Study On The Embryo Transfer In Meat Sheep

The technique of embryo transfer in ewes has been investigated for many years, but the effectshave not been very stabilization for many factors. This experiment was done in October toNovember. Four different breeds of ewes were treated with gonadotropin produced by China forsuperovulation. The purpose of this study was to investigate factors which affected the success ofsuperovulation and embryo transfer and to seek for a practical method under lower cost.Three experiments were done in donors. All of donors were synchronized by CIDR for about13 days. Experiment 1: 210IU dosages of FSH were given to maiden ewes which were WhiteSuffolk, Poll Dorset and Texel for superovulation. The procedure of superovulation was: 48h beforethe CIDR removed, the donors were injected twice daily with degressive dosage of FSH. and0.10mg PGF-CL was injected at the same time of the forth injection of FSH. Donors were checkedfor the onset of estrus at 12h intervals from 24h after CIDR withdrawal for three days and thenartifical injection or natural service was performed. Donors were injected with 500IU hCG on thefist day of estnis. Embryos were recovered on day 6 (the onset of the estrus was day 0) andtransferred to the recipients' ewes within an hour. Experiment 2:240IU dosages of FSH were givento adult ewes which were Ostfriesische, White Suffolk, Poll Dorset and Texel for superovulation.The other procedures were the same as experiment 1. Experiment 3: the donors were givendifferent dosages of FSH which were 210IU, 225IU, 240IU, 255IU according to weight. Theprocedure of superovulation was not abviously different with experiment 1 and 2Two experiments were done in recipients. Experiment 1, Receptors were inserted by releasingprogestogen sponges or the second time used imported CIDR for 13 days to synchronization estrus.They were not injected any other medicine. Experiment 2: Receptors were inserted by releasingprogestogen sponges for 13 days to synchronization estrus. Recipient ewes were injected withdifferent medicision according to groups: injected with 200IU PMSG at the same time of spongesremoved and injected with 25ug/16.7ug LHRH-A₃ or without any medicine on the fist day of estrus.Recipients were checked for the onset of estrus at 12h intervals from 24h after reIeasingprogestogen sponges or CIDR removed for three days.Results of the experiment indicated:1,There was no significant difference in the effect of superovulation for Doll Dorset, WhiteSuffolk and Texel maiden ewes treated with 210IU FSH (P＞0.05).2,There was significant difference in the effects of superovulation for ewes treated with240IU FSH. The rate of transferable embryos, fertilized ovum rate and the ova recovery rate ofOstfrisisches were higher than Poll Dorset, White Suffolk and Texel (P＜0.05).3,There was no significant difference in the ratio between FSH dose and weight onsuperovulation from 3.4 to 4.6, the effect of superovulation of the 3.4～4.0 group was higher than others(P＞0.05).4,The second time used imported CIDR was unsuitable to be used to synchronizationestrus.5,The synchronization rate of the group that the recipients injected without any medicine aferreleasing progestogen sponges removal were lower than other groups (P＜0.05); the rates oftransferable recipients were remarkable among groups(P＜0.05);pregnancy rates among groupswere not remarkable (P＞0.05).