Study On Superovulation Of Ewes

The technique of superovulation in sheep has been investigated for years,but the effects have not been very stabilization for many factors. This experiment of superovulation in four different breeds of sheep was done in different month during the breeding season, and the gonadotropin used was produced by New Zealand,Australia and China.The purpose of this study was to investigate factors such as month,gonadotrophin and mating system which affected the success of superovulation and to seek for an ideal method to improve the effect of superovulation in sheep.The experiment was done in June to October during the breeding season. Donors and receptors were synchronized by insertion of pessary left in situ for about 13 days. Donors were inserted by CIDR receptors were inserted by reIeasing progestogen spongs.The mating systems were different in donors after estrus. Embryos were recovered on day 6 (the onset of the estrus was day 0) and transferred to the recipient ewes within an hour. In experiment 1, there were four breeds of ewes: Doll Dorset,White Suffolk and Texel.The dosages of gonadotropin were: OPTI-STIM 10ml, produced by Australia; OvagenTM 10ml, produced by New Zealand; FSH 250IU,produced by NingBo. The procedure of superovulation was: 48h/60h before the CIDR removed,the donors were injected twice daily with FSH.0.15mg PGF-CL was injected at the same time of the third injection of FSH. Donors were checked for the onset of estrus at 12-h intervals from 24h after CIDR removal and intrauterine insemination was performed between 44 and 46h after CIDR removal in all donor ewes Recepient ewes were injected with 250 to 300IU PMSG at the same time of sponge removal and checked for the onset of estrus at 12-h intervals from 24h after sponge removal for about 3d. In experiment 2: the superovulation was done in Augest, September and October. The gonadotropin were OPTI-STIM and NingBo' FSH. The donors were Germany Merino and the superovulated dispose was same to experiment 1. But the mating system were intrauterine insemination and natural service+AI. Results of the experiment indicated:1. There was no significant difference in the mean number of ovulation, mean number of ova and mean number/rate of embryos transferable with the different gonaditropins; But the price of foreign gonadotropins were significantly higher than that of the native gonadotropin.So,the native gonadotropin was the better medicine for industrialization of ewe superovulation;2.There was no difference in the effect of superovulation for Doll Dorset,White Suffolk and Texel ewes;3. Based on the comparison of the superovulation for the Germany Merino ewes during Augest to October, the better month of superovulation for ewes was October in HeiLongjiang;4. The better time of intrauterine insemination to higher fertilization rate was between 44 to 46h; 5. The pregnancy rate was highest when the synchronization difference between donor and recipient ewes was 0h and +12h; 6. The oestrus rate of the donors was 96.43(27/28) and the pregnancy rate was 82.14%(23/28) after operation of the donors. It indicated that superovulation had no significant effect on the reproductive ability of the donor ewes..Master candidate: Qi Meiyu Major:Animal Genetics Breeding&ReproductionSupervisor: Prof. Li Wu...