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Virginia Cooperative Extension -
 Knowledge for the CommonWealth

AI Without Heat Detection May Finally Be Here?

Dairy Pipeline: January 1998

by Ray L. Nebel
Extension Dairy Scientist, Reproduction
Virginia Tech

Researchers at the University of Wisconsin have developed a hormone schedule that eliminates heat detection and works with appointment AI. The hormone schedule combines the administration of GnRH (commercial products either cystorelin® or Fertagyl®) followed 7 days later with prostaglandin injection (commerical products either Lutalyse(tm) or Estrumate®) with a second GnRH injection approximately 48 hours after the prostaglandin injection. Most cows do not exhibit standing heat. Insemination should be 6 to 16 hours after the second GnRH injection. The cow's reproductive tract may not have the same tone as cows that are bred when observed in "standing" heat, but the conception rate obtained has been the same as cows visually observed in "standing" heat. If the cow is observed in heat before either the prostaglandin injection or the second administration of GnRH she should be inseminated and the remaining hormone treatment discontinued. Cows in early lactation, prior to 75 days in milk should not be administered this schedule because lower conception rates have been obtained. Additionally, this program, which has been named Ovsynch, 7-2-1, or C-L-C, is not recommend for heifers. With heifers poor conception rates were reported with an explanation that these young animals probably have not established normal follicle cycle patterns. One consideration should be price of the two hormones used for synchronization. Minimum cost per treatment of one animal will be $10.50 and may be as high as $18. One caution is that this program should be used on normal cows not just problem breeders. The animal must be cycling normally for this program to work.

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