Male-free environment prevents pregnancy disruption in domestic horse mares mated away of home

In a previous study (Bartoš et al., 2011) we have reported on the effects of the male social environment on the maintenance or disruption of pregnancy in domestic mares mated away from home. In this follow-up study we compare the effects of returning to a home environment including a male (or males) to which the returning mare had, or was denied, access or did not have access, with that of returning to a home environment containing only other females. As in the previous study, we used data collected from private horse owners in the Czech Republic. The probability of disruption of pregnancy was lowest when the mare was sharing an enclosure only with other mares. Incidence of pregnancy failure was highest when the mare was in one enclosure, while the male or males stayed in an adjacent enclosure and intermediate where females returned to a home enclosure and shared it with the home male(s). In addition, the probability of pregnancy disruption decreased with increasing number of foals delivered in the mare's previous reproductive history.