OVULATION SYNCHRONIZATION (OVSYNCH) IN LIMOUSIN COWS

Tania Todorova, Petar Petrov, Iancho Todorov

Abstract: In 1995, a hormonal protocol was introduced that precisely synchronizes the timing of ovulation in lactating dairy cows (Hoard’s Dairyman, August 25, 1995). Because this protocol synchronizes ovulation rather than estrus, it was called Ovsynch, and it is now commonly referred to by that name. Ovsynch begins with an injection of GnRH that can be given to the cows at any stage of the estrous cycle. Seven days later, an injection of prostaglandin F2α (PGF2α) is given followed, two days later, by a second injection of GnRH. Cows then receive a timed AI between 8 and 24 hours after the second GnRH injection without regard to estrus behavior. Our research shows that conception rates in Limousine cows Ovsynch are similar to conception rates to AI after a detected estrus. Out of 17 cows, after one treatment, 15 were found pregnant after rectal examination (88.2%). Four cows were treated twice in a row and 2 became pregnant (50%). Another 3 were treated for a third time and one became pregnant. Result shows a tendency of performance depreciation with increased number of treatments. We think this is due to physiological problems (subclinical endometritis). Also the low number of treated animal, prevent us from categorical conclusion. Anyway we can recommend the method to be used in meat cows when a timed AI is needed.

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Date published: 2023-02-22