Reproduction, Events and Management | Control of Estrous Cycles: Synchronization of Estrus

Abstract

Estrus synchronization is an important reproductive management tool for dairy cattle production, where the majority of animals are bred by artificial insemination. Estrus synchronization minimizes problems associated with estrus detection, such as labor costs and estrus detection errors. While many synchronization programs involving one or a combination of several hormones have been developed and used on commercial farms, the basic principle of estrus synchronization involves manipulating the length of the luteal phase of the estrus cycle. The length of the luteal phase can be shortened by treatment with prostaglandin F2α or its analogues or it can be lengthened by treatment with exogenous progestogens. In addition, other hormones, such as gonadotropin-releasing hormone and estrogens, have been incorporated into some programs to reduce the spread in time of onset of estrus and to improve conception rate by manipulating follicular wave development. Although estrus synchronization may be associated with a reduction in conception rate at the synchronized estrus, overall reproductive performance can be increased due to improvement in estrus detection efficiency and accuracy. The major challenge for estrus synchronization research has been the achievement of a tight synchrony while minimizing the detrimental effect on conception rate at the synchronized estrus. Current trend is toward ovulation synchronization, which allows timed breeding without estrus detection.