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Dec 28, 2003
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MO Ozarks
Producers leave a lot of conception rate on the table with a co-synch protocol, says Paul Fricke, University of Wisconsin dairy cattle reproduction specialist. A co-synch protocol calls for timed AI at the time of the second GnRH injection following the prostaglandin injection of an Ovsynch protocol.

While co-synch makes a lot of sense from a labor and cow-movement perspective, it does not mesh well with the timing of ovulation.

Research data show that it does not make physiological sense to combine Ovsynch (which calls for breeding cows 16 hours following the second GnRH injection), precisely synchronizing the time of ovulation, with a predetermined time of AI that is suboptimal, as is the case with co-synch, explains Fricke.

Recent research indicates that Ovsynch is the most logical recommendation for an optimized protocol based on the data, as well as the physiology of timing of AI in relation to ovulation, he adds.

According to University of Wisconsin research published in the March Journal of Dairy Science, first-lactation cows undergoing Ovsynch had a significantly higher conception rate (37 percent versus 31 percent) when compared to a co-synch protocol. The effect was even higher among older cows (47 percent conception rate for Ovsynch versus 25 percent for co-synch).

One of the most common approaches to Ovsynch implementation is to administer the first GnRH injection and the prostaglandin injection in the morning of the prescribed schedule, administer the second injection of GnRH two days later in the afternoon, and then schedule the timed AI for the following morning, says Fricke.

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