f the Aus t r a l ian S o c i e ty o f a n ima l P r od uc t i on 4 : 3 8 - 4 5 . W i l l iams , 0 . 8 . a nd H . S u i j d e nd o r p ( 1 9 6 8 ) . Wo o l g r owth o f we thers gra z i ng Aca c i a a ne ura -Tr i od i a punge ns savanna a nd ewes gra z i ng t r i od i a punge ns hummoda g rass s t e pp e i n t h e P i l bara d i s t r i c t . W . A . . Aus t r a l ian J ou r na l o f Expe r ime nta l Agr i c u l t u r e a nd An ima l Husband ry 8 : 6 5 3 - 6 6 0 . W i l s o n , A . D . and N . L . H i hd l e y ( 1 9 6 8 ) Compar i s on o f t h e vo l untary wa t e r i n t a k e s o f s ome Aus t ra l ian Me r i no s . F i e ld S tat i on R e s e a rc h , D i v i s i on o f P l ant I ndustry , CS I RO 7 : 2 5 - 3 6 . W i l s o n , I. F . ( 1 9 3 1 ) . T he i n f l ue nce o f the p l ane o f nutr i t i o n upo n va r i o us f acto rs re lated to wo o l g r owt h . Na t i o na l Wo o l Gr owe r 2 1 : 2 3 - 2 8 . W i nk lma i e r , M . A . ( 1 9 8 3 ) . The s e a s o na l produc t i on o f moha i r f r om Angora g oa t s i n Can t e rbury . The s e s , M . Agr . S c i . , 2 4 5 L i nc o l n Co l l e ge , Ca nte rbury , N . Z . Wod z i c k a , M . ( 1 9 6 0 ) . Seas ona l var i a t i ons i n woo l g r owth a nd h e a t t o l e r a nc e o f s he e p . 1 . Woo l g r owt h . Aus t ra l i a n J ou r na l o f Agr i cu l tura l Resea r c h 1 1 : 7 5- 8 4 . Wod z i c k a - Toma s z ews k a , H . ( 1 9 6 3 ) . The e f fe c t o f s hea r i ng o n t h e appe t i te o f s he ep . 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