Applications to Control the Estrus Cycle in Bovines via Estrus Synchronization; A Review

Abstract

Estrus Synchronization is the main application of Assisted Reproductive Technologies (ART), it helps in the control of the estrus cycle with the basic help of Hormones and adds controlled Artificial Insemination, reduction in Calving interval which saves time, labor cost and effective dairy farm management. Moreover, old reproductive management is too expensive and it becomes the root of the loss of milk and meat production, it is also costly in case of labor, feed, estrus detection, long inter calving interval, postpartum estrus detection and other disease problems. To get rid of these expensive traditional practices ART has developed many methods to control estrus cycle physiology and endocrinology. Estrus synchronization tools developed in recent breeding management of dairy herds in dairy industries have become an essential part of reproduction. Many of them rely on protocols that allow timed artificial insemination (TAI) to overcome the practical anomalies during estrus detection. Currently developed programs consist of protocols that are used for re-synchronization following first or consequent inseminations. Many programs include scheduled injections of Prostaglandin (PgF_2α) and Gonadotropin-releasing hormone (GnRH). Meanwhile, progesterone and estradiol based supplements are also required in many techniques. The main program used for synchronization is "Ovsynch" protocol. Moreover, this review is based on the introduction, history, principles, factors and methods of estrus synchronization that are mostly used for profitable dairy farming, it will assist in the understanding of the basic mechanism that is involved in the control of estrus cycle.