You've reached the Virginia Cooperative Extension Newsletter Archive. These files cover more than ten years of newsletters posted on our old website (through April/May 2009), and are provided for historical purposes only. As such, they may contain out-of-date references and broken links.

To see our latest newsletters and current information, visit our website at

Newsletter Archive index:

Virginia Cooperative Extension - Knowledge for the CommonWealth

Get those cows bred before summer heat becomes a challenge

Dairy Pipeline: April 2006

John F. Currin
Extension Dairy Veterinarian
(540) 231-5838; email:

Pregnancy rates in Virginia dairy herds drop significantly once summer heat stress arrives. It is important to get cows pregnant before summer heat makes them more difficult to breed and now is the ideal time to work on ensuring as many pregnant cows as possible. With timed AI programs like OvSynch and CoSynch, it is possible to get semen in cows without relying on heat detection. There is no reason open cows should not get at least two breedings before summer. If you are having trouble catching cows in heat, consider enrolling all cows that are open at herd check into a timed AI protocol (OvSynch or CoSynch.) For years we have given cows that are open at herd check and have a CL a dose of prostaglandin and then watched for heats. On most farms only 40-60% of those cows would be found in heat and bred in the next 7 days. By putting these cows on a timed AI program, you can ensure that 100% of cows will get semen in them within 10 days. Timed AI programs are not the complete answer to getting cows pregnant on all farms. Timed AI programs work best in herds where the heat detection is the limiting factor for reproduction.

On many farms heat detection becomes a challenge when spring crop work keeps people busy and away from the cows. What timed AI programs do provide is the opportunity to ensure that cows are not culled due to an insufficient number of breedings. Even if you are not currently using a timed AI protocol, you should consult your veterinarian to see if doing so will help you get semen in more cows before summer heat arrives.

Visit Virginia Cooperative Extension