Ovulation time in superovulated ewes during the non-breeding season.

摘要

17 ewes were treated for 12 days with vaginal sponges impregnated with FGA. To the superovulation group of 9 ewes, an intramuscular injection of 20 mg porcine FSH was given 48 h before sponge removal, and 500 IU equine chorionic gonadotropin (eCG) was given 24 h after the FSH injection. The 8 ewes of the control group were given 500 IU eCG 24 h before sponge removal. The time of ovulation was assessed by repeated observation of the ovaries in both groups of ewes using a laparoscope. Observations were commenced 24 h after sponge removal, and were conducted every 6 h for a total of 60 h. The intervals between sponge removal and the onset of oestrus and ovulation were significantly shorter in the superovulation group than the control group. There were significant differences in ovulation rate between superovulated and control ewes. In 9 superovulated ewes, 12, 53 and 27% of the total 99 ovulations occurred 0-24 , 36-42 and 42-48 h after sponge removal respectively. The study indicates that a singleFSH injection combined with 500 IU eCG induces high synchrony (80%) of ovulation at 36-48 h after sponge removal in ewes treated during the non-breeding season.