Anti-Mullerian hormone and its relationship to ovulation response and fertility in timed AI Bos indicus heifers.

Abstract

This study evaluated the association between plasma anti-Mullerian hormone (AMH) concentration and fertility in Nelore (Bos indicus) heifers submitted to timed artificial insemination (TAI). At the onset of the synchronization protocol, heifers (n=289) received a subcutaneous P4 ear implant (3mg) and 2mg of oestradiol benzoate. Eight days later, the P4 implant was removed and 0.5mg of oestradiol cypionate, prostaglandin (0.265mg, i.m.) and equine chorionic gonadotropin (300UI, i.m.) was administered, and TAI was performed 48hr after ear implant removal. Ovarian ultrasound evaluations were performed to measure number of ovarian follicles, dominant follicle size and ovulation response. Pregnancy diagnosis was performed by ultrasound 30days after AI. Heifers with greater circulating AMH had more antral follicles, a smaller dominant follicle near timed ovulation and lower ovulation response to the timed AI protocol compared to heifers with lower circulating AMH. Although AMH and pregnancy outcome had a quadratic-shaped pattern, AMH was not significantly associated with fertility. In conclusion, heifers with lower AMH had larger follicles towards the end of the synchronization protocol and greater ovulation responses, whereas greater circulating AMH was unrelated to conception success.