USE OF HUMAN GONADOTROPIN IN SUPEROVULATION OF SOUTHDOWN SHEEP

Human chorionic gonadotropin (hCG; 500 IU) was administered to 12 supe rovulated Southdown ewes. Intravaginal pessaries containing 45 mg fluo rogestone acetate were inserted in all ewes and remained in situ for 1 4 days. One day prior to pessary removal, all ewes received a 1000 IU injection of PMSG. Group I ewes received no further treatment, whereas group II ewes received a 500 IU injection of hCG at first detection o f oestrus. Heat detection was done by parading an aproned ram once in a day at 10:00 h. The ewes in heat were mated with an intact ram. Corp ora lutea (CL) and unovulated follicles (over 2.5 mm in size) were cou nted at laparotomy on day 5 or 6 post-mating in both groups. Group II ewes showed a marginal increase in ovulation rate and number of unovul ated follicles but the differences were non-significant (P < 0.05). Th ese results indicate that hCG is not essential for inducing multiple o vulation in Southdown sheep. (C) 1997 Elsevier Science B.V.