Comparison of Gonadotropin-Releasing Hormone versus Estrogen-Based Fixed-Time Artificial Insemination Protocols in Grazing Suckled Beef Cows.

Fixed-timed artificial insemination (FTAI) protocols for beef cattle in South America are primarily based on estradiol esters and intravaginal progesterone-releasing devices (IVPD). The objective of this study was to determine the optimal gonadotropin-releasing hormone (GnRH)-based protocol as an alternative to the use of estrogen-based protocols in grazing suckling beef cows. All cows received an IVPD on the day of protocol initiation and prostaglandin F (PG) plus equine chorionic gonadotropin (eCG) treatments at the time of IVPD removal.