Select Sires

What to do When Cows Don't Show Estrus in Summer Heat
Ovsynch Eliminates Heat Detection
Transcript of Select Sires' Reproductive Moment Program
on DairyLine Radio Which Aired July 25, 2002
With Mel DeJarnette, reproductive specialist

Mel, summertime can get awfully hot out there and this week you have a look at ways to combat summer heat stress.

As summer stress continues to set in, catching cows in heat becomes more and more difficult. The frequency of mounting and the intensity of estrus decreases as ambient temperatures rise. "If the cows don’t want to show heat, you can’t make them, however, as the old saying goes, if you can’t beat ‘em, join ‘em". If they don’t want to show heat in the summer, then breed them to a fixed time A.I. protocol that doesn’t require heat detection. Now is a perfect time to implement a systematic Ovsynch program if you haven’t already done so. Research suggests that Ovsynch will allow many herds to cruise through the summer months with only minor or moderate reductions in 21 day pregnancy rates compared to dramatic summer declines for heat detection based herds. However, while Ovsynch does allow for efficient reproduction management in the absence of heat detection, it’s dangerous to say that we can eliminate heat detection from the breeding programs. Fifteen to 20 percent of Ovsynch treated cows don’t read the book and come into heat between day six and day nine of treatment. If not detected, few of these early responding cows can be expected to conceive to the fixed time A.I., resulting in wasted hormones, semen, and labor. Secondly, natural heats and repeats to a previous heat are likely to occur on any given day. Without heat detection, the days to A.I. or the repeat A.I. will be increased in these animals, which translates into lost income for the operation. Rather than using Ovsynch to eliminate heat detection, we should think of Ovsynch as a safety-value type supplement to our heat detection programs that ensures timeliness of both the first insemination and of repeat inseminations when cows are diagnosed open at pregnancy check. While such a program has value year round, it will be particularly beneficial during these warm summer months. For more information on implementing an Ovsynch program in your herd, contact your local veterinarian or your Select Sires Reproductive Solutions Specialist™.

™Reproductive Solutions is a trademark of Select Sires Inc.

Copyright 1996-2002 Select Sires Inc. Last updated 12-Aug-2002.

Select Sires Inc., 11740 U.S. 42 North, Plain City, Ohio 43064 / Phone: (614) 873-4683 Fax: (614) 873-5751