Data of three first seasons of embryo transfer from two clones of the same mare

Abstract

underwent serial pregnancy ultrasound exams per rectum following transfer and 35-day pregnancy rates were recorded. Pregnancy rates were compared between recipient mares that ovulated 8-12 versus 1317 days postpartum. Study 2: Blastocysts (n 1⁄4 18) recovered from mares following insemination on their first PP ovulation were transferred transcervically into recipient mares that were either nonfoal-heat mares or nonlactating mares. The recipient mares underwent ultrasound examination per rectum and 35-day pregnancy rates were recorded. The Chi-square test was used to compare values. The results in Table I show that the 35-day pregnancy rate of recipient mares that had embryos transferred following their first postpartum ovulation was 65% (151 pregnancies/ 232 embryos transferred). There was no difference in pregnancy rates between recipient mares that ovulated 8-12 days versus 13-17 days after ovulation. The results in Table II show that the 35-day pregnancy rate of recipient mares was 83% (15 pregnancies/18 transferred foal heat embryos). In conclusion, mares on their foal heat can serve as embryo recipients. Furthermore, when embryos are recovered from donor mares inseminated on the first postpartum estrus, recipient pregnancy rates are high.