Experiment 1 evaluated pregnancy rates (PRs) when estradiol cypionate (ECP) replaced the second GnRH injection of a timed artificial insemination (TAI) protocol for lactating dairy cows. Cows were pre-synchronized with two injections of PGF2α (Lutalyse r , Pharmacia Corp., 25 mg; i.m.) given to multiparous cows (n=170) at 40 ± 3 and 54 ± 3 d postpartum (dpp) and to primiparous cows (n=201) at 6...
