HORMONAL INDUCTION OF SUPEROVULATION IN CATTLE

Eighty-nine cattle were treated to induce high superovulation with 3000 i.u. PMSG on day 16 of the cycle and slaughtered shortly after breeding and injection of 2000 i.u. HCG. In the 79 cattle that came in oestrus, the mean number of ovulations was 9.0. The percentage of follicles ovulating and the mean ovulation rate increased markedly as the interval between PMSG and oestrus increased from 2 to 5 days. Seventy-one percent of eggs shed were recovered; 68% of eggs recovered were cleaved. Evidence on cleavage stages attained, and on the location of eggs in the Fallopian tubes and uterus, suggests that a majority of eggs were capable of normal development. © 1968, Cambridge University Press. All rights reserved.