Retained placenta in Friesian mares: reproductive performance after foal heat breeding versus breeding in a subsequent heat

Postpartum reproductive performance was studied in 54 Friesian brood mares with and 50 without retained placenta. Retained placenta was defined as failure to expel all fetal membranes within 3 hours after the delivery of the foal. The group of mares with retained placenta was subdivided into mares in which the placenta had been removed manually (n=30) and mares in which it was not (n=24). Within each group, reproductive performance after breeding in the foal heat and breeding in a subsequent heat was compared. Age of the mares, number of mares treated with antibiotics after insemination, and number of mares treated with prostaglandins were recorded. The interval between delivery and conception, efficacy rate, seasonal pregnancy rate, pregnancy rate after first insemination, pregnancy loss rate, and fooling rate did not differ between the mares with, and without retained placenta or between the mares with and without manual removal of the retained placenta. Within each group, the pregnancy rate after first insemination did not differ between breeding for the first time in the foal heat and breeding for the first time in a subsequent heat. It is concluded that reproductive performance did not differ between 1) Friesian mares with and without retained placenta and, 2) Friesian mares with and without manual removal of the placenta. With regard to reproductive performance, retained placenta and manual removal of the placenta are not valid reasons to avoid foal heat breeding in Friesian mares.