BY GILDA V. BRYANT CELSO MARGRAF / SHUTTERSTOCK eedstock producers usually use Artificial Insemination (AI) and Embryo Transfer (ET) techniques to advance their genetic programs quickly. Marcy Ward, Ph.D., Extension Livestock Specialist at New Mexico State University, says some commercial beef producers in the western United States find it challenging to implement AI and ET because they do not have the training, facilities, or specialized labor. 40 I WORKING RANCH Artificial insemination is a proce-dure that allows the producer to trans-fer fresh or frozen semen to the cow’s reproductive tract during ovulation. Many semen companies provide tech-nicians and supplies for AI. Embryo transfer medically promotes the pro-duction of multiple eggs during a cow’s estrous cycle, then uses AI tech-niques to fertilize them. The embryos are harvested seven days after fertiliza-tion and implanted into “donor” cows that carry the embryo until birth. Estrous cycle timing is crucial for recipient cows to have a success-ful implantation. Ward reports that estrous is the 21-days between ovula-tions (estrus.) Estrus is the seven-day process when ovulation and sexual receptivity occur in cows and heifers. “The most successful AI and ET pro-grams rely on estrus synchronization protocols to ensure most cows bred in this way are cycling (ovulating),” Ward reports. Estrus synchronization medically I APRIL / MAY 2022