Variances in Reproductive Efficiency of Mares in Fat and Moderate Body Conditions Following Parturition

An increase in time to ovulation after parturition could result in economic loss if the mare does not successfully conceive within a short time after foaling. To evaluate whether a difference exists in reproductive efficiency between mares of either fat (BCS of 7 to 8) or moderate body condition (BCS of 5 to 6), 24 mares were allotted to and maintained in their respective group from late gestation until pregnancy was confirmed after breeding on the second postpartum estrus. No differences were found between the groups in the number of days to foal heat ovulation (14.4 vs. 16.2 d), interovulatory interval (22.9 vs. 24.3 d), and conception rates (91.7 vs. 83.3%; P > 0.05) for fat- and moderately conditioned mares, respectively. This suggests that mares maintained in a fleshy body condition (BCS 7 to 8) are not prone to reproductive dysfunction or lowered levels of fertility. Nevertheless, mares in a moderate body condition did lose a greater percentage of body fat after foaling as compared with fleshier mares (0.82% vs. 0.35%; P < 0.05). The significance of these results reassures breeders that mares in a fleshier body condition are not prone to demonstrate subfertility, but does allude to the fact that mares benefit by foaling at a BCS of at least 6 to avoid diminished reproductive capability that may result from the loss of body fat that occurs at parturition and in early lactation.