Studies And Applications On Embryo Transfer And Related Biotechnology In Twin Production Of Beef Cattle

Experiment 1: In Vivo Embryos Production in bovine donor: The comparison of several superovulation reults and analyze of the effect of superovulationIn the experiment, 51 donors were superovulated over 2 years period in order to investigat the effect of repeat multiple ovulation. Per donor per treatment obtained 6 uesful embryos. The effect of multiple ovulation of interval was analyzed. As a result, useful embryo and grade A embryo quantity obtained from each group was significantly different (p<0.01). The useful embryo from the group of 100~120d intervals was the best (7.56/donor.time), and the reaction was stable. Therefore, donors multiple ovulation at 60— 80d intervals can obtain reasonable result.Experiment 2: The comparison and analyze on the effect of estrous synchronization and gestation rate of recipients in bovine embryo transferIn the experiment, 178 local yellow cattle embryo transfer data were analyzed. The factors, such as age of recipients, diameter of corpus luteum, grade of embryos, transfer season were compared. Results indicated that both the abortion rate and dystocia rate were the lowest in age 2~3 group. In different corpus luteum diameter coraparison, the female calves rate (40.00%)was the highest derived from grade C embryos with the lowest abortion rate. For the different transfer season, the female calves rate was the highest(43.00% )in winter, the lowest was in summer. The abortion rate and dystocia rate were higher in spring (16.10% and 8.10% )than that in other seaons (P<0.05). The results prove that yellow cattle as embryo transfer recipients for all year around in feeding system is practical. Experiment 3: The comparison of effect of the embryo bisection transfer techniqueBisected embryos not only create identical twins, but can also improve the efficiency of embryo demi-embryos blastulated more readily and later stages tended to be the most viable, with morulae showing particularly poor development. This was supported by transfer data in the experiment to increase the number of offspring, When the technique was applied to early blastocysts and blastocysts at the day 7 during multiplication programmes of the embryo transfer. Our experiences indicate that the derived morula and blastocyst embryos...