The effect of oxytocin on the time of ovulation, conception, and embryonic survival in swine

Abstract

Three experiments were undertaken to assess the effect of a subcutaneous injection of oxytocin (OT, 10 IU) on the time of ovulation in 25 sows, conception rate and embryo survival in these sows, and conception rate and embryo survival in 82 crossbred gilts. The OT was given after the sows were detected in estrus (exp. 1) and after the first artificial insemination (AI) in exps. 2 and 3. The effect of a single AI or a second AI 18 h later on embryo survival in the gilts also was assessed. The gilts were from either a control (C) line or a line selected (S) for minimum backfat at market weight. In sows, OT versus no injection (NI) had no effect on the time of ovulation, as determined by transrectal ultrasonography (TU) when the injection was given at the detection of estrus (OT, 43.4 ± 3.4 h; NI, 47.3 ± 4.1 h), or after the first AI (OT 43.6 ± 3.2 h; NI 40.5 ± 3.0 h). Oxytocin had no effect on embryo survival in sows (OT, 78.1 ± 4.0%; NI, 76.4 ± 4.0%) or gilts (OT, 79.4 ± 3.0%; NI, 83.2 ± 2.2%). The number of inseminations had no effect on embryo survival (single, 80.3 ± 2.6%; twice, 82.0 ± 2.7%). Embryo survival was lower in S gilts (77.1 ± 2.8% vs. C, 87.1 ± 1.5%, P = 0.0092). These results show that OT had no effect on the time of ovulation in sows or embryo survival in sows or gilts. In gilts embryo survival was not altered by a second AI. Embryo survival was reduced in gilts selected for minimum backfat. Key words: Oxytocin, artificial insemination, ovulation, embryo survival