Synchronisation of oestrus in dairy cows using prostaglandin F2α, gonadotrophin-releasing hormone, and oestradiol cypionate

Abstract

An oestrous synchronisation protocol was developed for use in lactating dairy cows using PGF2α, GnRH, and oestradiol cypionate (ECP). In experiment 1, lactating dairy cows received two injections of PGF2α (on days 0 and 11) (PP; n = 10) or two injections of PGF2α (days 0 and 11) and 100 μg of GnRH on day 3 (PGP; n = 10). In experiment 2, cows were treated with PGP (n = 7), or PGP and 1 mg of ECP at the same time (PGPE0; n = 7) or 1 day after the second PGF2α injection (PGPE1; n = 7). In experiment 3, 101 lactating dairy cows in a commercial herd were assigned to one of three treatments; PP, PGP, or PGPE1. Follicular growth was measured by ultrasound in experiments 1 and 2. Every cow (experim..