Current concepts in synchronization of estrus and ovulation of dairy cows

Abstract

Estrus synchronization has become a routine reproductive management tool for dairy producers. Reproductive performance has decreased over the last 25 yr on dairy farms, and the lack of estrus detection or inaccurate detection are major reasons for increased numbers of days open for the average cow. Estrus synchronization methods that control both the function of the corpus luteum and the development of follicles with viable oocytes are critical to efficacy. This article reviews some of the synchronization methods used in dairy cattle, especially the recent protocols involving the use of GnRH. Conception and pregnancy rates from a series of studies using the Ovsynch protocol averaged 34.9 and 34.9%, respectively. Conception and pregnancy rates from breeding at detected estrus after PGF2α averaged 37.7 and 19.8%, respectively. Because pregnancy rates are typically below 40%, possible methods for early identification of open cows and resynchronization will be discussed.