Horses are made to eat small portions at a time, of suitable forage or browsing material. Our modern feed management often looks very differently. Often horses have limited access to food, getting only one or two large (concentrate) meals per day and spending extended periods with nothing to eat. However, the conclusions of all the studies into feed management consistently keep pointing in the same direction: it would seem that horses are most healthy and happy when their feed management most closely reflects their nature. Recent research into broodmare fertility showed the same results. 

This research was conducted at the Tunisian national stud at Sidi Thabet. One hundred mares were divided into two groups. The mares were all adults, aged 4-21 years old. Mares in one group (restricted feeding) were given one meal of 10kg of hay in their overnight stables. The mares in the other group (continuous feeding) were given half their hay during the day and the rest at night in their stables. All mares were stabled 17 hours a day and turned out 7 hours. They also received barley as daily feed. 

All mares were checked for receptiveness by teasing, but also by rectal palpation and ultrasound. Each mare was then either covered naturally or artificially inseminated with fresh or frozen semen. Of the mares in the ‘continuous feeding’ group 81% conceived, with only two abnormal estrus cycles occurring. Out of this 81%, 59% conceived at the first service. Of the mares in the ‘restricted feeding’ group, 55% conceived, of which 32% conceived on the first service, and 16 had an abnormal estrus cycle. 

The horses all shared the same hours of turnout and were given the same about of hay and concentrates in total. The difference in the feeding of the hay was the only variable. Researchers suggested that feeding hay semi-continuous (divided over the day) resulted in less stress and a better function of the mare’s digestive system than when the hay was fed in one single portion. Their recommendation was to keep the mares as close to their natural feeding behaviours as possible to maximise their fertility.