Evaluation of Systematic Breeding Programs for Lactating Dairy Cows: A Review

Abstract Observing cows in estrus and inseminating them at the optimum time are necessary steps for effective reproductive management of a dairy herd. However, larger herd sizes can lead to reproductive inefficiency and decreased profits on dairy farms. Synchronization of estrus behavior through pharmacological control has been used to improve reproductive efficiency. Methods of synchronizing estrus were originally devised to decrease the time spent detecting estrus; however, systematic breeding programs are now being used for convenience and efficiency in reproductive management. Systematic breeding programs provide an organized approach for administering artificial insemination (AI) at first service. Moreover, reproductive management is based on a methodical approach for the entire herd rather than for the individual cow. Targeted Breeding TM (Pharmacia-Upjohn, Kalamazoo, MI) consists of a series of three PGF 2α injections at 14-d intervals. For convenience, injections are usually given one day a week to all cows that surpass the specified target date. The PGF 2α injections may be continued until detection of estrus and AI or fixed-time AI. Ovsynch consists of a GnRH injection at a random stage of the estrous cycle, followed by PGF 2α 7 d later, a second GnRH injection 36 to 48h after PGF 2α , and timed AI. Research has shown that both Ovsynch and Targeted Breeding TM can improve reproductive performance over that of traditional programs.