Oestrous cycle length and plasma progesterone concentrations following administration of prostaglandin F-2α early in the bovine oestrous cycle

Abstract

Twice daily i.m. injections of PGF-2 alpha on Days 3 and 4 of the bovine oestrous cycle inhibited progesterone secretion by the corpus luteum and induced precocious oestrus. Injections given less frequently or earlier in the cycle did not induce precocious oestrus but twice daily injection on Days 2 and 3 or Day 4 appeared to inhibit progesterone secretion without affecting oestrous cycle length.