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    Studies of castration and tailing in young lambs [microform] : influences of different methods on acute distress responses : a thesis in partial fulfilment of the requirements for the degree of Master of Science in physiology at Massey University
    (Massey University, 1991) Lester, Stephen John
    An investigation of the acute effects of several methods (rubber rings, knife and docking iron) of castrating and tailing 4 to 5 week old lambs was performed. The investigation consisted of a study of certain anatomical aspects of the sites of castration and tailing, experimental validation of the behavioural responses as indices of distress, ranking of the various methods of castration and tailing according to the acute responses and testing of the effects of handling on lambs castrated plus tailed with the knife The innervation of the external genitalia and the tail was described and the pattern of innervation was discussed with respect to castration and tailing. The behaviour elicited by castration and tailing was dependent upon the method used. Following rubber ring application the behaviours exhibited were increased activity, increased recumbency of which a high proportion was lateral, and these behaviours were associated with elevated plasma Cortisol concentrations and are therefore suggested to be indicative of distress. After use of the knife or the docking iron abnormal standing/walking behaviour was associated with elevated plasma Cortisol concentrations and therefore appeared to indicate distress. The behavioural and plasma Cortisol responses continued beyond the 4 hour observational period of the first experiment so a second experiment was performed. It demonstrated that the response to castration plus tailing with the knife approached completion at 8 hours. Handling of lambs to effect blood sampling did not appear to significantly affect the response. Ranking of the methods of castration plus tailing, castration only and tailing only showed that the use of the knife was apparently more distressing than any other procedure. Apparently less distressing than the use of the knife but similar to each other were castration plus tailing with the rings, castration only with the ring, short-scrotum plus tailing with the rings and castration with the ring plus tailing with the docking iron. Tailing only with the ring and tailing only with the docking iron were apparently as distressing as handling with jugular venipuncture, although it is suggested that the quality of the distress apparently experienced would have been different. Thus in order to minimise the acute effects on lambs, there is evidence that the best methods are as follows. 1. For castration plus tailing: castration plus tailing with the rubber rings, short-scrotum plus tailing with the rubber rings or castration with the rubber ring plus tailing with the docking iron. 2. For castration only: castration only with the rubber ring. 3. For tailing only: tailing only with the rubber ring or the docking iron. However there are other factors to be considered in conjunction with the above recommendations, and these are discussed.
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    The effects of uterine environment upon embryonic, fetal, neonatal and post-natal development and glucose metabolism in sheep : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Science at Massey University, Palmerston North, New Zealand
    (Massey University, 2010) Sharma, Rajesh
    Studies of humans and domestic animals have shown that there is a linkage between the neonatal and post-natal health of an individual and its uterine environment during gestation. However, very little information exists for sheep and there have been no studies that have directly examined the stage of gestation at which such effects could be introduced to the conceptus. In the present study, pure-breed embryos were transferred within and reciprocally between large (Suffolk: S) and small (Cheviot: C) breeds of sheep to establish different uterine environments; SinS (large control), SinC (restricted environment), CinS (luxurious environment) and CinC (small control) and their effects upon embryonic, fetal, neonatal and post-natal development and glucose metabolism of lambs were examined. By Day 19 of gestation, conceptuses (embryo and trophoblast) developing in a restricted uterine environment (SinC) were smaller (P<0.05) than in control (SinS). The head length of SinC fetuses was smaller (P<0.05) than in SinS fetuses on Day 55 of gestation and SinC lambs were lighter and smaller (P<0.05) than SinS lambs at birth. During subsequent post-natal life, there was no difference (P>0.05) in the growth rate of SinC and SinS lambs. The liveweight and body dimensions of SinC lambs were lower (P<0.05) than SinS lambs until 9 weeks and 12 weeks of age, respectively. Day 19 peri-implantation embryos and trophoblasts that developed in a luxurious environment were bigger than in control (CinC). However, CinS fetal size did not differ (P>0.05) from CinC fetuses by Day 55 of gestation. There was no difference (P>0.05) in the birthweight and body dimensions of lambs born from these two groups. Dimension of the placentas of SinC and SinS or CinS and CinC did not differ (P<0.05) during gestation or at lambing. Concentrations of ovine placental lactogen (oPL), progesterone, insulin-like growth factor-1 (IGF-1), glucose and free fatty acid (FFA) differed between uterine environments. During glucose challenge tests, there were no differences in the concentrations of glucose and insulin, between SinC and SinS female lambs, however, glucose concentrations declined more rapidly (P<0.05) in CinS than CinC female lambs at one year of age. It was concluded that restricted uterine environment affects embryonic, fetal and neonatal development of lambs, and that these effects perpetuates until at least one year of age; but there was no effect upon glucose metabolism. Conversely, a luxurious uterine environment enhances the early development of embryos but had no effects upon subsequent fetal, neonatal and post-natal development; however glucose metabolism of post-natal female lambs was improved. It appears that these effects of uterine environment were mediated through the trophoblast during the early embryonic period and via the placenta during subsequent gestation. oPL, progesterone, IGF-1, glucose and FFA were implicated in feto-maternal dialogue. These results suggest that uterine environment significantly influences the biology of young sheep with possible economic consequences.
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    Improving triplet lamb survival in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science at Massey University, Palmerston North, New Zealand
    (Massey University, 2010) Kerslake, Joanne Isabel
    This thesis sets out to identify physical and physiological differences between lambs of different birth ranks at birth, and to use this information to identify practical on-farm management strategies which could improve triplet-born lamb survival. Triplet-born lambs, especially the lightest-triplet-born lambs, not only had a greater capacity to lose heat but also had a reduced capacity to produce heat when compared to twin-born lambs. Due to their lighter birth weights, triplet-born lambs had lower plasma thyroxine (T4) concentrations within the first 24 hours of life than twin-born lambs, and within twin- and triplet-born litters, the lightest- and medium-triplet-born lambs had greater plasma lactate concentrations than all twin-born lambs and the heaviest-triplet-born lambs. Independent of lamb birth weight, triplet-born lambs had lower plasma tri-iodothyronine (T3) concentrations within five minutes of birth, and within twin- and triplet-born litters, the lightest- and medium-triplet-born lambs had lower plasma T4 and T3 concentrations within five minutes of birth than all twin-born lambs and the heaviest-triplet-born lambs. It was hypothesised that because triplet-born lambs had a lighter birth weight and lower plasma thyroid hormone concentrations, they would have inadequate thermoregulatory capabilities when compared to twin-born lambs. The lower rectal temperatures of triplet-born lambs within the first hour of life and the lower heat production on a per lamb basis at 24 to 36 hours of age, and the lack of difference in maximum heat production on a per kg of birth weight basis at 24 to 36 hours of age support this hypothesis. Two practical on-farm management strategies trialled in this thesis to improve triplet-born lamb thermoregulation were offering concentrate supplement during late pregnancy to improve lamb birth weights, and maternal iodine supplementation to improve lamb plasma thyroid hormone concentrations. While offering concentrate showed positive effects such as increasing lamb birth weights, colostrum uptake and triplet-born lamb heat production on a per kg of birth weight basis, the results were either inconsistent across experiments or between birth ranks suggesting additional work is required to determine the repeatability and cost effectiveness of these findings. Maternal iodine supplementation offered no iv | P a g e benefits in terms of lamb birth weights, plasma thyroid hormone concentrations or lamb heat production. Further investigations identified that lamb birth weights, thyroid hormone concentrations, glucose and NEFA concentrations are positively associated with maximum heat production at 24 to 36 hours of age. Practical on-farm management strategies which could target these physical and physiological factors may improve triplet-born lamb heat production, and therefore the survival rates of triplet-born lambs.