Frequently Asked Questions About Synchronizing Estrus and Ovulation in Beef Cattle with GnRH

A short lesson in endocrinology may help answer this question. GnRH is the abbreviation for gonadotropin releasing hormone, a natural hormone that is released from the hypothalamus in the brain. GnRH causes the release of two other hormones known as gonadotropins from the pituitary gland. Luteinizing hormone (LH) and follicle stimulating hormone (FSH) are the gonadotropins. During the normal estrous cycle, when the proper signals are sent to the hypothalamus, GnRH is released to cause the release of these gonadotropins, which have an impact on the ovary. One of these effects is the release of a high level of LH, termed an LH surge, which causes ovulation of a follicle. This LH surge also initiates development of a new corpus luteum (CL) on the ovary.