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    A study of the results of an embryo transfer programme conducted during two seasonal periods using five imported breeds of sheep : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Animal Science at Massey University
    (Massey University, 1991) Greaney, Kenneth Barry
    The overall objective of this trial was to compare embryo transfer results from two seasonal periods (out-of-season vs in-season) in order to determine the effect of the season on the different parameters of reproductive performance such as; theincidence of oestrus, ovarian response to exogenous gonadotrophins, fertilisation rates and the number of lambs born per donor ewe programmed and flushed. Five breeds of imported sheep (Danish Texel {DT}, Finnish Texel {FT}, Gotland Pelt {GOT), Oxford Down {OXD}, and the White Headed Marsh {WHM}) consisting of two age groups (14-16 month-old and 26-28 month-old) in a commercial embryo transfer programme (LambXL, Manawatu) were used. A total of 553 ewes out-of-season and 234 ewes in-season were studied. Two data sets were selected from these seasonal groups; (1) The random data set. (2) The repeat data set, which consisted of the same donor ewes in each seasonal group. Oestrous synchronisation was attempted with a double CIDR-G regime and a super-ovulatory treatment consisting of an initial PMSG injection (200-300IU) and a series of six descending doses of FSH-P (total dose 24-36mg). The ewes were inseminated intra-uterine with fresh diluted semen from a ram of the same breed on the basis of oestrous detection. Embryo recovery was attempted on day 6.5-7 after oestrous detection using a laparoscope-aided uterine flush technique. Two embryos were transferred to each synchronised recipient ewe within two hours of recovery. The incidence of oestrus for the out-of-season and in-season groups was 93.3% and 100%, for the random data set compared to 93.9% and 100% for the repeat data set, respectively. The ovulatory response to the super-ovulatory treatments was significantly affected by the interaction of the breed and age of the donor in the random data set, but the repeat data set ovulation rate was not significantly affected by any of the variables recorded in this study. This interaction was attributable to the GOT breed having a higher ovulation rate in the older age group relative to the younger age group which was the reverse trend exhibited by the remaining breeds. However, there was an overall tendency for the out-of-season ovulation rate to be higher than that in-season, 7.64CL vs 6.60CL for the random data set and a difference (out-of-season - in-season) of +2.86CL was recorded for the repeat data set. The embryo recovery rates were 53.4% out-of-season and 53.5% in-season for the random data set and a difference of -0.7 percentage points was recorded for the repeat data set. The fertilisation rate was not significantly atfected by the season with 75.5% out-of-season and 65.7% in-season from the random data set and a difference of -4.5 percentage points was recorded for the repeat data set. The yield of good quality transferable embryos was significantly affected by the season with 78.2% out-of-season and 83.7% in-season from the random data set but the repeat data set was not significantly affected by the season with a difference of -11.0 percentage points. The embryo survival rate to birth was not significantly different for the two seasonal periods with 66.3% out-of-season and 52.4% in-season of the embryos surviving to birth for the random data set and a difference of +9.7 percentage points was recorded for the repeat data set. This resulted in an average of 1.66 lambs born per donor ewe programmed out-of-season, which was not significantly different from 1.00 lambs born in-season for the random data set compared to a ditference of +0.1 1 lambs born per donor ewe programmed in the repeat data set. This work clearly demonstrates the inter-dependence of several factors affecting the number of lambs born per donor ewe in an embryo transfer programme. However it is concluded that out-of-season embryo transfer is as effective as that conducted in-season, under these embryo transfer conditions.
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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.