Study On The Effect Of Superovulation And Repeated Superovulation In Awang Sheep

Awang sheep is one of the valuable livestock resources in China.As a characteristic livestock species in high altitude areas of Tibet,it will enter the national genetic resources protection list in 2021.In the same year,we had the honor to carry out strategic cooperation with Jinken animal husbandry in Changdu area of Tibet,and planned to protect the germplasm resources of Awang sheep through superovulation,embryo transfer and embryo freezing,so as to provide reference for the protection of germplasm resources of Awang sheep in high altitude areas.This experiment was completed with the cooperation of the local government and related enterprises.In this experiment,Awang sheep female livestock was used as donor,Awang sheep male livestock as ligand,and Aohu sheep female livestock as receptor.In 2021 and 2022,two years of superovulation and embryo transfer were carried out.More than one hundred Awang sheep were superovulated once,twice and three times.Through three batches of large-scale propagation,a scheme of superovulation and embryo transfer for Awang sheep was initially formed and applied to superovulation of nearly 400 Awang sheep.Our work has certain practical significance for the propagation of Awang sheep.The results are all recorded in real time on the test site.The following results were obtained after processing the data from different angles such as the technical personnel level,the number of corpus luteum obtained,the number of embryos recovered,the number of available embryos,and the breeding rams.1.There was no significant difference in the effect of trained surgical operators on the superovulation of Awang sheep(P > 0.05).2.The superovulation test of Awang sheep is scheduled to start in late September and subsequent hormone treatment will get better superovulation effect.3.The number of superovulation of Awang sheep will have a negative impact on the superovulation effect.The embryo recovery rate of Awang sheep in the same individual decreased with the increase of superovulation times.4.The available embryo rate in October and November was almost 17 percentage points higher than that in July(86.6 %,85.5 % vs 69.8 %).There was no significant difference in the average number of corpus luteum in three months,but the number of available embryos in October(6.02)and November(6.08)was significantly better than that in July(4.15).In the case of a one-year interval,there was no significant difference in the average number of corpus luteum(8.59 ± 4.43 vs 8.51 ± 4.65),the average number of embryos recovered(5.95 ± 3.47 vs 5.88 ± 3.82),and the average number of available embryos(4.54 ± 2.11 vs4.32 ± 3.03).5.There was a significant difference in the number of corpus luteum produced by the ovaries of different species of rams(P < 0.05),and there was a significant difference in embryo recovery rate(P < 0.05).6.Multiple superovulation in the same individual of Awang sheep is feasible,and the time interval is 1 year.In summary,the following conclusions were drawn : The trained skilled operators had no significant effect on the superovulation of Awang sheep(P > 0.05).The individual difference of breeding rams has a great influence on the superovulation results.There were significant differences in the number of corpus luteum and embryo recovery rate between different rams(P < 0.05).The first superovulation of Awang sheep individual should start in late September.Awang sheep in the breeding years,repeated superovulation,the interval of 1year had no significant effect on the superovulation effect,but the available embryo rate may decrease.The embryo recovery rate of Awang sheep decreased with the increase of superovulation times.