Superovulation in cattle: Effect of goat anti-PMSG serum

Sixteen heifers were superovulated using 5 000 i.u. PMSG on days 9 to 11 of the oestrous cycle (day 1 of the experiment) followed by two injections of 500 mug Estrumate 48 and 54 hours later. Eight of them were injected with goat anti-PMSG serum 5 hours after the first signs of oestrus were observed. Compared with the control group, the treatment with anti-PMSG serum resulted in a shorter heat period (25.8 vs. 51.3 hours), a higher mean number of ovulations (22.1 vs. 18.0) and a lower number of follicles over 10 mm in diameter (4.1 vs. 22.3). The mean numbers of eggs recovered in the experimental and control groups were 17.8 and 6.9, of which 70.2 and 42.0 per cent, respectively, were viable embryos. The concentrations of progesterone and 17-beta oestradiol in the blood plasma showed no significant differences between the experimental and control animals. A higher oestradiol in the control group on day 9 of the experiment was in keeping with the histological picture of the target organs and with a significantly higher number of follicles at slaughter on days 12 to 14 of the experiment.