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Dairy Pipeline: December 2002
Ray L. Nebel
Extension Dairy Scientist,
Reproductive Management
(540) 231-4432
email: rnebel@vt.edu
Programs for synchronization of estrus or ovulation with timed AI eliminating visual observation are available. Pharmacological control of the cow's estrous cycle to improve reproductive efficiency is possible and practiced by many dairy producers. Methods were originally devised to decrease the time spent detecting estrus; but systematic breeding programs are also available to completely eliminate heat detection allowing all inseminations to be on a specific day of the week. However, very few Virginia dairy farms have adopted a breeding program that provides an organized approach for administering AI at first service. Synchronization programs allow for the scheduling of the entire breeding herd rather than individual cows. Many options exist for the actual timing of injections of synchronizing hormones. Hormones used in synchronization programs for lactating cows fall into three general compound categories: 1) prostaglandins (an example is Lutalyse), 2) estrogen (such as ECP), and 3) a releasing hormone (example is Cystorelin). Most of these hormones are the same as the naturally occurring compound that is circulating in the cow's blood. Most synchronization programs use a combination of these different classes of hormones to either cause the synchronization of the expression of estrus, ovulation, or release of the egg (usually without the expression of standing estrus). Rather than taking a reactive approach, waiting to identify cows in heat, the synchronization program induces either the express of estrus or ovulation and may allow for appointment breeding without the need for heat detection. The real advantage of these programs is the reduction in days to first breeding. Currently the national average for days to 1st service and average for DHI herds in Virginia is approximately 100 which can easily be reduced by 25 days with the implementation of a synchronization program. For the success of any program the timing of hormone injections and insemination should not vary from the protocol established with your veterinarian or consultant. After fifty cows have been inseminated an initial estimate of success can be evaluated and the program modified if needed. Synchronization programs for lactating cows are available and real economical advantages do exist for most herds to implement a program for all cows not just problem cows.