Induction of ovulation in anoestrous ewes

Abstract

Satisfactory control of the time of ovulation was achieved in anoestrous Border Leicester X Merino ewes primed with progesterone, and injected with pregnant mare serum (PMS), followed by chorionic gonadotrophin (HCG), but fertility was very low. Most of the ovulations occurred between 22 and 29 hours after HCG injection.Anoestrous virgin Dorset Horn ewes, 12-18 months old, were given progesterone injections for 8 days followed by PMS, or PMS and then HCG injection. Seventeen per cent lambed following insemination at the time of induced ovulation. Many ewes that did not conceive returned to heat, and some conceived as the result of mating up to 85 days after the induced ovulation, with the result that 45 per cent of all ewes eventually lambed.