Luteal Function and Pregnancy Rate in Bos taurus Heifers Treated With GnRH Prior to Timed Artificial Insemination.

The study aimed to evaluate the effects of GnRH given 34 h after progesterone (P4) intravaginal device (IVD) removal in a timed artificial insemination (TAI) protocol. In Experiment 1, 17 Hereford and Braford heifers (control, n = 7; GnRH34; n = 10) received 2 mg estradiol benzoate (EB) and a 1 g P4 IVD on Day 0 (D0). On D8, IVDs were removed and 150 μg d-cloprostenol (PGF) and 1 mg estradiol cypionate (EC) were administered.