Plan Ahead for Weaning Foals

Along the timeline of a horse’s usual existence, weaning occurs early in life—often between four and six months of age. The process of removing a foal from his or her doting dam may result in a variety of physiological responses, including:

• Stress, including a concomitant increase in circulating levels of the stress hormone, cortisol;
• Undesirable changes to the immune system that could predispose foals to infection;
• A decreased appetite and temporary decrease in weight gain;
• Alterations in the microbiota that could result in diarrhea or colic; and
• An elevated heart rate.

Equine experts suggest that time and method of weaning could also impact the behavior of young horses.

“Diet and nutrition are known to influence abnormal behaviors, including crib-biting, wind-sucking, and wood-chewing in horses. It is therefore possible that weaning can also influence the future behavior of a foal,” noted Kathleen Crandell, Ph.D., a Kentucky Equine Research nutritionist.

Studies of foals at the Virginia Tech MARE Center in the 1990s suggested that supplementing the diet with fat and fiber (FF) rather than starch and sugar (SS) results in lower cortisol levels before weaning. Further, foals fed fat and fiber grazed more and appeared less stressed at the time of weaning.

A follow-up study* delving deeper into the impact of diet and behavior in young horses found similar results. In that study, foals were offered either a FF or SS diet starting at one month of age. Behavior of the foals was assessed both before and after weaning, and the amount of time spent performing specific behaviors was recorded. Behaviors included grazing, trotting/cantering, standing alert, investigating, resting, vocalizing, pawing, and grooming. Two months after weaning, temperament and tractability (teachability/learning ability) were assessed. This involved studying the foals’ reactions to a novel object or person and handling.

The key findings of this study were that FF foals spent more time investigating a novel object (an open umbrella) and a novel person after weaning than SS foals, and that FF foals were handled more easily than SS foals when attempting to cross a bridge or step onto a groundsheet.

The researchers concluded, “Overall, the horses that received the FF diet appeared less distressed immediately after weaning, and seemed calmer and more inquisitive during a range of temperament tests.”

*Nicol, C.J., A.J. Badnell-Waters, R. Bice, et al. 2005. The effects of diet and weaning method on the behavior of young horses. Applied Animal Behaviour Science. 95:215-221.