Nutrition influences the winter ovarian inactivity in mares

摘要

In the northern hemisphere, most of mares show an anovulatory period from approximately October to May. Duration of this winter inactivity depends on their age and their physiological state [1]; young mares (<4 years old) and adult mares (>=4 years old) which had suckled a foal on the previous summer present a longer winter inactivity than adult barrens. This effect is probably due to a negative energy balance. For both young and lactating adult mares growth and lactation are privileged to the detriment of reproduction. Compared to other species, the effects of nutrition on reproductive function is poorly studied in equine. However, some authors [2-7] have clearly shown that a nonrestricted nutrition at the end of winter or in spring decreases the length of anovulatory period. The goal of our experiment was to demonstrate that a food energy restriction induces winter ovarian inactivity in autumn and counteracts the photostimulating effect for advancing the first ovulation in the next spring.