The effect of uterine lavage and oxytocin administration before and after breeding on fertility in mares in the first postpartum estrus

Abstract

The objective of this study was to investigate the effects of the combination of uterine lavage and oxytocin administration before and after breeding during post-partum first estrus on the pregnancy rates of mares. Thirty mares whose fetal membranes were released within the first 3 h after parturition were divided into three groups - the control (n=10), pre-breeding (n=10) and post-breeding treatment group (n=10). The uterine lavage was performed 4 h before breeding in the pre-breeding group and 4 h after breeding in the post-breeding group. The oxytocin administration was performed twice in both treatment groups intravenously - immediately after and 12 h after the uterine lavage. A sterile NaCl solution (0.9%) was administrated intravenously in the control group. In the control group there was a longer interval between parturition and first ovulation (14.6 days) compared to treatment groups (p<0.05). The pregnancy rates in the control; pre-breeding and post-breeding treatment groups were calculated as 40%, 40%, and 60%, respectively. Although early embryonic loss was not observed in both the pre- and post-breeding treatment groups, this ratio was 25% for the control group. As a conclusion, the administration of a uterine lavage (1 liter of sterile 0.9% NaCl solution +4.000.000 IU crystallized penicillin +4g streptomycin sulfate) and 20 IU oxytocin 4 h before or after breeding mares at their first postpartum ovulation shortens the day interval between parturition and ovulation. It can be assumed that breeding during foal heat can be effective in reducing uterine involution, inflammatory reactions related to breeding and embryonic death.