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Item Reproductive consequences of genetic improvement in clean fleece production in ultrafine Merino ewes : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science, Massey University, Palmerston North, New Zealand(Massey University, 2023) Ramos, ZullyTo date, genetic improvement of Uruguayan Merino sheep has focused on selection for reduced fibre diameter (FD) and increased clean fleece weight (CFW) and live weight (LW). The effects of selection for these traits on ewe productive and reproductive performance have not been studied in Uruguay. The aim of this thesis was to evaluate the impact of a long-term selection program applied in an Uruguayan Merino flock between 1999 and 2018. Phenotypic responses of yearling lambs and adult ewes across 20 years of selection demonstrated that selection strategies applied in the flock resulted in heavier animals that produced heavier and finer fleeces. These phenotypic responses were accompanied by a decrease in body condition score (BCS) at mating, with a small positive change in ewe reproductive performance. Strong positive genetic correlations were found between yearling and adult expressions of FD, CFW, and LW. The genetic relationships between FD and reproduction traits were negligible. There were generally favorable genetic correlations between LW and reproduction traits. The genetic relationships between adult CFW and ewe reproductive performance were unfavorable. Genetic trends indicated that the breeding strategies applied during the study period were effective in improving genetic merit in the traits under selection (FD, CFW, and LW) and caused only marginal genetic changes in BCS at mating and ewe reproductive performance. A total of 13, 22, 42, 22, 24 and 29 genomic regions were significantly associated with FD, CFW, LW at mating, BCS at mating, pregnancy rate, and lambing potential, respectively. The results obtained in this thesis will be used to refine the breeding programmes for Merino sheep in Uruguay in the future.Item Studies of the flock mating performance of Booroola merino crossbred ram lambs, and the foot "conditions" in Booroola merino crossbreds and Perendale sheep grazed on hill country : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Animal Science at Massey University(Massey University, 1983) Alwan, Mohammed TahaTwo studies using the Booroola Merino crossbred animals were conducted. In the first, the flock mating performance of Booroola Merino-Romney crossbred ram lambs mated to Perendale ewes was examined. The second study comprised observations on the incidence of foot "conditions" in young Booroola Merino crossbreds and Perendale sheep grazed on hill country. MATING PERFORMANCE Eighteen Booroola Merino x Romney ram lam's (6 control, 12 mating group) were selected according to weaning weight, fleece characteristics and general body condition. Nine ram lambs were exposed to ewes prior to mating for two weeks (trained) and nine kept separate from any ewes (untrained). The ram lambs of the mating group (6 trained, 6 untrained) were allocated to six groups of ewes which were "single-sire" mated. Groups 1, 2, 3, 4 comprised 140 ewes each and Groups 5 and 6 comprised 100 e'\.;res each. The ram lambs were changed after eight, eight, seven and seven days of mating, Periods P1, P2, P3 and P4 respectively, and a total of 12 "single-sire" mating groups generated. All ram lambs produced a satisfactory semen sample before joining with the flocks. Mating commenced on 30 March 1981. The flock mating performance of each ram lamb was assessed by recording the percentage of ewes raddled, percentage of ewes returning to service, percentage of pregnant ewes, percentage of ewes lambing, docking rate and weaning rate. Differences among each of these parameters were attributed to various factors. Trained and untrained ram lambs were similar in most of the observed parameters of flock mating performance. There were no differences between individual ram lambs within each sire-group (trained or untrained) in mating performance. There were differences in the percentage of ewes raddled between first and second oestrous cycle of mating. Live weights of the ram lambs were measured from weaning (December 1980) until the end of the trial (December 1981), at weekly intervals during the mating periods and at monthly intervals during the post-mating and post-shearing periods. There was little loss in the mean live weight of the mating group ram lambs after P1. Overall the live weights of both groups increased consistently throughout the trial. Semen samples (collected by electro-ejaculation) from the ram lambs of the mating group were microscopically examined for general motility after each mating period at least for three days. Recovery from mating exhaustion occurred four and six days after P1 and Pz respectively, while three and two days were required after P3 and P4 respectively. Semen samples were also collected on two occasions from the rams (only 15) as two-tooths and examined for general motility, sperm concentration and percentage of live sperm. There were no differences in semen characteristics between rams of the mated and control groups. The two-tooth rams were also subjected individually and randomly on three occasions to pen-libido tests, each with two oestrous ewes. Mating ability was assessed by recording the number of mounts attempted on the oestrous ewes, the number of services, the reaction time to mount (in seconds) and the reaction time to service. There were no differences between the mating and control groups in the number of mounts and number of services performed on each occasion of the libido test. Significant differences were found between both groups in reaction time to mount and in reaction time to service but only at the first libido test. It was concluded that the Booroola Merino x Romney ram lambs had achieved satisfactory levels of flock mating performance under the conditions of the trial. No adverse effects of mating on the post-mating body development of the ram lamb could be detected. Semen quality from the ram lambs deteriorated during mating but recovered shortly after mating. The use of ram lambs as sires had no adverse effects on their semen characteristics and libido performance at the two-tooth age. FOOT "CONDITIONS" The incidence of abnormal foot shape, foot scald and footrot was observed in Perendale and Booroola Merino crossbreds. The animals were generated in 1980 and 1981. Observations on foot "conditions" were made at the lamb, hogget and two-tooth ages for animals born in 1980, and at the lamb and hogget ages for those born in 1981. A scoring system was used to rank the various foot "conditions" (shape; scald; footrot) which were assessed separately. Booroola Merino crossbreds showed significantly a higher incidence of abnormal foot shape, foot scald and footrot than did Perendale sheep. Significant differences in foot "conditions" were also found between (Booroola x Romney) x Perendale and Booroola x Romney sheep. Sires of the progeny generated in 1980 and 1981 provided a major source for the variation in the incidence of these foot "conditions". Estimates of heritability of each of the observed foot "conditions" were calculated at different ages (lamb, hogget and two-tooth). Sex of the lamb caused significant effects on the incidence of abnormal foot shape and foot scald between ram lambs and ewe lambs, but not on the incidence of footrot. Differences in the incidence of abnormal foot shape and foot scald occurred between 1980- and 1981-born sheep. These differences were attributed partly to the particular climatic conditions in each year (notably the annual rainfall). It was concluded that under environmental conditions similar to that of the present trial, long-term selection programmes could be applied to enhance the natural resistance of sheep against foot diseases.Item Shearing Merino ewes at different stages of pregnancy : some consequences for the progeny : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science majoring in Agricultural Science at Massey University, Palmerston North, New Zealand(Massey University, 2008) van Reenen, Erica HelenMerinos are bred primarily for wool production, valued specifically for the fine-wool they produce. Wool returns have been diminishing over recent years so using management to improve wool quantity and quality is beneficial to growers. Shearing ewes at different stages of pregnancy has been shown to potentially influence the follicle population which in turn could achieve a finer, heavier fleece in the offspring, although this has not been examined in Merinos. A consequence of the diminishing wool returns is a greater emphasis on meat production, resulting in a shift in focus to increase live weight and body condition in order to increase reproductive performance and produce heavy lambs for sale. The whole Merino wool market is also currently threatened by the perception of overseas purchasers towards the practice of mulesing. Mulesing is undertaken in approximately half of New Zealand's Merino lambs as a means of reducing blowfly strike. There are few data available under New Zealand conditions for these pre-mentioned management factors that influence Merino production. Therefore, the aim of this thesis was to profile the live weight and body condition of single- and twin-bearing Merino ewes; investigate the effect of shearing time of Merino ewes on the live weight, fleece characteristics and the follicle population in their progeny; and to investigate the effect of mulesing Merino lambs on their live weight, dag score and fleece characteristics. Two hundred and ninety nine Merino owes were bred to 4 mature Merino rams on day 0 of the experiment (d0; May 20, 2006). Pregnant ewes were then allocated to one of three shearing times; mid-pregnancy (d106), late-pregnancy (d141) and post-lambing (d191). Ewes were weighed and condition scored on dO, d79, d106, d141, d191 and d283 of the experiment. The ewes produced 128 ewe-lambs which were used for subsequent measurements. Ewe-lambs were identified using DNA parentage testing to their dam's maternal shearing treatment. Ewe-lambs were weighed on d191 (approximately 6 weeks of age) and weighed and dag scored on d191 (approximately 6 weeks of age). d283 (approximately 4 months of age), d359 (approximately 7 months of age) and d499 (approximately 1 year of age). Ewe-lambs were wrinkle scored on d191. On d191, 60 ewe-lambs were mulesed; the remaining 67 were left un-mulesed. A skin biopsy was taken from the mid-side of the lamb at d359 and analysed for primary and secondary follicle density. Two mid-side wool samples were taken from the lambs; one at d359 (approximately 7 months of age) and one at d499 (approximately 1 year of age). The first of these samples was analysed for washing yield, colour and fibre diameter. The second mid-side was analysed for fleece class, staple length and staple strength respectively. At d499 fleece weight was measured before the mid-side sample was taken. Twin-bearing ewes were heavier (P<0.05) than single-bearing ewes from d0 (start of breeding) through to d79 (pregnancy diagnosis). They were also heavier (P<0.05) following this period. However, this is most likely due to the weight of their foetuses. Body condition score of twin-bearing ewes decreased following lambing until d191 (tailing) but recovered by d283 (weaning). Single-bearing ewes were more likely (P<0.05) to be rearing a lamb at d191. Single-born lambs were heavier (P<0.05) at d191 and d283, had heavier fleeces and had a higher primary follicle number index than their twin-born counterparts. Shearing time of Merino ewes had no effect on lamb live weight at any stage of the experiment. It also had no effect on ewe live weight apart from in late-pregnancy where the mid-pregnancy shorn ewes were heavier (P<0.05) than late-pregnancy shorn and post-lambing shorn ewes. Shearing ewes in mid-pregnancy had no effect on the fleece characteristics of their lambs. The progeny of lambs born to ewes shorn post-lambing had a significantly greater follicle density, secondary follicle density, follicle number index and secondary follicle number index than their mid- and late-pregnancy shorn counterparts. Mulesing Merino lambs had no effect on their growth, live weight or fleece characteristics. It resulted in a reduction in dags at d359 and d588 which is likely to reduce susceptibility to blowfly strike. The purpose of mulesing is to reduce wrinkles around the breech, and in this study, the more wrinkles a lamb had at d191 the greater the secondary to primary follicle ratio, total follicle density, secondary follicle density, secondary follicle number index, primary follicle number index, total follicle number index, and fleece weight. This suggests a productive advantage to sheep with more wrinkles; however, they also had more dags and therefore were at greater risk of blowfly strike than the less wrinkly lambs. In conclusion, shearing ewes post lambing increased the secondary follicle density of the ewe progeny but had no affect on fleece characteristics. In contrast to experiments with other breeds, shearing Merino ewes in mid-pregnancy compared with post-lambing had no effect on fleece or follicle characteristics. There is an opportunity for future work investigating the mechanisms behind the response of lambs to shearing their ewe post-lambing. The results suggest that maintaining high ewe live weight and body condition score throughout pregnancy will result in more lambs reared to at least tailing, and heavier lambs at weaning. Further work is required to examine the potential benefits of differential management of single and twin-bearing/rearing ewes. Mulesing lambs reduces dag score, and hence is likely to reduce flystrike rates but had no effect on live weight, or fleece characteristics. Alternatives to the practice of mulesing that give equal protection, compared to mulesing, against blowfly strike need to be found.Item A study of the inheritance of follicle and fleece characteristics in merinos, New Zealand romneys and their crossbred progeny : a thesis in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science at Massey University(Massey University, 1987) Meikle, Heather ElizabethA study was carried out to investigate the inheritance of follicle and fleece characteristics in Merinos, New Zealand Romneys and their crossbred progeny under North Island conditions. A total of 637 animals were sampled from the Ministry of Agriculture and Fisherie's flocks at Tokanui. It should be noted that the Romneys studied, were not the parents of the crossbred animals. Six flocks were sampled. Least squares means of the Romneys, Superfine Merinos, Local Merinos, Superfine Merino x Romneys, Local Merino x Romneys and Backcross (3/4 Superfine Merinos) were respectively as follows: secondary to primary follicle ratio (S/P), 6.68, 18.06, 18.66, 10.92, 10.32 and 15.81; follicle density n(P+S), 35.73, 69.69, 82.07, 49.57, 45.92 and 73.60; primary follicle density (nP), 4.72, 3.70, 4.23, 4.12, 4.23 and 4.40 and mean fibre diameter (MFD) 37.26, 20.71, 22.56, 26.24, 28.23 and 21.21. Of the fixed effects tested (age, birth/rearing rank and year of sampling) only age exerted a significant effect on most fleece and follicle characteristics. The repeatabilities for all follicle characteristics were greater than 0.4. Most objectively measured fleece characteristics also showed moderate levels of repeatability. Heritability estimates for follicle characteristics, calculated from small numbers ol daughter/dam pairs, were moderate to high. Phenotypic and genetic correlations for 21 fleece and 7 follicle parameters are reported on data corrected and uncorrected for fixed effects. An attempt was made to predict S/P using stepwise multiple regression techniques, but the resultant equations had low accuracy. There was negative heterosis in both crossbred genotypes for most follicle characteristics. LWT showed the highest level of positive heterosis. Methods of main gene detection were used to investigate the underlying genetic factors controlling follicle inheritance. Although follicle data had skewed distributions there was little evidence for genetic segregation for n(P+S). Multifactorial inheritance of n(P+S) was indicated. Two or more loci are possibly involved in the inheritance of S/P. The S/P genes appeared to behave in a recessive fashion. In contrast, the current results suggest the presence of a main gene for primary follicle density in both types of Merino x Romney flocks.Item A search for genetic factors influencing immune responses to a killed Mycobacterium avium subspecies paratuberculosis vaccine in Australian fine-wool merino sheep : thesis in fulfilment of the degree of Doctor of Philosophy in Animal Science, Institute of Veterinary, Animal and Biomedical Sciences, College of Sciences, Massey University(Massey University, 2007) Dukkipati, Venkata Sayoji RaoVSR Dukkipati (2007). A search for genetic factors influencing immune responses to Mycobacterium avium subspecies paratuberculosis. Doctoral thesis, Massey University, Palmerston North, New Zealand. A study was conducted to identify associations between genetic markers and immune responses in Australian fine-wool Merino sheep to a killed Mycobacterium avium subspecies paratuberculosis (Map) vaccine (GudairTM). Blood samples and immune response data (antibody and interferon gamma, IFN-gamma results) were obtained from 934 sheep from a longterm Map vaccination trial undertaken on three independent properties in New South Wales, Australia. Blood samples were genotyped for eight microsatellite markers that included four (DYMS1, OLADRW, OLADRB and SMHCC1) from the Ovar-Mhc region, two each from the SLC11A1 (OVINRA1 and OVINRA2) and IFN-gamma (o(IFN)gamma and OarKP6) gene regions. Vaccination with GudairTM induced strong antibody and IFN-gamma responses as early as two weeks post-vaccination. Between-property differences in magnitude and trend of immune responses, concomitant with season of vaccination and magnitude of natural infection prevalent in individual flocks, were evident. Immune responses in controls on all the three properties remained consistently low, except for slightly elevated IFN-gamma levels at a few time points in controls of properties 2 and 3, concomitant with exposure to natural infection. There were only 2 alleles and 3 genotypes for marker o(IFN)gamma but other loci exhibited extensive polymorphisms, the most occurring at OLADRW which had 42 alleles and 137 genotypes. Heterozygosities varied between 33% (OVINRA2) and 87% (SMHCC1), while polymorphic information contents ranged from 0.31 (o(IFN)gamma) to 0.88 (OLADRW). Genotypes at loci DYMS1, OLADRB, SMHCC1, OVINRA1 and o(IFN)gamma were in Hardy- Weinberg equilibrium (HWE), while those at OarKP6 were in HWE only when rare alleles (<1.0% frequency) were pooled with the closest size class. Departure from HWE, resulting from possible preferential amplification of alleles in heterozygotes, was evident at OLADRW and OVINRA2. Associations between immune responses and genetic polymorphisms at the marker loci were examined by analysing both genotypic and allelic affects. The study revealed several genotypes/alleles at different marker loci to be significantly associated with antibody and IFN-gamma responses to vaccination with GudairTM. However, the majority of those effects were inconsistent across the three properties. Based on significance and consistency in effects across the three properties, five genotypes (two at DYMS1 and one each at OLADRB, SMHCC1 and OVINRA1) and three alleles (one each at DYMS1, OLADRB and o(IFN)gamma) were considered either ‘probable’ or ‘most likely’ to be associated with low IFN-gamma responses, while a genotype at o(IFN)gamma was considered ‘most likely’ to influence high IFN-gamma responses. An allele at OarKP6 was considered ‘probable’ to be associated with low antibody responses to vaccination. Considering the significance of IFN-gamma responses in protection against Map, it is likely that the identified genotype/alleles influencing IFN-gamma responses to vaccination would also influence immune responses to natural Map infections. However, further studies need to be conducted to determine the role of these marker genotypes/alleles in protection against paratuberculosis under natural infection conditions. Key words: paratuberculosis, OJD, Johne’s disease, sheep, immune response, genetic markers, gene polymorphisms, MHC, SLC11A1, IFN-gamma