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    The effect of shearing ewes at mid-gestation on reproduction and performance : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Zoology at Massey University
    (Massey University, 2000) Hanna, Julie Elizabeth
    This study tested the hypothesis that shearing ewes in mid-gestation causes an increase in lamb birth weight. Growth rates of lambs were calculated to test for any additional trade-off between investment at gestation limiting investment at lactation. Liveweights and growth rates of lambs were analysed for a difference between the sexes with the expectation that sheep may put extra investment into male lambs, compared to female lambs. Experiments were conducted with mixed-sex twin pairs to determine if the male lamb was able to receive more milk than the female lamb. Sixty ewes were selected after synchronised mating and pregnancy diagnosis: 30 were twin-bearing and 30 were single-bearing. Half of each group (twin- and single-bearing) were shorn at mid-gestation (approximately 77 days before lambing) and observations of their behaviour and estimations of their food intake were made. Shorn ewes adjusted rapidly to shearing, exhibiting no apparent difference in behaviour one week after shearing. Shearing led to an increase in ewe weight and lamb birth weight. Rearing twins was costly for the twin-bearing ewes: they were lighter, had lower condition scores and less wool growth than ewes with singletons during late-gestation and lactation. Twin lambs were born lighter and grew slower than single lambs. There was no evidence of sex-biased investment in this study. A slight trade-off between gestation and lactation was apparent for shorn, single-bearing ewes. There was no difference between twin lambs born to shorn or full fleece dams. Shearing ewes at mid-gestation appears to be a useful tool for increasing the birth weight of lambs which could lead to an increase in survival of newborn lambs.
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    Maternal nutritional programming in the sheep : effects on post-natal growth, mammogenesis and lactation in adult-ewe offspring : a thesis submitted for the degree of Doctor of Philosophy in Animal Science at Massey University, Palmerston North, Aotearoa New Zealand
    (Massey University, 2014) Paten, Amy May
    Developmental programming is the concept that environmental factors, particularly during foetal life, can alter development, metabolism and physiology of an organism and this can have consequences later in life. There is growing interest in developmental programming in livestock species, particularly effects of maternal pregnancy nutrition, which is easy to manipulate. Recent research, using a sheep model, has shown that milk production in ewe offspring may be susceptible to maternal nutritional programming, such that over nutrition (ad libitum) of the pregnant dam, compared with maintenance nutrition, may impair their first lactation performance and result in the weaning of lighter lambs. The present study however revealed that maternal nutritional programming effects on lactation performance in ewe offspring did not persist over their productive lifetime. In a new study, the critical programming period was narrowed down to early gestation, coinciding with early mammogenesis in the foetus. In this study only twin-­‐born ewes were examined due to their economic significance in commercial sheep production and due to their increased susceptibility to nutritional insult in-­‐utero. It was revealed that, in addition to over nutrition (ad libitum), under-­‐nutrition (sub-­‐maintenance) of the dam during early pregnancy also impaired first lactation performance of twin-­‐born ewe offspring when compared with maintenance. Transcriptomics analysis using RNA-­‐seq identified that nutritional programming affects late pregnancy mammogenesis, rather than secretory cell function during lactation, in ewe offspring during their first parity. Ewes born to ad libitum-­‐fed dams, in particular, appeared to have impaired regulation of cell cycle while ewes born to sub-­‐maintenance-­‐fed dams had reduced expression of genes associated with the extracellular matrix, both of which may influence cell proliferation. As a consequence, both ewes born to ad libitum and sub-­‐maintenance-­‐fed dams may have had fewer mammary secretory cells, resulting in reduced lactation performance. The findings of this thesis indicate that differences in first-­‐lactation performance of ewe offspring, as a result of maternal nutritional programming, may be mediated by impaired proliferation of secretory epithelial cells. These findings contribute to our knowledge of the mechanisms of developmental programming of the mammary gland and presents a platform for future investigations which may ultimately lead to the ability to manage and manipulate lactation performance.
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    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 Taha
    Two 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.
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    Zearalenone in pasture and its effects on reproduction in ewes : a thesis presented in partial fulfilment for the degree of Master of Applied Science in Animal Science at Massey University
    (Massey University, 1997) Kramer, Richard
    Zearalenone is an oestrogenic mycotoxin which has the potential to cause reproductive disorders in sheep. Zearalenone-producing Fusarium species are present in New Zealand pasture and it is likely that the amount of zearalenone present during the mating period may be sufficient to cause reproductive dysfunction in the grazing sheep. This study consisted of three trials which aimed to measure zearalenone levels in the pasture and sheep, and determine the subsequent effects on reproductive performance. The first trial investigated the levels of zearalenone during April in various components of the ryegrass plant at various pasture sites, which included urine-patch, dung-patch and inter-excreta sites. Zearalenone taken up by the ryegrass plant was also determined. The second trial comprised of 6 groups of ewes (n=10), and compared levels of zearalenone and related metabolites in the blood and urine of ewes grazed on pasture or chicory and either orally (5 mg/ewe)or intravenously dosed (2 or 0.5 mg/ewe) daily with zearalenone. The subsequent effects on ovulation rate, conception rate, and number of lambs carried was also determined. The third trial comprised of 4 groups (n=110) of ewes, of which two groups were grazed on grass-dominant pasture and the remaining 2 groups were grazed on chicory for two weeks prior to mating at which time one of the groups on each grazing treatment was interchanged and the ram introduced. The levels of free and conjugated zearalenone in the blood and urine were determined and the subsequent effects on ovulation rate, conception rate and the number of lambs carried were measured. In the first trial it was shown that zearalenone concentration within sites was highly variable at that time of the year, however, urine-patch and dung patch sites yielded significantly higher quantities of zearalenone. Zearalenone appeared to be readily taken up by the ryegrass plant through the roots and translocated into the young growing tissue of the plant. The distribution of zearalenone in the pasture and the plant are discussed with regards to zearalenone intake by the animal. The zearalenone dosing trial showed that significant levels of zearalenone, α-and α-zearalenol, zeranol and taleranol were present in the blood and urine of dosed ewes and that levels of all compounds analysed were higher in ewes grazed on pasture. Ewes grazing pasture had a significantly lower (P<0.05) ovulation rate than ewes grazed on chicory. The third trial showed that chicory was effective in reducing the levels of free zearalenone present in the ewe around the time of mating with levels in ewes grazed on chicory being significantly lower (P<0.05) in both the urine and blood, than in ewes grazed on grass pasture. There were no significant differences in reproductive performance. Zearalenone levels in the pasture were generally lower in 1995 than in previous years and might have reduced possible differences in reproductive performance between ewes on the different feed types. The implications of higher zearalenone concentrations in the pasture are discussed with regards to reproductive performance and the use of chicory as a feed prior to mating. Further research is required to identify and clarify links with zearalenone and metabolites produced in pasture and reproductive dysfunction in ewes.
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    A study of some aspects of sexual behaviour in the sheep (Ovis aries) : a thesis in partial fulfilment of the requirements for the degree of Master of Science in Zoology at Massey University
    (Massey University, 1973) Ross, Kenneth Richard
    Studies of sheep mating behaviour have, in the past tended to concentrate on the statistical parameters associated with mating behaviour and the oopulatory act (Bermant et al., 1969,a,b,c; Haughey, 1959; Hulet et al., 1962,a,b,c; Inkster,1957; Lambourne,1956; Lindsay and Ellsmore, 1972; Lindsay and Robinson,196l; Pepelko and Clegg,l965) and have all but ignored a close analysis of the motor acts of the ram and the ewe and their relationship to one another. The result is a body of knowledge having immediate application, especially in efficiency studies, but lacking a firm foundation so that studies could still be found as recently as 1967 on sheep mating behaviour, that gave brief descriptions of some motor acts that were, and remained, unnamed (Mattner et al.,1967). Banks (1964) drew attention to this situation and although his study did much to rectify this, it was by no means complete. The acoount of Hafez et al. (1969) can be viewed in much the same light - though providing more descriptive information than many other investigations (Bourke, 1967; Lindsay,1966; Lindsay and Fletcher, 1972) including several of his own (Hafez,1951; Hafez, 1952), certain basic inadequacies were still apparent. The inadequacies of previous descriptive studies became especially evident during the preliminary stages of the present study, when it became obvious that the sexual behaviour of sheep was much more complex than the earlier studies had indicated.
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    A study of management practices and productive performance on a sample of hill country sheep farms in north-east Wairarapa : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Farm Management at Massey University
    (Massey University, 1984) Parker, W. J.
    The research reported in this thesis was directed towards the analysis of the inter-relationships between management practices and productive performance on a survey group of 30 north-east Wairarapa hill country farms. The initial survey, which essentially concentrated on the period between ewe weaning and tupping, incorporated a combination of mail and personal interview techniques. In addition, sample liveweights of ewe hoggets in autumn (April 1) and of two tooth and mixed aged (MA) ewes prior to mating were obtained to describe production levels more objectively. Preliminary results and appanent opportunities for improving the management of existing production systems were presented to the survey farmers as a group. As a consequence, a follow-up mail survey directed at management practices and associated production levels during the winter and spring (post-mating to weaning) was implemented in August 1983. Sample liveweights of ewe hoggets at spring shearing and ewe and lamb weights at weaning were collected. Results were discussed with the 29 participating farmers. Descriptive statistical methods (e.g. frequencies, cross-tabulation) were initially used to describe farm physical characteristics and the management systems employed. Subsequently, multivariate techniques (regression and MANOVA) were used to estimate the relative importance of different management strategies and farm physical characteristics on system performance. The major recommendation from this study is that increased emphasis should be placed on rearing ewe lambs so that they achieve a liveweight of 35kg or more by May 1. The average April 1 ewe lamb liveweight on the survey farms in 1983 was 30.2kg (range, 18.7 - 40.0 kg). Other recommendations include mid-October or later commencement of calving, delaying ewe mating until April 1, earlier weaning of lambs and calves in dry summer areas (8-10 weeks and 12 weeks average age respectively) and increasing the winter rotation lengths of ewes. It is suggested that a large proportion of the potential level of production on hill country can be realised inexpensively through relatively small changes to existing management practices (such as those mentioned above) and associated management control of production system performance.
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    A study of the reproductive performance of two year-old Romney and Border Leicester X Romney ewes after differential feeding and gonadotrophin treatment : 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, 1975) Eastwood, Kenneth Charles
    The reproductive performance of 207 first-cross Border-Leicester x Romney (Border-Romney) and Romney 2 year-old ewes was compared after they grazed in the autumn for 2 months at 2 levels of feeding and treatment with 0, 600 or 1200 i.u. Pregnant Mare's Serum Gonadotrophin (PMSG). To induce and synchronise oestrus at the start of the breeding season, intravaginal progestagen sponges were inserted for 14 days. PMSG was injected on day 12 or 13 after first heat and ewes were then run with entire Southdown rams. Each ewe was laparotomised within a week of PMSG injection to record the ovarian activity. Peripheral blood was collected from a sample of ewes at intervals throughout pregnancy and progesterone concentration determined. The number and weight of lambs at birth and at weaning were recorded. High-plane ewes gained 1.39 kg and low-plane ewes lost 1.51 kg over the 2-month period of differential feeding. Following sponge withdrawal and at the next cycle 80% and 90% of all ewes were in oestrus and of these 77% and 80% were mated over 2 and 3 consecutive days, respectively. PMSG did not affect the degree of synchronisation of oestrus but treatment with the drug, improved feeding and injection on day 12 rather than 13, each reduced the mean cycle length. Border-Romney ewes had higher natural ovulation rate, lambing performance and response to PMSG than Romney ewes. PMSG reduced (16%) the conception rate at first service, proportionately more ewes returned to service at prolonged intervals (>20 days), and this "carry-over" effect reduced the incidence of ewes that later became pregnant. There was marked variation in ovarian response to PMSG. However, litter size increased with up to 5 ovulations per ewe despite an increasing percentage of potential lambs lost. Uterine capacity in terms of both number and weight of lambs born was greatest in Border-Romney ewes but exceeded natural ovulation rate in both breeds. Potential reproductive performance is, therefore, limited by the number of eggs released and in practice management factors before and at mating and selection of ewes with a propensity for higher ovulation rates should be emphasised. Lambs born to Border-Romney ewes were heavier at birth and grew more rapidly to weaning. It is likely that part of this superiority of growth rate was related to a greater milk production by these crossbred ewes and this possibility should be investigated further. Diagnosis of ewes with either single- or multiple-bearing pregnancies on the basis of blood progesterone levels (measured either early or late in pregnancy) was found to be no more accurate than other methods (rectal-abdominal palpation, ultrasonics and radiography) currently available. Variation in lamb birthweight within birth rank appeared to limit the accuracy of diagnosis of single- or multiple-bearing ewes late in pregnancy. Liveweight of the ewe and weight of lamb born were antagonistic in their effects on blood progesterone concentration.