Studies in controlled artificial insemination of Merino sheep

A total number of 507 ewes were inseminated at the rate of approximately 100 per day for 5 days, in a factorial experiment with variables: rams (5), treatments (5), days of insemination (5), volume of semen (2). Treatments were: (1) control; (2) progesterone daily for 16 days, PMS on 17th, inseminated on teasing; (3) progesterone every 2 days, PMS on 17th, inseminated on teasing; (4) as for (2), but inseminated 2 days after PMS; (5) as for (3), but inseminated 2 days after PMS. The overall lambing rate was low (31-6 per cent.). There were significant differences between rams, treatments, and day of insemination. Relative infertility of one ram was related to high incidence of sperm with curled tails. Treatment effects were: (1) 40.8 per cent. of ewes lambed; (2) 33.7 per cent.; (3) 32.9 per cent.; (4) 30.2 per cent.; (5) 15.0 per cent. Insemination was less efficient on the first day. Volume of undiluted semen used (0.05 or 0.1 ml) had no effect.