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Domestication of Horses Alters Intestinal MicrobiomeBy Kentucky Equine Research Staff · December 21, 2017

The horse’s intestinal microbiome plays many important roles in maintaining overall well-being. The microbiome supports immunity; protects bacterial overgrowths; produces energy through fermentation of short-chain fatty acids; and synthesizes vitamins, among other roles.

Researchers know the intestinal microbiome becomes established early in the life of a foal and various life events change its composition a horse matures.

Weaning, exercise, certain disease conditions, transport, diet, and even the natural ageing process can alter the intestinal microbiome and in some cases, negatively affect the overall health of the horse or foal,” explained Kathleen Crandell, Ph.D., a nutritionist for Kentucky Equine Research (KER).;

One recent study* reported that domestication also altered the microbiome. Researchers believe that domestication resulted in major alterations in both lifestyle and diet that are now potentially harmful to horses.

To explore this theory, fecal samples were collected from different populations of Przewalski’s horses—the only horses alive today not successfully domesticated by humans—and from domestic horses residing on grasslands. Microbiomes in these samples were analyzed, and the authors found that fecal microbiomes were distinctly different and more diverse in Przewalski’s horses than domesticated horses. Further, a subsample of Przewalski’s horses born in captivity had a strikingly less diverse microbiome than those born in natural reserves.

The importance of an abundant and diverse microbiome cannot be disputed. Consistent management, including avoiding abrupt changes in diet and providing ample forage, is a cornerstone of maintaining a healthy gut. Administering a hindgut buffer such as EquiShure, a time-released nutritional supplement that moderates pH and stabilizes the microbiome in the hindgut, can help maintain a healthy population of microorganisms in the hindgut, especially during times of stress.

As always, consult with your veterinarian or a KER nutrition consultant before introducing any new supplement to your horse’s ration.

*Metcalf, J.L., S.J. Song, J.T. Morton, et al. 2017. Evaluating the impact of domestication and captivity on the horse gut microbiome. Scientific Reports. 7(1):15497.