Study On The Key Technologies For Sheep Embryo Transfer In The Field

Traditional embryo transfer program includes the superovulation, later transfer of the flushed embryos into the recipients synchronized with the donors, in which oestrus detection performed once or twice daily during extended periods requires extra labour and has direct implication for nutrition management of the flock and also presents a higher sanitary risk. This purpose of this study was carried out to predict the time of estrus and ovulation , and AI was committed without heat detection, then embryos which will be transferred into recipients were flushed. This paper mainly concerning about estrus synchronization, superovulation, embryo cryopreservation and embryo transfer .the result are as follows:1. 174 recipients and 77 donors were carried out in the synchronization study, the result: different trials(long-term and short-term progesterone treatment) during seasonal estrus were performed to evaluate estrus rate .High estrus rate were achieved both in the short-term and long-term group. No significant differences were found among different progestogen (sponges with or CIDRs with progestogen) groups .Estrus rate of the three different estrus synchronizaion trials which are long-term and short-term progesterone treatment and high progesterone concentration long-term treatment are 96.00%,80.77% and 88.46% ,in which group 3 was higher than the other two groups.2. Significant result of the amount of recovering embryos(6.7, 7.7 and 10.0),the amount of available embryos(5.1, 6.1 and 9.9), in which protocol 3 was significant higher than the other two protocols(P<0.05) .All embryos flushed 6 after AI, most of embryo from protocol 2 and protocol 3 are morular and blastmere embryos, but embryo from protocol 1 were in variable stages, even 4-cells.Taking these aspects into account ,protocol 3 is the best,protocol 2 is the second ,protocol 1 is the last.3. Result of fresh embryo transfer: Different synchronizaion protocols in recipients represents an important effect on the pregnancy rate. Similar estrus rate leads to different pregnancy rate (67.35%, 77.42%, 78.61%) which is mainly because of different centralized estrus degree. Another result was about the effect of different embryos freezing methods: no significant differences were found among different embryos freezing methods between one-step and three-step freezing groups , which means that EG has little toxic to embryos ,and is worth of spreading .4. We can obtain a final embryo transfer program. Estrus synchronizaion in recipients: protocol 2; treatment (estrus synchronizaion and superovulation) in donors: protocol 3.Embryos freezed with one-step freezing method without taken off cryoprotectants , by which a acceptable result can be achieved.