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 pennission of the Author. • < IA A 1L;i _'.I£ t;., ;-• t l .- I. ~ ~ \ &.6,CR/1.H~ t-:ALF,, 1.;__.i·.v;, ..:O . .,T ( i 1 N.;t. BLOAT IN RUMINANTS AS A DYSFUNCTION OF ANIMAL AND PASTURE INTERACTION. 'A consideration of the environmental and physiological factors associated with the condition,having particular reference to ' the grazing animal. D.R.Bathe. 1951. ~ Dissertation completed under joint tutorship in the departments of Plant and Dairy Husbandry, Massey College. Submitted in part fulfilment for the Plant Husbandry Section of the degree of Master of Agricultural Science,University of New Zealand. CONTENT S. "0 •• • • . . . . • • . " ". • II "" ". i:ti. Paae l 5 6 (b) Feed and em1.ronmen:tal conditions assooi.ated 'With bloat. 9 " . • • . . • • . . • • •• . . . •• • • •• 14 Feed. Oonsumpilion •• • • .. . • • .. . ". •• 15 \'+ ~ ~ l.5 (b) Herbage palatability •. .. .. . .. . •• 17 • • • • • • . . .. . • • • • •• 25 "" 86 .. . ' •• "., • * ... •• 30 . . • * •• 31 " • • • . • •• •• " • " " • • •• . • .. • " • . • •• •• • . • • • ... • • * . . " , • . $ • • "" iv. Section Page c. The Grazing Ruminant's infl·uence en :Pasture Composition • • 75 . •• . . . . . . • • . . . . . . . . . . . . . . . . . . • • . . . . . . . . . . . . . . .. . . . . • * • • & . .. .. . . . . . . . . . . .. . . . . . . . . . " . . • * . . . •• $ ' • ' • . . . . . . ~ . •• 80 •• 81 . . . . . . ' ~ ~ :a __, ;:,; C \J t< j ► ! IQ (Q '° r-1 r-f r-1 M M &4 . . • • • . . • q • . . • .. • • . $ . . . . • . . . . • . . . • " • • . . . . " • • . . . . • • . • • . . $ . • " * 0 . • . . .. . • • . . . ♦ t'.ll • • I . 5 ~ ,. I H t:1 • ~ s ffl 8 I I 8 0 orf - ! D m i i • a ~ ro P R O L O O U I. It 1s a simple and yet fundamental biological concept that one of the essential differences between plants and animals lies in their mode of nutrition. The plant is able to 1188 soil nutrienta and synthesize its nutritional requiramente in the presence of li~t b7 the process of oarbon assimilation., The animal is entirel7 dependent on thoee a;-ntheehed plant products for its 11.utri tion. ,. In this v•rT essential. difference ruminants and herbage plants assume a oommensal relationship. becoming increasingl,- interdepend.ent as systems of pasture and anlmal production inten1if¥• This relationship has become a well accepted principle in. herba,;e acrot1.0U1¥ as to appea1;" almost a. statement of the obvious. lievertheleae thw writer nr1ur:E"sli! in field tlle t two decades the ioal of plaa t p.:ro- duc tion<» of for ,..,.,,,..,,. •• ,, , with of an extended l!;ddll,l'J ... .uf11!. greater herba,;e bulk per acre, are ac.n.,1v1,mtm of the plant which have been making an. studies of the the advances b7 the us exclus as measure of t nn,11, fHl in o:r t,\! contl.'Ollable puz·pose of .roi'.llnEtn conditions 'llpi)n individual plant apecios o:i: communities. 1947 (1). - 2 - WIAIIMW.$ •4- He suggests that it is perhaps the most important faotor requiring investigation 1f a full utilization of improved paaturee 1a to be ob·tained. McMeekan 1947 (86) states that it i8 a proJ:alem which uphuiees the complent1 of these anim&l-puture 1nieractione and considers that of all of them 1 t 11 perhaps the moB t complex. So tar failure to produce 'Ute eondition 1n the field has def1e4 the more orthodox methods of experimentation. An.:}/ solut1oa however reats mere probabq upon the integrated efforts of workers 1n allied rather than 1n q one field. The crowin€ need for this t~pe ot approach 1n biological 11tud1ee is keen!¥ appreciated b¥ the writer. How•Ter, the opinion is supported that ul t1matel.y mtu1sures tor the prevention of bloat will take an agronomic form. lurther, the acroat­ ologiat sho\lld brin« that though~ to bear upoJ1 the problem which integrates those maJQ' aspects of his work de11gned to meet the needs of the cimal9 Ml attempt w1ll be made to follow that recommendation 1n this diecouree. Should this dissertation provide also & r8ferenoe baae for constructive thought whaiev$r manner of iuvestigation is adopted for the bloat probl01, its purpose will be well served. Broad.17 the subJect ma\ter will b• treated as follOWtJ:- AJ., 1'he bloat problem, its manifestations and 1no1denoe. 13:S.1. The 1n ei tu. 1nteract1ona of past,ue and ani?Ral as phenomena a.sBociated. wi ·th acute bl.oat. fart l • l'laut-oond1 tioned interaot1on!I • . BB .• 2. 'l'he 1n si\u interactions of pasture and animal a.a phenomena aseoc1ated. with acute bloat. Part II • a.1mal•oondit1oaed in. terac tions • CC... Bwninant digestion and bloat. 'lhe pb,feiologioal proceuee 1nvolTed, part1oul&l'l¥ as influena•d b¥ plant bioohemioal and :ph,ysical f'o.cto:-a, ------------- -5- .......,._------------.._______.............. .....,__,.. ..... 1s a,.1111•"""''"' , -6- ( f - - months of 1949 was instanced as being so severe bl some areas that prod­ uction fell rapidl;y, and paddocks ourTing what should have been ideal pasture for d.&117 stock were barred from grazing. Thers is a pauoitj' of. informa~on in the li'\eratue oonceming 11Ulc production loa••• from bloat, but such losses a.re in evidence. In l:o.glan4, fooldri48e 1947 (21) refera to the lowei-ing of milk production in individual cows for several wtw after recov•rT from bloat. In one dair¥ herd in lib.gland known to the writer, total milk ¥i•lds dropped from a dail7 average of 200 gal.lone before the severe outbreak: of acute bloat to 110 gallons dail¥ aTerage ilulediatel;y after and in. the ten clqa following the attack. Longman (personal.. oomnmication). Cole et al. (9) comment on the fact that Ver-Ji few 1urve7e of ihe losses attributable to bloat hB.'Ye been made. fhq quote 1'eloht Mareh, and Ttmclitfe. 1929 (22) who state that on the b&eilll of a aurv17 in Montana, cattlemen ma;r e%pect a lose from bloat ~n sweet clover paature of less than l per cent, and sheepmem about 0.5 per cent. Mo Candlish (13) reports bloat on 34 per c~t ot the daiey farma in the South 'feet of Scotland, th.ie figure being obtained in replies from 152 livestock producere. Baneon and Bo¥d 1943 (23) $ made a 1u.rve,y of l, 106 herds with nea.rq 30 000 head of cattle 1n Minneaota. A. total ot 11,205 head ware pastured on sweet clover and alfalfa in. appro:d.mate]¥ equal numbers. Yrom Mq to October 182 oases of bloat were reported. ant of these 50 were fatal. Alfalfa caused 28 deaths. eweet clover 20. Six cues of non. fatal bloat were :reported on non-legume puture. In California, :Bell and :Britton (16) · made a. surve,- over seven weea during Jul,- and .A.ugust of losses on ladino oloTer pasture. '!hese observ• ationa were coafined to six ranches with a livestock population ot 47,000 lambs and 3,200 cattle,. Twenv lambs, repreeenting about 50 per cent ot the total losses during the period, died of bloat. fwo ete•r• died from this cause.more death• from bloat occurred 1n pastures with a stand of pure clover. or with a veq high percentage of clover, and bloat was not a problem 1n certain putures covered with more than 50 per cent grasses. Bathe 1948 (24) investigated the occurrence of bloat OTer 53 dair¥ farms totalling 1.160 animals. 1n the South fest of Bngland. during the epring and s'W:llller months of 1944 and 1945. Loaaee amounted io onl,- 3 and 4 eou respeativeq 1n each 1ear, bu:\ a:aimal aud pasture aanacement - 8 - practices were seriously haapered bl" the incidence and risk of bloat. !here are a n:m1ber of reports which indica:lie the incidence ot bloat oocurr:1:ag 1a particular districts associated with envirGJ.U11.eatal conditions conduo1Te to rapid and lu■h herbace growth. (24), (13). la 5n Zeal.ad, Hawkes :Bq, Bai' of Plenv, and Maawatu districts a.re .l!W.mm; as particula.r]¥ troublesome areas, (19). (18), (93)111 Similar]¥, irrigated pasture areas especial]¥ where luoerne is cultivated are kn.own to stimulate pasturiag conditiens concluoiTe to bleat. Cole, Head, ad Began 1943 (25). Beruldsea ad Morcan 1936 (26). It is in the ,ra.rious mana,;eraat aspects of pasturi:ag uillals that the most serious inoonTeniaoe can reaul t when a.cute bloat occurs. Da.e to its in1idious nature it is difficult to predict the onset of bloat111 G,lh 1943 (27), whilst accord:1:ag to Ferga.son 1950 (28), there is no wrq emept b7 grasi:ag to tell 1f a punre will cause bloat. !his un.oer­ t&int7 neceesitates constant Tigilance of auillale at pasture which wholl.7 uneconomic practice is reported b¥ Kolntosh 1937 {29), to be res• po:asible for some stockownsrs sell:1:ag their herds due to bloat trouble. I». South Africa, Qµ.in (14L refers to the fact that stockowae:rs are com­ pelled to use luoerne i:a hq fel"ll with reau:ltant nutritiTe losses and increased productie c::u,1·1a1. The risk of bloat on lucerne pastures in Fru.ce 1~ a particular hasa.rd. to :aight grazi:ac. Davis 1950 (30). This will be appreciated when it is realised 'ihat such pastures are usual]¥ unf eaced. and free grazing is practised. Similar difficulties will be expected to preTail whe cattle are extensivel7 grazed i:a ranch:1:ag ooun.tries. (86). !he feed:1:ag of hq to aaimals prior to g.rasill.c pastures on. which there ia a bloat risk is a preTeatiTe measure generall7 reoomMeaded9 Olson 1940 (31). and practiced Oanq 1947 (32). .Apart from 'beiag un.economio, pa.rtioularly und.er all pasture s7steu of farming, there ia no conclusiTe evide•c• that such a practice is effective, although it has been olaiaed on the baeia of experimental t1Ddill.gs that feedinc hq will reduce bloat. (25 ReoomMedations are compilation of seeds mixtures in which ... vii.-,v species are reduced or excluded to leHen risk: of bl•at Butler 1949 (33). Jones, :Ba.rle a:ad Brown 1942 {34), Mead, Britton a:ad Oole. Geaeral.]¥ the 1aclusion of a =r••u•.·•·•••· percentage of grasa species - ::, - 1a reeommended; ~ie 1a an u.tirel7 eiapirical agronomic approach for which there is a. need to invea tigate experbtentalq. Legume paa ture plant, &J:I uauall~ iaplicaied in the etiology of bloat, and it ia reporte4 that bloat will not occur or is reduced on pae,.ure in which graae species 8.2:'e oYe.r .50 per cent dominaat (16}. 1'his is not '\he experience of the m-iter who bu obaerTed under le• Zeal~d oonclitiona the onaet of bloat 1D dair7 cows eeTer•lT rationed on pasture ooniaining over 80 per cent grass apee1iea. i.eports from daiqm•n in lngland indicate that 1u,vere bloat 1 incidence with fatalities has occurre4 on pasture with oooksfoot dollinam.t,loung 1947 (36), Shook 1947 (37). 'ftle exclusion ot legumes from puturee would be a practice 4etrimen~al both to herbqe production and 1011 fertilit;, and ia a reconmendation to be queatiolled, on the buie of pr•aen.t knowl•d&• concerning the incid­ eJlOe ot bloat. A number of Q'bsenere repor" the 1nc14enoe of bloat as being hid>, dlu'in« nu.sh•• of clover growth in pastures (12), {13), (14), (22), (44). Paa tu.re management to maintain. a balance between. grua and l•«um• apecies is considered to reduce bloat risk (93). ht even ,mder con.atant weather conditioJlS, this requires such hi~ skilled gru1n.g managem.en\, of'\en at difference with animal production, as to throw doubt on it■ economic value Wld.er farm oondUiou" Measure■ han been adopte4 for dai17 oow ~a•in& to re11trict pasture available at a herba&• growth stage when bloat 1s anticipated (19) and. Adams 1950 (38), tor which some aucc•ss is claimed. The s¥stem of rationed grazing to preTent bloat t"em.aina to be proved. however, an4 its effect■ on &llil!al production, and pasture composition Deed to be assessed before this s¥stea can be oonfi4entl.T reoomum4ed for general practice. It• adoption is strictl1 limit•d to intensive s~etems of pasture and manacemot. (b) ... ~ Al tW Nl,UIW ...... :..::~au, ... ~r,lKilil A:i'i'W 611 t , -- According to Muir (3) it is evident that bowel inhibito17 aubetanoea 1n forage plan.ts reach threshold lnela for the appearance of clinical e~ptome only under certain conditions of soil, weather. stage of growth, and botanical coapoai'\ion of pasture. Aoeordingl.¥ intenei•.-e eiud,y of th.ea• factors ia cons14ered even more neceat&J:¥ for the prevention of ... 10 • bloat than the identification of the toxic ag.nte whioh m&l' be involved. It ia important then to be familiar with the teed and environmental oonditiona UDder which bloat occurs., O&"tle and sheep a.t puwr• were reported to snd'fer from bloa, over eight 4eca.dea ago. Large 1863 (99)~ .Aeute bloat 414 not become a ••rioua problem according to Biborg 1795 (39). until the niddle of the eighteenth centur,. when the pasturing of cloTer aat lu.cerne becae a common practice. !rhe con.di tion is now known as a common ••4'91 to gra11:ing on. clover or o~er leguminous cropa when 111 is of\en termed. 11clo.,er 'blon" Phillipson 1942 (~. The following legominou.e crop■ baY• bee reporte4 as promoting bleat: lucerne (25) white clover (26) red cloTer ( 15) 1&41.no clover (16) sweet oloTtr (44) peae (42) an4 \refoil. (90) Other green feeds e.re know to give rise to bloat; the writer has o'b1HrTed bloat ~ daiq ca.tU• feeding Xale, g:raes law tr11111iAill&S in which legume speciee were &been'\, pasture oompriaec\ of over 80 per cent grua speciea, and in sheep grazing rape, tumip tops ,grow1ng wheat &Dd barl.,.. Shanita 1946 (41) eta.tee that bloat mq occur in eh•ep duriJlg the winter 1f tbtQ" have aoces1 ·to the gr•en o•r•al• wheat and barlq; rapid.17 growing green oereals are reported b7 Ohman 1938 (42) in .Australia to ca'Wle bloat 1n cattle. In the same c01D1tq Veeoh 1937 (43) retere to tr&velltng cattle becoming blown when e~eea green fee4 1a available, such as varie­ ga'\ed thistle ud ·the leavea of the KurraJong and willow treea. \ . The rate md et~ of growth at which herbage planis are paatured 11 reported wideq aa being u. impor'8nt contributory factor 1D the onset of bloat. Ool•.et. al. (25) claim ,o produce bloat on luoerne paa~Ul'e 1D aDl" season ot the 'J'ea:r and under T&J7ing enTirOna9Jlt&1. oon.41 tions provided the paature is in the pre-bloom stage of growth, succulent, and thick enough to allow for rapid ingesti®• Kephart 1929 (44) survqing the occurrence of bloa.t on sweet clover concluded that incidence was highest when the clover was succulent. llapid. auooulent growth of sufficient quantity would aeen io be the general pasture conditions for inducing bloat,. :Dixon 1938 (45), 1939 (46) a.nd others (41), (42). (35), (13)& i.efereno• to particular :parts of the pla».l 1s made bJ 'inin (27) who sta\es that bloa, in aheep was aaaooiated with the ravenous conaumpiion ot tlie green 1Nif¥ top~ ot luoerne. In thia connection it 1s worth noting a dairJlnan 1s observation on d&ir;y cows grazing a dominant}¥ cooke:t'oot paa·liure on which severe attacks of acute bloat were experienced: "th• cattle were curling their tongues around the top of the cocksfoot (which included \he flower). The tug then given to seTer each mouth£ul caused the cocksf oot stem to break off some wq below, with the reeul t that the unbleached oentx-e stalk was pulle4 out of its sheath, and this was con­ sumed as well as that _which the cattle had al.read¥ taken into their souths'. Young (36)41 fhe stall feeding of lucerne top• has induced severe bloat 1n cattle (15) al thOU&h lucerne tops sampled from the same putve at the 1uune time a:nd. fed in the same dr7 matter proportiou did not cause bloat. writer under New Zealand bu induced bloat in cows cutting and feeding random samples a mixed and clover species. cm. which bloat regularl~ occurred. In this manner it ia poeeible to determine the amounts of pasture oons'Ulled causing the onset of bloai. SimilarJ.i· more controlled atudiee regarding the time interTal to the oneet of the condition can be ll&de, as well as certain reactions of the rumen mo~il1t¥ qcles. The feeding of cattle on grain alone is reported. as oauaing bloat) Mead and Goss 1935 (47). In this cue continuous feeding on the saa• ration gaTe rise to the condition which could not be considered the same as acute bloat a:rbing from legume putving., Where soil conditions are conducive to lush pasture growth the risk of bloat is generall7 considered to be increased (20) (13) and it is not uncommon for the top dressing of putur•s to be implicated (8) (93). In this respect Molntoeh 1941(48) in Canada mu:e, th• oontrar7 statement that bloat is less frequently encountered on lucerne pastures where fertil• iaation and irrigation have been well maintained, than 1a the cue on neglected pastures growing on poor soil,. !hie b not in accord with the report o:f' :Be.ruldsen and Morgan (26) 1n Australia who insta:nce bloat as one of the problems associated with lush clover growth under irrigated oonditiou. Similarl1 Cole et al (25) state ~hat irrigation of luceme is necessaz1 to promote the sucoulent growth oonduci,re to the experimental production of bloat. Alwq 1927 (49) reports a wide variation in the Sulphur content of leguaes depending upon the sulphur content o! the soil .. Doak 1929 (100) 1n Bew Zeala:n.d has found that the sulphur content ot luceme is decidedl1 increased in maDl" cases b7 soil treatment with sulphur or - ·- - Sulphur oompolD148. He found that untreated lucern.e on aual7si1 showed a range in sulphur of o.26 per cent to o. 3 per cent. l.uceme leaves contained a higher percsntage of sulphur than the steu,. It what extent soil factors affect the chemical. composition of the plant aub•equentl7 of influencing the leTel/h,fdrogen sulphide gas production in the r,men is a matter for conjecture at our present state of knowledge. feather factors no doubt. have a ver1 i11portant if aom.-.hat 1nd1r♦ot influence on bloat b7 affecting thoae pasture conditions aaeooiated with a incidence" Ba.inf all and temperature variations ma.y haTe the following pria&r¥ .tfecte on a pasture. a) luoreaeH quanti t, of herb8€e per acre(! b) Conditions palatabilit¥ of the herbage. o) lnfluenoes the dominant production of Rn¥ one or group of herbace species in a pasture • Su;perimpoaed on and accentuating the influences of o) will be those in• fiuenoee resulting from the defoliation effected b¥ the grasing animal. It will follow ~at those quantit&ti.w etiological factors in bloat will operate as a) and b) reach optimum conditions in respect of the graz• ing aniraal. 'fhe qualitative f aotore will be determined by the nature of the epeoiea 4.011.inance inc) all other factors being eq:ul. Thie teatpsrature, rain:t&l.lt and pasture growth relationship as it mq be contribu'tor;;r to the incidence of bloat will be developed further in the following a•ction. At this stage it ie pertinent to not• that Oole et al (25) claim to procluce bloat at will in a:rq season on lucerne pastures where plant water requiruienta are under control b1" irrigation. :Bathe (24) in lngland . reports ihat weather favouring bureta of euoculent non fibrous herbage seems liable to cause risk of bloat during the seasous of op\unm plant growth. High rainfall effecting exoeseive growth of sweet oloTer in Iowa was considered b¥ Pamm.el 1930 (50) to giv• riae to an unusual.]J high incidence of bloat. Thie role of h'Ullidity as it mq IU'feot bloat in grazing animala 1s fa:.r from being under1tood. !he writer submits however that sevtu.•e bloat 1n dai:r¥ aattle rarely occurs in much less than one hour after pasftriJ:I& proT:l.lid. thq have not been pre fed on a bloat proToking feed. Thie is in. accord with the findings of Ool& et al (25) ad referred to~ othera. (6), (51). In view of thi.a fact 1 t is not llJU"eaaonable to assume iihat ... l~ primarilJ & herbage quantitative factor.operates to promote the onset of acute bloat whatever the aub•eqUGn.t qualitative reaction. Given \his ueumptiou, plant palata'bili'fi¥ insofar as it inf'lwmoes herbage oons'QllJ)tion 1a at:1. important factor for ooneideration. fhe role of humidit¥ then 11q 'be implicated. in its influence upon plant palatabili't¥ at thoee times when riak of bloat incidence 1s hic}l. Al.r•&dl" the oomplexit7 of those interactions in.volved in the bloat problem beoom.e apparent, hence brief reoapitula\icn wUl lend perapectiv.a to further development of the 1ubJeot. a) It is evident that acute bloat as a problem of grazing ruminants is world wid•. b) lconomio loseae fros bloat whilst difficult to measure are 1D. Such loesee are primaril¥ concerned with bloat aa & managerial problu. c) !he legume ap,ciee of herbage plant■ are those most stron~ .m,D•·~Y1,~~1~ u •~•~~,,.wi~ bloat 1u ~ It is UJlOommon for other gree !odder plate to give rise to the·aondition. d) 'l!hat de•elopment stage attaiD.ed 9f herb-«9 plants which presents conditions for opt~ conaumption ~ the animal is implicated 1n acute bloat. Under conditiona of active growth. that st&€• of plant development will be expected to fluctuate according to vu1.ations in natural and induced environaent. It will be no\ed that thi■ section has been concerned with the / more general upacta of bloat 1n rum.inants. This approach hu enabled the rHolvin.g of scattered infomation into the above generalisatione. A more particular e:ra:rnina·tion of the quHtiona poe-4. in c) and d) will :follcn,. - - BBl. ; •• • ■w •••• -• •• • • The m,m.y complex plant animal interao\ions expre1&ed 1n acute bloa\ pose numerouR problem■ for research. one to pur1uing a oloae st~ of the etiolog of bloat ia presented b7 \he d1f'ficul t,' ot producinc the condition with feeding procedure■ 111 Ae a result, the literature is seriouel.¥ limited 1n apecific reteraoe, to the 1nteraetiona in the eioro•C.Tironment exiltent. between paeture plants end the gras~ animal, as the¥ mq be ae,1ociated with bloat. 1he importance ot such interaotio~s should not be overlooked for bloat in grazinc ruminants follows upon the initial act of herbap ingestion, It is further associated with puture plants at a particular sta«e of growth and development. The writer submits '\hat according to the efficieno1 of grasing 1a tel'Jll1 of pasture intake, so will be detern11ne4 the amount of herbage entering the rumen in 8J1¥ one period of' grazing. There is evidence that gas production in the rumen is proportionatel~ related to the amount of •food conaumed Cole, Kleiber and Mead. 1942 (51), iuhburn and .Birociie 1937 (52). aud that the rate ot .,. formation varies with different foode (52), (53). It follows then that thoae differences whioh bring to bear o:n the, t.Jp• and amou:a.t of pasture herbace con1·m .. c1 1n a gi.Ten ,mit of time, ahould come under exaaination when considering the etiology of bloat. Meaeure•ent of in situ herb&&• oouumptioa, aeleotiTity ,aud knowledge of tood intake regolatoq factors in gazillg animals, are highl.7 oontroTeraial fields 8till 1n the earl7 lil'tagea of investigation. :Setter known is the etfeot on pastures of the gi-uing animal as a fa.otor of induced enviro:mnent, in so far as it influences the social order of herbage speoi•• and ther•l>l' partl7 contributes to the 00?1.ditioning of its oa diet. Whilst an attempt will be made to •xamin., such evidence in those f1el4.a as are relevant to this section, the lillitationa set 0¥ the &Taila'bilit.J­ of conclusi"t'e experimental data should be borne in mind when conjectural • 15 • upsets are oonsidere d. . of as a ic CODlWJU 1948 ( 54) in. the ooll~m'tl:n1t a.ad it re1:,p111u1 to 1ran.m~~n coa41tio:as. an.d quali t,- will ..... ,.,.,.'!!.." to cons idera.bq out the l!leuoe of active ,...,., ..... +, .. Oo:al!lequent upem. such ahan.gea will 'bet the the .Against that baclcgreund pasture will probabl7 infiuellCe the quo.tit­ ative level of rwninaat herbage co:asumption in. a given period of grazing as it Taries i:a the followi:ag ohara.cterill tics:- a.) Herbage dene i t1" and length per unit area grased. b) Palata'bilit7 of the herbage. c) Herbage quan.ti tl' and tn>• per '\l:llit area grazed. a) IWU3MHI DENSITY ARD LDG'.lR. -~---------- Seuoal T&ria.t:ioa quu.titative pasture prod.uation is a charact- eristic of ~~1uu~,~•L' gruslu.d regions. Bew Zeal.ad for -""¥"" .. the twe periods of lowest produotioA are durin.g the water and late l!lummer meaths. HudsoA et al. 1933 (55), spread. of seasonal p~od:uction being largel7 determiaei b;y climatic influac••• Various pasture plat epeciee howeTer reach their pelilc produotioa at different times within the seuonal fluotuations of total production: in tura wide quantitatiTe differe:acee occurring between speciea T&r1eties, Corkill 1950 {56). A conbinatiou then of conditions conduoiTe to eptillu:a crowth, aad herbage plants having a oomparativeq high growth rate ad. vegetative 4eTelopment should provide a mioro-enviromum.t havillg herbage deasit., favourable to optilrml intake b7 ·the grazing animal., This point is best illustrated by an extreme situation referred to b7 Du Toit et al. 1940 (57) under free rage conditions ia Seuth Africa. These workers cite Pole-lh'ans 1936 (122) describing 4-sert regions where pasture plants are widel:- spaced in bare soil g under such conditioas of , low puture den.sity animals mq starTe., but will survive i:a areu haTi:ag a unifora sward even though exceaaivel.J de:f'ioient in. essential mueral aad nutrient requirements. U.der i:atensive paature ooaditions Johnstone-Wallace 1944 {58) has .,. .LO - indicated that vu-iationa in denei v and height ot a pasture probabl,l" influence the quantUatiTe level of herbage intake in nursing beet cowsec1ea of differeat 'Dutu.rea& and aa rala.t:iTl!!I -nAla.ta'hili.t.,r • 18 ... ohangN ei·~h•r within or between putu.Na. as the result of chang•e in hei-bage a•v•lopment. Numerous factors influence palatabilit3 and theae present extreme difficult.¥ for stud¥ with precision and accurac7 1:D. the cue of in situ pasture. itaple4an (62) oonaidera the onl.7 s&f• eriterion for pasture palat ... bili'tw ie the proportion ot the amcnmt eaten to tha.t actuall.7 offering., In this respect he et&tff that it .is almost impossible to cet accurate eTiden.oe b7 a:tJ¥ method of aaim:pling. Nevertheleu, attemp·ts ha"lfalatable to free grazing s·toek. The relatiTe palatabili t, of the miscellaneous speoies was approximatel.Y the eame over diff e:ren t t¥Pes of land. Grasses showed variation chietl.7 due \o 11tap. and VP• of growth and the preaenos of bw:11. These fiud­ ingB being generall¥ 1n aooord. with those of othe1r workers. Beaumont et al. 1933 (66). D&Tiea 1925 (67) Stapledon and Jones 1927 {68), Stapledon and Milton 1932 (69), Sheeley' 1932 (70). L~t•r ·work by Milton 1934 (71). using \he same me\ho4 arrived at & 1nv•a'U.g&\ion of the relative pala\abilitJ of a1mpl• seed.a mixtures in with single species plois under sheep grazing. Ii w&1 found - 19 - that of the grasaea, Tillotlv' toned the baaie of the moat palatable m1xture1 ai though it wu not the hardeet grazed species among the pure plots. !here was an indication that gra~ing was incr•u•~ in unif'ormi t¥ among contrasting mia:tures in proportion to the addition of apecies to their CODJPOsitioni 9.h~.p on the mixture plots selec~•d mixtures as such rather than i.ndi~idual speciea from mixture,. Bed and 1hite clo•er were found to be 'more highl.¥ palatable than the grasses, red olover being the most h1ghl7 palatable. S1Dt1lar eoncluaions were aniTed at b7 'Davies (67) concerning the relativel7 hieh palatabilit7 of red and white oloTera. 'l'his worker states that on• reason w1J¥ clover maintains a much more uniform palatabilit7 than tb,e grusea is p.robabl7 that und8r more or lHa constant grazing the,­ never produce much st~JJUD¥ gll'Owth. but oontinue all the time to produce a relative abW1da:o.Ce of fresh and succulat lea.Tes. Oocka,ne 1920 (123) fOUD.d that the pal.a\ab1lit, of White ~loTer 1n ••• Zealand varies- with the seaaon, most beihg eaten b7 sheep in September. Danes (67) concluded "1;&t the ch1~ faoton influencing palatabiliv would •••ll to be ~e relative 1ucculeney of the herbage offered 1>¥ azq par\1cular apeci•s at arq- particular til\le, this bemg largel~ due to the at~ of growth of the plante. Shaw and M1lnGD 1942 (72) recog111se the importance of palatabil1t, in paeture crops u contributing to maximum food intake fo:r high producing con, bttt th97 admit that the etf ect palatable food hu on the lnel of food conauption ia not known. Thea• workers uaed the time 11pent gr.-ing b7 da117 001r• to u1eH the comparative palatabi11t¥ of green cereal pastures. Ml¥ t~d con were uaect, kept fr&m pa.eta.re and stall fed during the gruing trial. as it wu aas'1211-4 their behaviour would then better refleo\ the tfue palatabili¥ of each plot. ·• following resul ta wer• obtained:-- ffitHft GJ:azipg Time QJtr 6 4Mt • ~- i of Time. Balbo B¥• Pasture 45 52 Common BJ'• Pasture 21 24 '!'urlte7 Wheat Pae ture 15 18 Beno llarle1 Paeture 5 6 The four plots were laid dom in the same fi•• acre field; all plot, ••r• stated to be ideal for grazing a•eraging 4--6 inches in height with - - good s tanda. Al.though Bal.bo qe was the longeat this fac'\or 1r• :aot considered the meaelll"e of pal.atabilit7, a.a barle7 ranked second in height and appeared the most uniformly goocl pasture. It should be noted th.at ·the data were procursd over 6 d.qs onq, and can on.17 reter to compa.r&tive pal.atabilit¥ a·I; a particular growth stage of the paatu.r•, which are subjeot to wid.e va,iation in that re1pect arising from envu-onmental 1Dflwmcea. lurther U is an open q,1es·tion aa to how tar the tis• spent grazing b7 an animal on a particular plot reflect, the palatabili to}' of the herbage, without some indioa.tion of the cospu-a.tiTe grazing aotivit,-, whiah in:!luaic•e the proportion of the food ee.ten to that oftering.(61). Bon• 111l••i:,leat th"• '110rkera sU8geet a compa.rativel1 hi&h,er palatalailUT for :Balbo Jqe '\o ihat of Reno lSarlq. lfateon et al. 1933 (73) sug~e1. ,hat palatable foods will increase '\he dr;, matter intake of sheep from the eetillat•d optim:wn aTerage f1gnre of 2.5 pounds to 3 pound• per 100 pounds live wei,;ht. toodm.llJ>. et &1.1937 (74) ~oueider \hat azq attelllJ)ts to measure the so called normal appeti,te of sheep at different live-weigh'\e are eseenti&l.17 ai-bitr&r7 having nc absolute s1gn1fioauoe. The,y state that the ~ppetite of arq giTeD individual on a constant diet me,;y var,- ver7 w14•1¥ fnm dq to IJ.a¥• Ohanpa in nature of diet, 11 bal,.anoe" ot ration, pal.a.'tabili\7 and clipetibili ty, and the propor·Uon of coarse er euoculent fodde:i- in a ration mq cause abrupt c~s in the appetite of the individual~ It would 'be expected then that chazi.gea of tilat nata.re enterinc into the aeaaoJlal prod.uotion ot herbage would influence '\he lev•l of qua:D.titatiTe intake b;y the grui.Dg anim&l. foodaan et al. (74) demon1trat.ed that changes from a diet ot chaffed lucerne hq to one of the sae _.,. 1n a long oo:ndUion oocuioned a depression of sheep .. ih• average depre1•ion ot 0.42 pound, of dz7 aatter per dq amounting to 11.,4 p•r cent of the mean da.11,- dq ut,•r consumpt.ion., lmpro,r•d h&\r qual1-t, (fed ,m.ohatfe4) in all caeea led to 1.uc.reaeed. oonauaption. J'uriher work b;>r toodaaa et al«l937 (75) $mplicatae increased pa1ata'b1,lit7 values in striking increases in the foo4 oon.s,mption of 1heep when chanced from t,Jpical. lllnglish winter fodder rations to spring crazing. Thq present the following data;---- - 21 • ~ - ( \14.QA\ll:l 1934) Mean dail1 OoneU1aption en Graae Mean dail;v Consumption. ~ & 111 QI W.W W$ Sheep lio: 19-17 1-20 1. 4.66 5.06 146 3e36 125 2. 4.66 5.17 137 3.23 120 a. 4.99 4.92 166 3.70 157 9. 6.23 6.13 201 4.39 181 D1geaiion 81.7'£ 80.~ co•ff icien·~ of organic matter of grua. The !ood 0oneump\ion of gu:uig sheep was calculated on the 'basis of the digestion coefficient of the organic matter in. the herbage. 'lh.ae workers etate:-- 11 The obserTed increase 1n appe\i\e could not be &ttribu,ed to the stimulating 1nfluenoe of beillg 1Jl the open air after a period. of indoor confinement, sino• the sheep had bee kept in pen.a on the same field throughout the entire duration of ·the win\er feeding trials .. Heither could it haTe been. induced b7 the tonic effect of pusi».g euddenl7 from winter feeding to gruing, for the eheep had beooae well acouatomed to the grass having b•en grazing the plo\s for more than 3 weeks l>efore the ac,ua1111easureent of appetite was 'begun. It mus'\ be aacz:1bed in the writer's opinion to the high pal.atabilit;y of the ioung apring herbage. The result, support the contention that :t-.rm .!11:limala 1n general tel14 to over eai when first put out to grass in epring ••. , w lt was furlh.er found that a depreased dJ7 matter intake ot sheep at pasture followed. upon a marked ill.creu• 1:n ateamineu of pa1ture-herbage and red\10t1on 1n paetve qualit¥ u the season advanced. Th• influooe of thHe factors u the¥ lowered. herbage palatabilit.J were implicated 1D. depreaeing h•~ba«e in,ake. '?here ia eviden.ce :from Percival 1950 (76) 1n Bew Zeala:ad that seasonal ... 22 ... changer, 1n pasture mq influence the dailJ dry ma.tter intake of grazing animals. Three methods of measuruient compared. showed a progressive increase in dr.y matter intake between August and December corresponding with the seasonal inc re as ee in qu.a11. tt v and qual 1 ti of' pas tu.re 111 ( See FIG: 2 PAGB 300 ~ ~ ~ auuaption that an inoreaaing dr;f matter in'\ake of grazing an.~ale on the same ·pasture 11 rela\ed to an inoreaae 1n herbage pala,abil1t1' needs to take into acooun.t th• work o:f' Smuts et al,. 1940 ( 77) 1n South Africa. 'fheee workere demonstrated that the average dail¥ weight ot sheep inoreaaea or d•creaees according to the protein content of -the pas tu.re and th• season of the i•ar• The dry m&tter emretion 1n faecea voided appeued to beu no relat- 1onah1p to growth and •eaaonal fluc,_uations 1n the protein con:ten'\ of pasture ; in fact the lowes'\ Taluee were attained when the grasing wu pre,umabl.y most palatable. These findillgs being 1n oontradistinotion to thoee in dai;q cows demonstrated 'b1" PerciTal ('76),. Furtherbg their ,1nveatigations Smuts et &1.. calculated the dr1' matter consumption of sheep, from the daily dry matter of the faec•s and the digestibility of the dr.y matter,. On this Qaai■ the7 claim a stroM'relationshij betw•en 4q mat. ter cone"QIRJ)tion and U,Te weight of animals ., a. decrease in weight r••ul ting in a decrease in dl7 matter oonaumption. Using lleibere 1932 (18) equation tor rela~illg d:q matter oonsump~ion to boq weipt thef foimd that whU• "h• average dail.7 d:q matter oonaump­ tion v~i•s wi\h th9 saason of the 7eaz, an~ oonaequentl1 wtih ~ protein contat of the pasture. it is extremal.¥ constant when •xpi-••••4 per tmit of weight per¾ power function of the ••icht or square m•tre of bod¥ surfacee In the light of this finding thef sta1e:--11 The capaoitJ x·or dz7 matter co»eump'\ion then would appear related u 111 the same manner as the basal. m•tabolism, to the surface area or¾ power function of the wei&ht. ~is woul.4 mean iha\ th.er• 1a :a.o ju.tif1oat1on to a1u11lme that ahe-_p eat propor­ tiona\el;y mere per unit of weicb,t of '\he summer graz in,; than of the winter grazing. In fact, it appear, as if the weight of \be auu&l is th• do:miu&Ullg f&e~l' ud :cot the cond.i'\ion of the gruing. 1 1rom '\his statement it would follow that the lesding capaoi'q of a «ruing a11.illal 1■ regulated. b¥ the ¾ power funot1on of boq weight. . .It, as accor41hg to th• •~•rbient quoted , the :a:utritive value of the pasture - 23 ... DRl!"D~i.A ute111ia•s wv•o;.u.u, as 'l"W~'ill~,Pa Gr -~,&~l- s• 4r'J, "'"' ,r. T ... ,"" OlEiBl!r'WlfDlU same ,.._..... "'"''""'""""' ,ralue --.. ·•·- wo'Gl d ~';V-,Ul>!IIIMllllll•¥ 4r'J, ma,~~-·~ u~~£•-- ~A•~~~•~ft ~ftffl-~; of iutriuaicall.7 •1u11,u.i.,v::1 as "9µ'•"'•-- , as iaOJ'eased palatab111t7. ihil!I p-.it.•'ll•"'·i.•A would be related where pala:tabilit,- iu this Qase is \iiuit:1;.u.•1st:1• as the a1um4v4 of appeal hold.iag aail\lals to saiH pastve postulated. v1n that pasture is most palatable its earlT stages of develapaat '71iiiUlt!IR is f (71), (75). ~asiaed. is con.cuiie4 hu'bage palata- b1lit3 as aa 11aP11u!!11 '1"1111,11•~ l'l•t!.111fa111,w plaat allillal 89 tar aa ,1t in.flu.ace crwmti11at1Ye nAir:-0111U\T'll!I ca1ur11m:u1u. lfhat there mq :ao for uaai:ag sheep and cattle eat proportion.atel.7 aore we11h,t u q1~1n mature ta ao sip.ificace th8 nJt•nffilN Ul.!:>T,,•IP _ _,.._,._ .lflRJl"'liJl!lunll palata- ( 75L <11>. +all,1.l.J.U411,1f!IRII. as IIHlll''l'i>'fl'idli1H• palata'iUi V and n•r'IH!LC- li fl u gru••• cleTer sheep U.p.m c«.ta t of 'the large var1at1e:a 1111s ... """,.. .. - iu , - ars1u a.ctec1ra. renl ts a u.w1u,11,. • 24 • ot i•Yestigators ( 77), ( 75}, ud would. aooouat for the seasonal deprHaion ill herba«• coneUllptin in cattle and 1heep (76), (77), {75), aesociated with the uoreaaing ligno - eelluloee peroatac• Bukett 1948 (80), Patton 1943 {82), (58),aa4 d.epreaaion in protein (77), (80), iu punre herbace as it ad:vuoes ·tnar4a ma.writ~. It would aot be UJU'eaaoaable to expect that an iuoreastag :fibre con.teat of pastve with a caaequeat lewere4 digestibilit1 value wnld depress appetite ancl. herbqe iJl'\ake ta gasbc aaiaals wb.Cl the effects •f 11.ature herbace •• rummut digestio• are •xamiAe~. lel'au and. Juller 1942 (81), haTe indicated that the pr:9aace of lipu u the cell wall ot plants mark:ed.1¥ a:f'feota the availab1lit¥ of celluloae for di&eatie. The 1ip1f1oat1•• process b herbage plants is oae e! matur­ atien, associated alao with a reductioa ill protea con.teat and water soluble co•■tituata. lh'a allowug for this reduction ill available nutrients, 1:t 18 fwad that the oellulese ot material coatauing a low paro•tage of lignin, is more read.ii¥ decomposed b;y rwnen digestive pr•o•■•e• thu. ,he oelluloae of mature herbac• with a high peroentace of lipin. LO'Un et al. 1948. That hi«h].7 li&11ified plant material requires a longer t1:ae for cellulose cligeetion ill the rumen of aheep hu bea ahown bT Hotlund et al. 1948 (84). Th••• workus caclwled from u Titre ad 1n vi,ro studies 'that the rate of oellul••• dic•••ion was markedl1 1nflunoed ~ the diet. The appetite for either lucerae or gru, ha, being direct!¥ affected. b¥ the rate of cellulose 4igested. Of particular interest iD. thia work was the fact that on a basic diet of poor qualit7 grass hq both cellulose diceation (83). and. appetite were stimulated bj' emall aaounte of .-agar, but markedl7 clepreeeed b¥ exoeaeive amount■ • More au.gar beug tolerated if protein. was &ls• given; optiaal cellulose dicestion neoeaeitatiDc a balance betweea readily available carbob¥drate and protein.. In conJ,D.otio~ with iueaiigatioas of the efteot of diet en rumtaal cu formatiu. in. 4aiq cows O.cle~ and Kleiber (53), attempt•d to deiermiJle if palatabllit¥ -varied iD. different fields of luceme. b in.fluac• of maturit¥ on palatabilit7 was a further objective. 'Whilst no conclusive results were obtaiaed, thee• workers iD.dicatad that alfalfa 1n.creue4 ill palatabilit7 with maturitT. The occm.rru.ce of bloat ill the animals used depr•Hed herbage con■"QllPtion so making a true estimate of pal.&'\abilit1 _,., .... ,wible. writer 1uln1t1 extat which rumual clis·te:nsion - - :f'ollewb.g llllli:Hil..t./111,(:IC is likel,y ....... ,'11',,.v.~-..LUIJ.!~,~~~- ... .L anYnd"'"'"·'"'"'"'' and P"Ull>ll' nm,.,.. (58) ..,,.~ with advanoed na:~D~­ is na:i:-o~un11 low b. lip.h, ..... ,,... .. ,..,... in cell.action 11~1:f'i•d m,11;u:,ar:J.111U.' selective ... -,-.. ,AM; 1n cattle., Tribe 1949 (85), makes a wi'ih a1.1."''•"'· ,u 11¥ , or • will to mer•l.Y m•i1.uu11a reuo11.1:1, 1ological an.d ps;va1lo.1.ogJ.cuu u alwqe potentiall,1 "'"'""'?..,,..,. in palatab111 v, whilst is none l~•s b a}.. It is certain foods differ in pala:tabilit7 b),. and lower palatabiliV limits doubtlees exist, re1pectivel7 or re:fu.sal food Ill c),. are bdicatios certaill pastures hatlag differat cons ti tue:a t spec iea are pref erred to o the.rs Dder free ,rJ1t1:l,'ft1 and preference is mwrA•,~ b7 a greater consumption preferred d).. an .Lr Jl.e as th•¥ m9¥ relate to herbage coneumption b1" the animal under conditions cond:u.ciTe to bloat. Our knowledge 11 eeriouaJ.¥ liilited in respect of the precise pasture con• ditiona under which bloat beoomea manifest. and it will remain so until detailed field studies are aT&ilable. The aasooiation of pastu.re quantitT and t1P• with bloat can be con- aidered th•retore onq from a circumstantial upeot. That they mq be oontributori faolora ia borne out b7 the often reported aeuonal inciclence of bloat (24), (13), (16), (19), ita uaooia\ion with lUBh paature herbage (45). (46), (41), (42), (35) and with herbage VP• conducive to optillUm herbage oonaumptioJl Jaoobsen. 1'epe, and Cannon 1942 (89). The quantitative level of herbage available is implicated 1n the etiology of bloat bi' Viljoena 1922 {90), who BU€!4t•i• that ·the condition a.riaea from too rapid aza.d too large a coneumption of lucerne or kaffir corn. lllepe et al.1946 (91), impl1 tb&t the 1y'pe of herbage oon•med ia not of auch import as the r&te of ingestion, coupled wiih quantit7 of herbage consumed, whilet Scales 1946 (92). states that bloat in oa\tle is oaw,ed ~ eating too much ioo :fut. Detailed obaerT&iions made bj" the writer, illuatrated graphioal'-7 1n the following section, indicate that the time to onset of bloat in da1Z7 cattle 1s mcr~ed. u the quantit7 of herbqe aT&ilable becOllles 1•••• Similarly. the writer has controlled both the onaet of bloat and it1 degree of eeverit)' ·una..r paatiu-e conditions oonchloiTe to optimum intake 1n dai17 cattle, bi int•rm1ttent pasturing throughoui th• dq. thereb7 restricting the quantiil' of' herbage available for cc::meumpt10D. at 8lfl one tiae. The pasture condition■ preTailiJI« were conducive to the onset of bloat iJl cowa ehortl.¥ after pasturing where f'ree grasing was permitted. It will be noted 1:a FIG:10 ~ 21 and 1:a l'lG:13 9¥ 22 in the following section that where grasing on a pasture conducive to bloat was $('4,!'(/l restricted within a certain time limit r bloat did not occur in the {fU-e-'1 'f1FfST example and waa r•dnc~d 1:a the hcond.7 example. It would not be -an-reason• able to assume that• reduction 1n th• quantitative lnel of herbage intake was effected, relatiTe to those other grazi:ng periods 1n which bloat occurred. is bloat WU av-.a..a.-.i. eaee1 obaervatioas were •er• WU ... 28. J.A..r.u.g d:l.ftereaces a;rea writer Zeal&l.d cattle were ~••tri~t•d a11 P--• ,..,_, . ...,.,"" &.r81' mu,,·aJ~Sal\19 l)Ut"1'°8a 1119Ul.4 •·•ill11tu&u1.u.u su:tfioe area W&b s~ilai-4'" ~J,:u,ted approx1Blatel1 WU ,gr &!IHH:L area. ....._.'''""'··'·" h1uff'iaieat grass cewa soil level withh were l!T-■a 1u lllallUlE~i' ., pe;riodic decr.e8' of bloat ; no bleat wu raaorCUla. l:lttrl.DR' iJ1 pl._ goup a a pae'h.Z'e e&J"lier top-clreaee4 :aitrocea a:a4 ha,rhg ~• followiag . . -- Species 9 6 l ------------------------·-- wa.a recor&e& ill all cows -~- !the are& grazed wu composed of the following species:---- _, _________________________________ _ Perennial. lqegrasa 0ockef'oot Goosegrass Prau-ie Grass Poa .Azm.ua White cloTer 11 33 l 5 l 49 Theae cODdUiona of restriote4 pasturing wve oonduo1.,.. to rapid ~st1on. b;y the cowa on reoeivin& the new break of paature, thia behaviour u aeuured by bitea per ain.ute, being particularly apparent in the low plan.a group. .Aa rapid ingeatioa 1a so widel.1 reported u be1Jlg the charact• erittic behaviour aaaociated n,h the onee\ of bloat, (8), (14), (15), (16), (42), (45), (46),(90), (92), (120), (121), it would aeem that paatur• quantit.1 wu the lim1Ung facto,r 1D. the cues cited. pQ>centace of graa• epeo1•• in the first example quoted is of j.ntere,t in Tiew of bloa, 1D.o14eno• being g911,eralq aaeoo1at•d with legume 4am1nan.t p .. wr••• Bloat hu been previoual7 reported 1D. ••• Zealand in cattle grazilag paeturee whioh were mainl.¥ qegrus 1D. 0011posit1on, and atimulated to aotiTe growth b1 nitrogenous manuring 11'.qlor 1940 (93). The reduction in quanti1yr of herba.ge available for con.at1111ption ie the prill&r¥ difference from tree grasing which underlies the s1■tem of rationed grazing, recommended as a measure for reducing the incidence of bloat, but u 1et to be proTed. (19), (38). lf the quan ti v of pa1ture available per unit of area grazed ahould be an etiological !actor in bloat. then a high 1D.ci4enoe would be expected during the seasonal grand period of herbage growth. Tqlor (93) 1n :Rew Zealand reports that the September-October period is probabll the moat anxious time in the 7ear for bloat incidence in the :Bq of Plent7 region. In the ,um• oountr;y Johnaon 1950 (94), indicates that the first outbreak: of bloat in the l'a:t.ranga area occurs with the spring !lush ot fl:'UB during mid- An.gust and continues througn September, October, ( • I• 40 /fJ ----e_._ OCT wb,nr:Q'I( ....... - - "" SD n ( ;rMl)h 'l. Hy~r• and -30.A.- - ,h nllf' Fig.I. Note production peaks Sept/Oct.period. After Lynch (95). Intake Measurements (Figure 3) . "'( ?i= 0 i ');-- 0) 12 ...J t: A 6 Cr ~ ALIG )' f-' T l .,., ·••.. ... ... ~ , ·, ·-.-·-·- C 'N .. ,A· . ·- ., r ; . ,· A ,,... . ... ' .- ....... ., , .. . .. ' ,---... ·-... ~--. \ -. \ \ \ 1V LJLC JAN n:B MAR APR MAY l·1i,:uri• :: ,Ji,rn,. tilt' i11tul-. 1• uf dr., 11 111 1t1•r i11 po111uls p1•r 1•o w p1•r 1lu~ Fig.2. After Percival(76). as 'n'l:U:l.111!1'.ll" .. it ei,her aud in are 41.anaa ioa. ._ "'\U • a d.a•astra~e that in EBD.ar&l a September, leH f•llO\'JU.& covs• pasture VP•• 1. Oppoaue. pDJllll<>atllla are MIIIW.clllu.1 fiJU.\taf:a as in~ake lo,-aber ( 76) • available .... at pasture (J'IG: 2). in. so far: ~=~•m,n species, is deaastrated a hei-bage UlilliliJV!!IL..., grewih, palata.1>1• apeaiaa, so woui., DD ""-& .. 3. D grasiug would. be -i;a1.a~ spevA.-. IUilTUC a gu1a111ILl."fll,1i ad .11,1e,PB1e !Alllllhl>M••_. pas tvea UllfS.~&l!J.i,_,. i - &OCeJ".-liag .XlaTiea (67), ad coatin.ue a ._, • .,, ... vv ~1aa,1.-,,~• aa4 ... ,l'!!ftlk~, 111,n leaves per grasd,DC m:ea, lenl .u-•···-- in.take, ill 11•aessar:il1' seaa i-ri'eatiag D.lll."l'UMftl aaal e • a.o will criticise nare&ll'R 1n.~&11B meu11reallllll te1MU11Qtue • as au111a:a~ should ·nun•• will little a.eed for fa1lve to aolm.owleage .un.ter e»;:,umm aon.4:1. tioe .-111W1tn herltage &Tail.able w~1 depa.4 oa. the v,egetaU.,re contained 1peaies. !luat ia most ofta reported u aocurrin.g un.der / condit.ioas - 31 - of vegetative herbage production and consumption. c) Where the qu.antiv of herbage available for ooD.auzption bu been. re4ucecl. b¥ RlanagelleD.t facto.re euch as paatur• rationing, or restricted. grazing time, there haTe b•m ouea ot a recluc\io:o. in bloat 1noidence and severity. 4) There ia evidence that seasonal peaka exist for the production of herbace, which vu, wi\h the vege\atiTe growth of the apeci•• components of a putura. e) The ••aeonal incidence of bloa'\ 1n lfew Zealand is reported u being highest during th-. aontha ot petk pasture production. Coincident ' same "'"''"""'''-" To thie s·tage pasture has been coneidered in ao far u ita T&rious chai-acteriat1ce are l~ei, to be illportant inter-aoting factors with the l'or thia reason an eDmi:nation hu been aa4e ot puture herbage dena iv. coupled with length, 1 te palatabili t,', and the tn,e 11114 quantit,' of paawre available. In the mioro-en.Tiroueni erlatent between harba.ge plant■ ad the g:rutng animal, the moat impor~ant a1ngl.• consequcoe ot these 1n\eract1oJl8 1a raeolTed iJ:Lto the amount ot herbace remOTe4 an.d consuaecl b¥ the ania&l in a giTen paeturiag time. »..iunoe of abaolu1e aignif:t.can.oe is not available to perait a oonclua1•• statement that either of th& aforementioned puiure oon41:Uone4 interactio:a• inhibit o:r st.imul.ate a particular quantitative level of herbage intake. linertheleas such eTidence preaented is convincing int~ 1mpreea1on that where optunm cond.itione of herbage palatabilU~ and. qu•zrtiv obtain, compatible with the ful.17 efficient mechanical act of inpation,then opt111wa herbaae in\ak:e in the normal gruing u.1mal w1ll 1101t likely re1ult. Jlext, gu formation in the rumen of the gruing animal is a nonaal. biocheaioal reaction coneequ.ent upon the microbial disintegration of the herbage oonaumed. Quin 1943 {96). Accord.ingl.7 then, under the same puture oondJ.tione.those interactions oonditioned b,J the paatui-e which inhibit or atimulate the optia'wl leTel of herbace consumed would be •21>•01ed to 1n.direotl¥ inhibit or atimw.ate - 32 - both ·the optimum rate and volume of ga produced in the rumen of the normal graiing animal. In ·this connection i't should be borne in mind tha·t there is strong evidence to indicate that the quantitative leTe1 of food conaliaed in sheep Quin (96). and ca~tl• Cole et al. (51), 'faehburn and Brodie, (52), 11 propor"ionat•l.¥ r•lated to t.he rate and volume of gu produced. in .the rumen o:t the normal etall-1'ed animal"' Oole et &1. (51) have deaon■trated that a higher quan·ntative leTel of feeling re■ulte in.& greater rate and voluse ot rumen gaa product.ion than a lower ln-el of feeding. Such being the cue an increasing eructation ot gaa would be neceiaea17 to prnent the building up of gu preaaure in the rumen. It would be exp•cted that the on•et of bloat woJlld be con■eque:nt u:pon a failure of eruota:hon to oop• with gaa :formation. Should herbage fro• dif:f' erct puturee var,- in 1 ta gu producing potoe7. then it would be expected. that diff er•nt rates .and 'Yc>lues of nmtm gas would be prod:uced iu a given time. !ollowi:ag the coaaump\ion of ~• same amount, of herbage. That thee• oondi'\ions ma,- preT&il ie 1ndioate4. ~ • 1 ~um~• t ' with th• full7 e!fioieat mechanical act of illge■tlon. & W'-lt&6UU/IJIR rumen gaa nr,r:nu:uJ t On such paetw•■ • 33 - The time in whioh rUlllen gaa production would reach ib peak would depend on eith•r the ra,e or duration ot herbage ingeation,in 10 tar as th••• factore dete.rmine ·th• quantiq of herbage 1n\ai:e under tb condit1o:n.a aesume4. wo\lld oonoeiTabl7 re1ult in the oneet of bloat. The rumen gas preasure woul4 determin.• the aeTeriv of the condiUon (25), (115), Yhich woul4 T8ZI from aligh\ to aevere bloat, depending on how far the qtl&ll\it7 of herbage conaued approaohod the opti:anDl le't'el • . .An examination will follow of the extent to which iho•• 1».teraction11 conditioned b7 the grazing animal will b• likel.J to contribute to aaa.te bloat. ~ • • i ... i .,. !1 !I r, ~ I ~ !1 ~ • i I : :I .. .... .... a 0 ,... • gi .. ... 0 1 ... • • 8 • .,. ¥ t • ~ t: J I ,... I ~ .p ... .p ,D • • ~ .. I 1d 1d • rs e I I ~ I k k • • to 0 0 k k fl) ii 0 : m ~ .a ,3 • 0 0 J .... [ Ill • .. ,D d ... 35◊- oaua •• 111 are T&riations 1n the inge1tioa act arising troa -•-111\1, ,i;l.'NH,a,g muusige:■fln, impo&ed, partioalarl.¥ u tho,e ,,a;ria:tia.11 infl11euoe quaatita·Uye lnel of h•r~ace intake. 'lhe implioationa quaatit7 in oon- trilmting r6'e and. "0.1.1111111:1 nuaa. gu prod.uc1i1e. b.&T8 prniOW11l7 intimated.. 4 farther f aotor .u.1111,11111¥ now cons14ere4 is the qwllitative lffel pu"1re reuon n.a:ru,11...a additic, 4oaina:uce in a pai;tve nnnii:.an ....... , ... u. .. ~-u~,, • ..,,. 9Peoie1 Ya.:PY~lfi . .D' in carbohydrate !his qual1tat1Te factor a:riaing interaction ii .... ,,,....u.s.111111 im1,or1a11,ce. ehon late:r, irUnmlates !heretore those amblal gaJ,-.:>u ... ,,. ... UVlli!.U.Jl,lij4iUA11JU the will w.~,-~,,u. following aamner:---- &I rmainant 8s influence on putva.cian,01 MtY1116:ftltM4 V''141M+,W;K :P!:P:te! ♦YY:M: :1:Mi A+ f!:Nt ..-,e,MYffm!t& 4M'ft!:¥ ~~• A'li out1et it will a.a teehniloat .. ,vill considered a- d) ~•·~S(>na~. a.a example 6 h expressed 121 , or graz- f ir~1 t and s t h carried out of 1 pasturing th&y spent 7 to 7i ho~1rs grazing. only du.r mg dqlight frcm 6 a.m. onwards., Atkeson et al. 1942 (104) used a limited number of dairT cows QAd made their obaervationa only (tu.ring the 12 da;ylight hours. ·that milking oows on good pastures grazed for a shorter time th&11 cows on poor or madium pastures; cir¥ cows and heifers grazed for 7 hours. Jobnston,t-Wallacs et Ql. (58) observed 1n dota.il 4 nursing cows of a beef breed on four 24 hour periode and concluded that the3 grazed on an average for approxima.tely 71 hours. Seath and M.iller 1946 (106) investigated the influenae of t-.mpsrature on the grazing habits of di~ cows and conoluded that hot waather {85 - 86° "I maximUlll) lowered the grazing time bi one hour ooinpared with cool weather (72° 1f maximum). Such conditions also altered the ratio of d& ,r.raz~ f;rom ia:pproximatel,- l during the cool d~s to ap:proxinatel,1 nigh~ grasing 1 • 31 • a;o4 Wallu• ... ".,_,, nal!!,aw·-.-,,,.. 6 s•·h IIHlthlJ 1n:lie:r,,-ala, lu(aa-tsia •••• "''"'~-- ea aa "'·"'""_.F.,. aat -••••,a►• -~- WU B.PINlt, 1'!,11, ◄-•11&1!>11 Cl' 7 :h.t111i2'11l in ua.-.·.11..u ... of 11&1Jtaoc:J.1; 1950 (60), aon .naatl.J atatiea that gifln a treu •••- daiq cows _ ..... ,., it io.ec,•ainuey 10 aa 8,Vllil'&fl[a tor a her, eUe :l.niJ.YitGa\ aimala Nacb. 12 JLH.Hu,-x per Al!!U.HIVag; (108) t ( •""-.iMA ..... _ grazing time 1'1111 rHll~l-An'I •t~W-.if 1101"9 \etwea a.m. ~.,,.,,. ... .,, f'a:lrJ.¥ constant imder all weather _,u..i. tt;r1~u1.g wu aUQued u & ml.l1u1,e uich or men w•r• aad. dJl\ta wu •btained 1u 1ix ••ta of twma over &'D1>ro:;Q11,a1111J.J1 .,. thl¥ 1n1ien&l.a. &T.Uabl• t1-• wu divide.A 4'1,' and night perioda, 85 per cat ot \e\al ,r.,:.a.z:uil& wu BP'Pli m 4'1,'light and. 15 per cat 48.:rk.a••·· wu cows were conditione4 te atop guing 1100a at'tll" c.\a:rJmeas tel1111 !hi■ habit wu lu:oka, wha the hou■ of da.Y• light 'beo•• 10 11hor1 oowa 1a.tiaf7 their -p , e;pet1tu «u..l."A.E,. pe:rio4, an.d. th.Retore e:d;a,4114 their afternoon ,r.,:.uing ,\ b.,-ond nightf all111 BauooGk (60.\, conolu4e4 putu• conditions 1naa.c. loD.gll" ,:ruing and l"W.liDating times 1n con than oontUtiona are optiBal for quaat1t; and qUillit,' of herbac-61 con m-• gra1ing good. putue 1u the ••• dq / :ra.1J$.• aeragea on a q'Wlm.titatlvel-7 poor pastu• the :ratif beco.-1 7!H 25. 1U'll weather ( t,aperature F OTC") cauae4 d.iaoomf'ort to the OOWI ad WU cona14erea. __ , ..... a break a:f'ternoon li!Ell.lolii;l,IMil: periola atud.iea tor ga,aing ac1s1vit,' ■1u1ill!r0 are Ter, limUecl. !ribe (85) ceaa;l.411"~4 beha.Ti,ur of one aheep wu representative of a ,r.,:.oup. a teri•i Of hour o1nsenat10U O'f'll" & 7ec it WU fmmd that 1818 ii.Ile 1n aumer wu 1:pent in gruing 1D 7.00 -- 19.00 hour period ~ 'lil.W~'"""•il!, 'fin.1-, 1tO,itb.1a lor the 19.00,-7.00 hour period the • . • . . r N :I - m a .. ! • Ill 1.11 0 r ~ i (I) .a J N 0 I l .... if .... 0 .s .... " 'li;t • t: .:1 l;J (D CD Qi • J a .... .-.... 'd i 0 i j .. • k • i = i 0 .. i .... lfll 0 i ti .... rd i • rd (M ! ~ s 0 : i " it • ~ r f • I !t t ~ ~ r f '· • r ·, Fig. 3. -39.A.- 1•11 I JS7•11 I JS7 l 8·11·46 l ~ l Ill I r•-~m~;r'77r.] ~ IIU,,,l ,,,,,,J ~ ~ 7~·3 l 1118 m ... ....i 0-12-46 - ill=] j 1H47 I h L i ~ j:J , s-2-41 -~---~~J-20·2·47 ---i, 4i6-l 11 ."'JI·; 110·4·47 ~-J I - 18·5·47 -29·6·47 7911 I JS79Nl 3S7 Distribution of Dairy cow grazing behaviour. Grazing (black),loafing(white),lying(diagonal lines). Note cyclic nature of grazing and longest periods after a.m. and p.m. milkin&• Cows were dry during the period 29/6/47. After Hancock(I09). - "t"II - on a rela\1Tel7 '"•6"•" OD1Ullll .... ·-· 1■ •••ura i'a 88.SUIIII: M'8:t"l!Ut84 4 •;L;DY.1i.ll OTer , ..... ----·- 'f"'.l'"a1i"llllll!ruia 1u11'lwaan. tor 11' were •• • D&rul.VJ.nUr ~~IT.!~-r~, on a.epencaa 011 m A 111 •-·■ .w.a: beef Cffl wer• - 111»:u.\e -M•·•• were r•••tMI. OYer l.&'I :LOll9 OCC'l:lr & ,1,;V4JI.VWIIIIU. Baacoek (108) bi.tea •. ~ -40.A.- ~; .. .... . ; ]Or----------------------. 50 I ,o 30 1 • • • • '-• • 7 . 8·- · 9 10 II 12 I 2 5 6 1 8 9 10 II 12 I 2 3 4 Fig.4. Shows the distribution of the rate at which dairy cows graze(bites per minute).Note that the rate was highest immediately after the morning and evening milking.i.e.?a.m. and 5p.m. respectively. After Hancock(I09). .. ~ ~ i\ r 8 r 0 ► • I .... - f" !i ' fl ' f .... ,, i 0 = 0 I: r a ..., ► I 0 & I E r • I .. ~ J,l • I • • fl ' i I ;. 0 i I it .,, • r I I I .. t-1 ' I fl ' " ! • "4 ,,., ' 0 I I It • 8 • • • - • I - - grazilt.g aot1T11ij, o! eaoh oow was aeuured 'IQ' the :nU111ber of bitea per half aiJlw.te at 6 minut• b.tervals over a ens hour peried. !he average number of bites per halt miJnlte recorted fer each cow durug the period was as i'ollowa g ..... T26 36 '54 34 17 T25 34 The grazing aotivit7 of cow T72. although stead¥, appeared to be less thu. the other cows in the group, marked eeleot1Te prefereD.ce beiag sb.01111 for the lenger herbage. JD. examiD.ation of' the cow's zcntth a.t the ead of th• period revealed two deformed first iaoisers &md a severel.¥ absee1ae4 g\2111 the twb. to 'f72 was fond to be similarl¥ ieformecl. !here nuld be eveq reuo:a to believe that mder quu.titati"fel,J poor pasture oond1t1o:aia the erasing effioien07 of 'f72 m tei·•• •f herbace consup\ioa wwld be seriousl.¥ impaired, al theugh to outward app•a.ro.oea the grazing activiv did. aot appear abaormal. Al'Ul•U&h tile probabil1t¥ that Tariation.1 in grazing d.uratio• ad. rate influenoe total intake lnels is cenerall¥ acknowledged, there is ao sup~rting exper1~eatal. evidence. '!he prebabili't7 is 1trencthene4 h&wever 'I>¥· the :f'indhp of Schalk and Jmadon (61), with stall te4 fistulated cattle. !beee work•rs remoTed food beli at the cardia as thq were projected into the stOIRacll, and weight• were recorded. It was reported that a rapid ingestion rate resulted ill a greater weight of food enterug the rwnen in a given ti.me thaa. with a slow ingestion rate. After a 24-hour fast one cow was evid.911oe4 as ingesti:ag 30 boli of luo•m• in the first 5 millut•e, and 19 boli in the auccee4ing 5 miw.tes of feeding. !he rate of ingestion was depreased b;v increasing 11u1tiet7 0 ltllpalatable food, aaci aa increaae in. rwnsn TOlU111e; the latter factor ala• reduced the ti.me period of illgeation. Te epitomiee then, the grasing actiTitJT of ruminants as aa uiaal• conditioned ill.teraction which &8¥ infiuaae the level of fee4 oonaumptio•. a) Iamuamt gra111ng et-cldiea ceD.tribute to a fuller 11Jl4ereta41nc of in situ. u.illal-pasture 1nteract1oaa, of which gramiJlg activ:l:t,1 is the prb&r7 b.teractioa condi tiolled l,7 the animal. b) !here is ,;e:rteral acreema t that 6½ - 7i houre dail,1 b the &verac• 4arat1on of grasing activit,- of free grazing oai.tle. Individual. aillal u.i herd T&riatioa occurs. ... ... !her• is T.'ll"r,ffD' w.u.i,u.u. indicates u u ·th• depend.a · indi vi4:ul.1 v, is !here is evidence that :la primaril¥ a diurnal aet1T1V eattle. e} v-,:a.m.ui,g aetiirit¥ fons a i:;rclic pattern throuchout a 24 hour 48¥ \Jiu -Yw,.&.a•t,1.c.1a rate hu 'bea eonr in 4&117 cattle uu~nmcm"G a 11:.4••.a.mil.l' 48¥. lU.fferenoes 1n a11.111it,: rate (bites / ) ocov ,iH1!1'1l:!lll'a1111n inii:viclual cou pasture. h) rate of in claiq cattle is eTid.eaced. as ... ~ .• .,. higb.eat • at oei1:1ni11uit1: a gr1u1:ag 0701•• 1) claiq oon is av14eace that rate at oe1:m11111,g eycle1 following mil.king. J) There ia no a.lnaolute .&.u.•u.v• rate ingeation in :n:m1ma.,1s at pu'tare mnuence 1 .... 1 k:) There .v1,a.cn20e aiall cattle that period. ingeation Tarie1 the ·nigb.t dif:f er•t :rood.I. Jl\u:ther,. a rate low rate of reaul ts intake greater lesaer weights respeotiTel,1 the ••• f ooa. • The enent to which seleotiTe .m111,·u.llk11■ en:ter into gruing aetb·:l.t7 is necesaaril7 a con.Jectural upeot of l"\U'liDan.t beh&Tiov at pasture. lt ie none the 1 .. s ou which 18 iJlp~t~t. u 11 _,. readil7 be o•oe1ve4 thai. v~iations OQO'IIJ' '•1••• fm4 ~1;w.:~;1 species lD.. ~• 4e&re• of aeleoU.vit¥ an.cl pref e,enc• f o;r pl.;tla aelect•4 whi~ Taria,iona would be ez_peoted to in,iuenqe. 'both the. &'Dd. q'UJlliV o:f her'baige intake. According to. Stapleclo:,i 1948 th• sheep 1a m.ore refined in it11 111V a-1.tQi ""~~n•; sheep 1eleoi1 ind1~1d.lull pla.ta p41,tchea of pasture boTine 1aeleot• in pa.tohea. •suing illt•• ot ) Pftf Kancock (108) auggeata that 1.;he cow ·- a:aell l•bs m aelectio:a eur:pl••• fed. 1D oon.clu4e4 t - - a speo$41a. 6"•-"""""'6 area. .1.u1im11e of the sense of smell l•)s deprived. of the •••• of illft'll.lfll- lobe,. It WU found th&\ 1d:um d.Ufereat or mii;\'urea speed.ea were t•t noZ'IUll ad •••ll•Wicient .... &. TAJl":I.A._ aaell •• film•~••• no differenoe ~-t•-•·- mitiaJ. u ~~BB 2 old a 1ialtl,W'& herbace aaapl• WU oharacted.a~ia _ .. ,-... ,... l.t wu to•~ plats a vn1uur a plat wu con- l\81.'D&mt ,ei.ecnu.on ■1M11111m ( 85) ansa..1;:a.011ea. in Ji.-···· bf grua eat & creatw ftilUll'l"illllA ftT.i!l,A'!!"III is Q.91llJl•lll.8J."IIA A:IID.CJDCIC ( 60) 'llo 001',ribu.te low ,O:,Ulla,r .1,V.l,W,U/IJJI .. 111::nn .. ,r J.D'IEII per ia OT'llU!:L'ft.111' ( / aiD:) oeet11:t 'between ••'• ot twme amt 'b) the tiM value 11 a characteristic specific to set tWiD.li'J.ii latter piece of entenee 11 ope question u it 11 proba)le u differenoes 1n digestion ca case 41f:f'erencea Ulli◄"""•"',Nl~ £Jra1:m1: time val us even twin a eta h&T• oon.aued ot ,1muar q'WID.ti'1" aud quali"7. !h.18 worker diafflllaea fOllleqv.enoea of 1eleots.ve g;rui:ng mcJ. oon1id.a:ra ih&t uate:r ~i~l p-~• oc,nlitiu.a ihe uaaleoii1Te grue:r will o'b•a.m a full food. a J.Olllitltr • )II\ a PllQhologioal O'U~~g UU, llD4 :---- COWi were uGvQ••~g u~uwa oowa cowa 111eoeea. wer, A'5J.Y8 AEIIZ-0&1?9 aore au.4 aeTer 0011ena·u.on ... - .. 9.l"l,;UIIUA ., ... ,.",,. .. u.. oa a bloat t - oue 1G1l&1UIG. 88 a ·-· ... a more rao.m.a. : "' a qualtt- oav.a;,.ag -•- white clover • 0QW9 lll'PillllJRill,fl oa .. - 45 - cows between gr&sse1 cloTers at the ~•x1m• stage of putva growth uauall.7 aaac:u,at•d with the spring in .-u1~;;i.•i:4...,"' ~oimm1on (94). report■ 4&117 cows break-fed pas~• oon.ducive bloat :never at ·Um• R"t'J1111t1rn. o1over preferen.oe to gaae. In con1.rut Cola et al (25). attribute a red:110111011 in bloat incidence . .,Sll,o.ei!lc.v of cattle select co1u1iderable Amr,nn,1:1111 of a coar1H sem1;i.J1,f!:.J.Y ,mpalatabls weed ( Pol;rgo:a.um avicu1are !1rat grazing en am;m.a.,!Ulli lucerne. inoi4.enoe followed a re4uct10A weed indication wu of the oow1 8 jp"1111,z;ii.na: ae:tivit,r or extGt to which luoeme was consumed. during the grazing period • . In the abaence of specific work dealing with the selectiTe habits of grazing X'Ulllinct1, writer submits the following tetat1Te augpst- ioas assuming such habii1 eJd.1t. a) Seleot:l:re gra1ing habits 1n so f,a u in!luei:u:se quantit7 and quali t.1 of harba«e intake will proba'bl.7 be subll,1eot to w14e variation depending on pasture conditions .. b) !he un.eelecU.ve grazer would be e:q,ected obtain a full herbage intake in. a shorter Ua• tbm the seleoU.ve o) 'l'b.• degree of seleotion enroiaed will conditioned bi" animal :mm111i1e••m pra.ctioea., Where re111tr1ct or d.ela.y grazing11 seleotiTe behaviour wo,lld pro'luibl¥ 1nhi'b1te4,. d) Bloat is most often associated with rapid :l:ageetion or unseleot- 1Te gruing a.ctiTi'tl'. e) Under paature md manage11ent oon,U.tion1 conduoiye to bloat it would not be imprpbable for the time onset to bloat to be ahorteat for the un.,111eotiT11 gruer, accentu:t;ed where oo:ad.Uiiona in. o) obtain. 91-..... ...------------~~..............,~ uitez- ~,u .. u~ is u rwauauts -••~--••~•~•J cer,ain is a 41reot outcome of a certain quat1tat1Te intake of that ..... ,r:-., .. ,_ oonduo1Te to bloat. both are ... .,, ... u 4etermi:ne the same in (61), it is :aeoessa;cy &:mmin.e rate ;ii;",4·,sl!l.i.U¢:; as "'"'"''""''"'""' beha:riov • J'iO • d$tUJ1ini.ag ret•r• .... ee-.ug M V,JNJIIUJ.J~ on.set uf ......... on deer••• oase 1a - in area aeTe.re111 iliet.arm 9 llroar1U!DlN •i•w of in ' ' Ti8\t&l 11 wt1i 11 ~•1:r0•c1t1cm . an.4 o:n• eow 18'0:.l"cl.ecl • aairk•db 6 a aano••l•r a oa:anula m.11■1~11111,0 •111•• Hg. ti WU .BH'IIFll!lr' & ;&"Wll.ull&L J)l'iltlHntt'• u aT•rMe o:iazJ.D« 2 wu reeord.ecl in •J.Jll'1i11F'O~U a:re fir11t OCQ &11 aows. mi.us ••c••••11¥ iauoate the WU COW U40&~-~ -~•• : oco• soae did. 7 .r,utu.·a ao•• miioatioa till• (6) refers oaaet of 11eTffe hffd. l hov 001111eno:m11: a 'l!'lla111~1 .... perPAi&l qegrua ••1.,,41wu; oloTR. ... 47 ... »a.the (24) cites the cue a daii;r heri :restricted to l hoar of grazing a 1uutve ooaaeiTe bloat, which bloat occurred w1 thin the hour; the operation of a sillilar baa bee obaerYed .... ha Zeal.ant herd. ( -'i;lpadix ) 113 ~ t"MNlril:111 Olll.7 milt'U.t11M1 Of C,l'UUl£ OJ1 8 100. White P••iiure as daiq 001'8 UutW.U. P•J.'lldltte4 ma.ic-RJ.n m one oue ill which er••• and eve m this time bloat occurred.. an11u1r,we1ro report• {Jo) out of heifer• blown., two die4 Gil cookstoot and SlOO white sward.111 a half an 7 d.ai:r,y anillal.1 m approxillateq ii ..... ,... Halli, 1945 (116). al. (15) Allarica, that fee41:D.~ grab l hO'IU' 'before paaturb.g lucen.e induced bloa1i ta • aTcage of l hour 6 mm,. for 9 cow• OTer 2 48.,a, as aeapared. tom time 011.sat to bloat flt J ,an,.,.... 12 owr the preoe4mg 11 dili'a Aurmg which bloat occurred ta ••• ocwa, wi '11.out supp1emata:cy teed on the ••• putve. ltva:na 1948 (117) !lll.titi.£:IIM'l!!,1'111111"1 pr04\\C8 bloat h 3 (2 1 uu •• v- '1Ull"T1D.A!' for 12 a lil'~tUaULU OloTer paatve,. all stopped stood liatlessl.7 a whil• before searchb.g for rough herbage mich thq g;r&le4. c...,a.oeaeat pub.g) was •n••-'&£1 rapidl..f t BZ.UiliWIIIIQ no & ..,..,UrJLDIEII of 1112.n:u:&IIIIB (i.,e111 1 attar ,,... u1i1.1.~•u• ••lft~r.u distress qmptGJU, heifers wer• 4UOOllfOrto ai.•w pr,etHtG::t..:a,: ilacua1ic on 1eleotiTe gr&aing U 1a inter- th.at t.ailcate ,liDv.ea. jg.-,-.. ..uK s11lectin3.T ,lra.t thn• ci-uing,. obsener1 report the onset of bloat in daii;y cattle within & rar•l.J' bloat all.al.fa putur•• Oole al. (51 4epaatvmg (118),. Oole ia,•r 00-wori:e:?11,(cited b7 Oo1e et al.,(9) ) 1 d.a'lia en rnoT&l. con trom I bloa1d'a.rmg gas foraatic I I - - & 1'1lmMIIIJ. l!'IA .. AI' 1'88 .... cow .receiYed pO'GIU\s A':raan alfalt&. 8 W&II ,,.:.,r•n alfalfa a.m. ha.A aouuaed ., •• '31 au4 a.m. lea41Dc rumen ueeJ41m11 part1a+l¥ pl,,..4 ad. at •••• 00\I' ... UJ.llllli>ifll!N -.d UD.COIIU-0 (96) \\IT4-u.11&u• ot iuoreue4 intra,.,rwaiNd :,reasve Pr111Hunu:•• waa 1u dair,-.oow 1faa of ILtter a aeal .1.uc,11r11.11. which 11m1-.aro'I 11a1re.r·altbn,ll!'11 attar c,m:in•:v;r1;a.o1• lucema, ( Alll'll'HIMa 1D.11ak•CII • 49 "". Col• al111 (9) dzaw lll,liT.-1&:UiilD re1..-1on be11weon n-•~,-- con usocia:ied m ••• 8, &6V-.U. 81'9 atwlifl ABVWa in writer bloaii. ' diaperaed ad n,merou report■ u1001ate rapid ,ra11inAI" .u.i.u.a.u.-uw 18 OJ.J.•WDil? & ca.re 11ll'Y87 OOCWB -..""ai:w. 18 .UUD.ICE'.ll (14) re1:1:01m1ew1.1 A.l••P.s.u11. llll.DP"I/ IIIAJi.aa.!i,lll .. --e:i access luc•m• J,-11.14,R~ •••• ad CCWII more that bloat 1:a fat laabs on lu.cene was av1:,,1,1i.-•u. ravenous more allow1Jur: a 8 naoept1b:ll1V of lac11atmg aa co.roa:irea ar• !!111RCIIID'l1 as ~ caw• 1in1.1.u.ua u are aore cows. to gre&ier 01 ..... of are l'8Por1;e4 m cattl•• (87). 1• or ia ·-· &l\"9 '.l'llltY'Wl!IPiUul O.m.dv {)2). 'lhia grazing asaooiat•• - • I I J .. I I i .. .. - •aliAV& ■•GJ:UU:la.a■ 0& ,. .. ,,. -.;~11111 ..... ~nraaa aiu-uur ran1a .,.., •• ,fl • ~,mtk1111r 11"8.t•• op.1.1u.oa u --.,.,... 4UJ:'J.1Ml! 8Ga8 WW,ir,lll;;~Q:'11 m,naran 'I .. 11 .. ■DD- ~-•~•A d:f'9:fml8.1Jm i■ bp11oate4 " 11111■~11!1( - ot ooa41\laa Mu!ar1111m1 hi• olb.ioal ODIHn'all.0118 ooue1un or a~wu~wia• l'DB IID'l'IIUll!llll■ 00 i.mnft2>t.a1uu1 $l uo~4 ■.ft'lt'.l'll"'l oo alco b• 1\ID&GJI y U' '1\1&11..1 a .. bloat r111,raaa1l11 .. ,n,.,.,,,,,.,, J.'\1lla $l r1•• .... WBZ!.GB AAflU,9.1' -· •ce'U" - •- '11111.a•tl.,;i,..6_ .. 1 0 :a I I 1 ~ I I h 0 -:; 0 ~ Ji I J 1 I • • I • • 0 j I k - I • ... I t :i ii' 0 • I \4 -d +it • 0 BLOAT -+• SLIGHT BLOAT ♦ FLUX :PULL 0 FLANX LEVEL WI!H RIB - 1 FLANK BELOW RIB LEVEL BAT! OF CRAZING ON FIRST PAS'l'Vf!IffG AFTER MILKI!iQ. DAY No: a.11 . p . m. 17 PRE-FED HAY ANO GRAIN ---- -- - 18 -ll--X - 20 - - ----------- I O"I 0 • ► • ... 60 - liP1'• 9. P .. uture. :lo~ l. J~111 ..... -... ,.....,.,,,,,_ beh.&viow.- generalll wu sh.om tu her4. m·ul:"in,.• fir1t 2 wem ci-uin,; Puture 1. On being r•l•as•d fr•• aA--~~ con wd4 gallop towar4s pt• ad on 111».tutn,; um•c:U,a1slll,f 00111ece acrH.Te lym if some •• •»◄-e. actiTelJ m a -•'"'-""'"'"'"& the 111uae b•l1ari.our ;wu evident • soon u a moTe wu aau to open the pa4d.ook l t app•a:r•ll nr111:u~a:i11.011 W&I for pu ta.re. Dq hTAber. 17 111 a.a. ObJect. acti.iri117 •:f fae41ng 9 lb11 l11CH'Jl8 K li'b prior tc "Dlll!lllll.lll:11':J:.:ll.li!'~ Oow releue4 :froa •Uld.ng 7 a,m. Pu ived... CODS t:'IWCSG~9 biting m.a:rz11a. bloat., iumtn. Moyeaata., fer• stroncl.¥ eviden.t betwee slight ad IUUited bloat. Depuiived. 9,.15 a.a. D..,- liuaber. 18. P••• ObJect., Putvecl. Gramuc. !o inve,·Uca,1'1• nawe of p-amin& actiTit, witlum.t 1uppl•enta:t7 f••41:n& prior 'tio puturing. 6,. 45 P••• imeUa.tell af \er llilll:ing. llat• vu ezcesaiv•. brok:a cml.7 DJ' oecuicmal short walJdag, a4. 11.1':l.'Dlt;~ Bo-~-~--~ wu select llructatum.,. .i.v,..,a-"'-" recoru4 a1'!tia1le8 ci-uing.,. 11:mle:a slight u.d aan:94 bleat. Depastured. 7.43 p.m. TOl1U1ta:r11,. an.a • i • 61 • . 1'bJ,c1. •••• bloat 'nadtit•· unr._.,riote Pae'NJ', lkb.ir.• oted , ---c-. it teil t1.-¥ ,~· tea a.ftv oas n.~at'l~•~ 'tw 8i8cul. tat1on.. were no1q. et#>Jic, and ' frtquen.t 28 rnmutu att•:r ir&zbg commerioe •»••4ie l'\Dla .,. •• u : a.,eo,.a. Ti'tulJ.¥ 30 ~~t•• attv the on••• of alight bloat 4v iJ.oat eonattiv.f• Depae~. 1.12.p.m. ~tw o-ui:Ag had TOltintarU7 o• .. -"• Diacu,slou. 1, will ,9,ed. ihd ' th•· itborteat time m,et •lf.&lit ))lo•t 1111-..t.. ••iac .r•w • J.1 • npp1--IU'¥'. p.-rtor 1' !he 1bor,e,-t ,u. ·a••• to. IIIAl'k4tel , u.d. , ••Tve 'bloa, oocnvrecl •., ~ .• •. 1 . . cm: 1>at 101 18 ••• ot cru1ac. inc raw na hlgl'lfft ~ the _ttrat 20 a1mltea • of bloat oceti.r'i••cl J>a, lo: 2Q wha the c1Uat1o• ot cr•11lc •• l t. ae•,r• 61atre1a •~Pto••• hlgb ~iratia ra-.. croa.wc, i'e nt.cteat. .It 'ie :to \;e noted '1lat oubc eont~4--.... • . when atronc 4~\~aioa -. w14at. • llmtD IIOff .. ,, 'ftN la ~ -•tll after the OILlet ot blM\e .. ··- .. .. - • • • • • • • • • • • • • • • • • • . 1-lj ..... ~ . . H 0 • IIIS/ 'lIIII OlfSlf '?O ILOAT +++t·~o-~...!1~0-~...!2~0~_ 23:;..o __ ~•,=.0 __ 2;,o!._~--=60::..-~---1;.10!._....----~eo!._.----'1'1r--,---"1'Foo"--------------- - - j ttt- - I I I I I ---' ~ J_ _' ~l _ - i _ '_ I g:0~f!.r r:If~~r"~~n _ TltlAJCU Of JDSIT COW Z. ~,=.;--- - '/ ♦Ht SEVDII BLOAT Ht IIARJED !LOAT ♦ + SLil:HT .BLOAT ♦ 1LUX PULI. • O PLANX LIViL WITH RI• -1 PLANK B£LOW RD LEVEL ~ ++ 1111 +-1111 Qt = C ~ cc PA6T\/RI lfo: 1 JAlfUARY 1950 . " 1 / \ \ \ // \ \ \/ \ RA'TE OP GRAZINC ON \ FIRST PASTURING APTER \ MILICIPIG . \ t DAY llo: \ u.ll. p~~•»IPA5Ttl1'lD AKD PRiUMU PROM GRAZIJIG 1 ---- --· - 24 25 0 10 20 30 40 6o 70 80 90 100 GRAZING Till!l,Nl~UTES. I O'I I\) • ti> • f • .. faj ...,. Ot? . . H H • ~ p, o' f-J ~ c+ . . Ml1'S/ ~ q +++ ~ t, ++ tl ♦ er;. <:> ra. 0 A -1 = ~ i .... • C - f C. Pi i" -~ i 40 -... c c,:: 0 3 !'a, 0 l!GPIU Of BLOA'J' ,OD S1A'l'B ., ++ --...._ OP YL.UK Ill L.iPT l.UNM!t ~ ~ TRlAlfGLE 01 JERSIJ COW X. ,.) --- .. • + .___ .,_ I .___ "" I ·+-++♦ SEVERE 11LOA'1 -._ "' / +t+- lORJrED .8LO,\T ---._ ,,, / •• SLIGln' :BLOAT --.._ _ _/ ,, ♦ FLUI rULL 0 ~=---:iii::::!!!!::::=::::::::::::::::~=======~----~~ .. ::::----~=~=~=~;~~=---------0~-~·ELA~N~X~t~E~Y~BL~W~J~T~H:R~I~B~--- - - -=---. -.::::. ,. -1 7L""X B'ELOW RH LEVEL 2 IC - - - - - --- - .__ , •l 700-- 5 lC i 60 0 Po "" i-,... z ::: ~00-­ z ... . ,.,. C: ;,: ;;; ... 3 0 0 0 ;.: t­ c c:i:: 200 lO 20 30 '° 50 GRAZTJG T]lfE.NlNUTES. ?ASTURi Wo: } 'JAIi/ FEB 19~ • RAT ~ OP GRAZING Olf YIRST PASTUR!lfG APTER MI LK11fG. l)j\J llo : a . m. p. m. J AN: 24 f'E8; GRAZ1"G CYCLI '!foe 1 ->'--lC 2 - PftE - PED 1 7l b. CUT GREEJII I.UCllltJIJ: ' ·- - - ·-- --•, 7C 8o '\ ' ' ' ·-- -- --- I 0\ \J1 • a..m. . - in Ultll:UIWIII: .... ... 00'ml•Jl0•4 a\ a..m. flank b•inc below ri~. WU ~?nk•• b7 walkiDg and ••leo\1•• Occurred. fer• regular repeat. »._, 18. 1. 38 a.•. uaetateq Ste&4¥ ref;\tlar, 07cle. "' GratiAC• 0eue4 9.29 flank b•in« sl1&hU7 blon. Cow I roained l U l'(Hle ... -at ..... 11.2 001111eD.oe ~'U'~~•Wii•• lzj 1-1· ~ • H I\) • ~ p., t-.i f-'· ~ p., 0 c:+ f-'• < 1-1· c:+ ' "" '" < p:; OF FLAl'fJ( IN LEFT Ll/NllAR TRIA~GLE OF JERSEY COW X. ++++ SEVERE BLOAT ~♦+ MARXEP BLOAT ++ SLIGHT BLOAT + FLANK FULL 0 FLANX- LETEL WITH RIB -I FLAIJJr BELOW RIB 11:VEL ---=--:::--:::::--==-=- - -·- ---------- - -- -- - - ___ ,.. __ .__. ___ ...,_,.