| 其他摘要 | Embryo transfer (ET) has potential to increase rates of genetic improvement in domestic farm animals. Embryo transfer provided the purebred animals, and could avoid the risk of infectious diseases such as foot and mouth disease in the event of importing animals directly. ET was safe in the movement of germplasm, and also has the advantages of a low cost in getting purebred animals. However, the success of embryo transfer depended on factors associate with the embryo, the recipient and the interaction among factors of the embryo and recipient. On the other hand, the primary use of embryo transfer in domestic animals has been to amplify reproductive rates of valuable females, and the growth performance of the purebred offspring from embryo transfer was very important to evaluate the effect of embryo transfer/Development of the offspring was associated with environmental factors such as litter size, rearing condition and transfer season. Therefore, it is important to study the factors affecting pregnancy rate and development of the offspring from embryo transfer for the better realization of embryo transfer to commercial production. With a high merit for productivity provide both meat and skins, Dorper flocks should receive high priority. Embryo engineer was regarded as a useful method to amplify Dorper sheep. Considerable advances have been made in the last several years in the sheep embryo engineer, including superovulation, in vitro production, embryo frozen and transfer technology. As far as the factors affecting pregnancy rate of the embryo transfer, some reports indicated that number of transferred embryos, stage of the embryos, frozen and fresh embryos, methods for transfer affected the pregnancy rates of embryo transfer. However, there is still no study has been performed to check the effect of recipient breeds on embryo transfer of Doiper, meanwhile, the conclusions of the effect of season on embryo transfer are conflicting. The present study examines the effect of recipient breed and season on the embryo transfer of Dorper, only 1 embryo was transferred to each recipient. Pregnancy rate was used as measurement to evaluate the effect on embryo transfer. The results showed that there was no significant difference in the three recipient breeds (P>0.G5), while significant difference was found in the transfer season (PO.05), embryo transferred in fall got a higher pregnancy rate (68.6%) than spring (58.5%). Several reports in other animals including goats showed that recipient did not affect the development of the offspring form embryo transfer. This study examines the effect of the recipient weight on the pre-weaning development of the offspring by analysis the birth weigh, 1 month weight and 2 month weight (weaning weight). The results showed that recipient weight was related to birth weight of the offspring (PO.05), big recipients always born big kids, but the weights were not found significant difference between the two recipient groups two months later. The development of lambs was associated to the environmental factors, lambs was born in early spring if the embryos were transferred in fall and bom in fall if transferred in spring. The present study examines the effect of transfer season on development of the offspring, the results showed that season significantly affected the development of the new kids, there was no significant difference in the birth weight between the two groups (P>0.05), while significantly difference was found in the next development (P<0.05). |
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