Donor, Recipient and Embryo Contributions to Pregnancy in a Commercial Cattle Embryo Transfer System

Document Type : Original Article

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Department of Theriogenology, Faculty of Veterinary Medicine, Beni-Suef University, Beni Suef 62511, Egypt.

Abstract

Two experiments were designed to investigate factors affecting the risk of pregnancy in recipient Holstein heifers after transfer of in vivo produced embryos. The first experiment determined interactions of donor (n=16, multiparous Holstein cows), recipient (n=95 heifers) and embryo associated factors contributing to pregnancy establishment in recipients. Donors were superstimulated using pFSH and embryos were collected on day 7 after insemination, graded and transferred fresh to synchronous recipients. Effects of donor superovulation response (SR, high vs. low), embryo quality grade (first, second or third) and circulating progesterone in recipients at ET (High vs. low) on pregnancy rate per embryo transfer (PR/ET) were evaluated. High SR of donors was associated with higher numbers of all embryo quality grades (P<0.05). Recipient heifers receiving 2nd and 3rd grade embryos from low SR donors achieved greater PR/ET (70%), compared to recipients receiving 2nd and 3rd grade embryos from high SR donors (17.65%). In experiment 2, recipient Holstein heifers were allocated into a control (n=48) and a flunixin meglumine (FM) treated group (n=21) in which individual heifers were administered with 10 ml FM at ET to test effects of FM on PR/ET. Recipient temperament was evaluated (calm vs excitable). Excitable recipient temperament at ET was associated with lower PR/ET. Pregnancy tended to be higher (66.67% vs 60.42%) in treated recipients. Conceivably, SR influenced establishment of pregnancy in recipients depending on the quality of transferred embryos. In addition, treatment of embryo recipients with FM at ET may improve PR/ET in excitable recipient dairy heifers.

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