Control of ovulation in the cow

Abstract

1. Cows and heifers were injected shortly before slaughter with an extract of horse pituitary or with pregnant mare serum gonadotrophin.2. These substances were administered at different times of the cycle or in pregnancy; various doses were given simultaneously with removal of the corpus luteum.3. A series of animals were given 1500 or 5000 i.u. at intervals from 5 days before to 3 days after expression of the corpus luteum; up to thirty ovulations were so obtained.4. A small number of cows have been treated and left to calve; there have been several twin and triplet births.