The equine intestinal microbiome—the population of bacteria, fungi, yeast, and protozoa residing in the large intestine and cecum—could be considered its own dynamic, intricate, and powerful ecosystem thriving within the horse’s gastrointestinal (GI) system. While researchers originally thought the microbiome’s composition could be breed-specific and, therefore, had the potential to influence horse health and behavior in ways not yet realized, this didn’t turn out to be the case upon further exploration.

According to an international group of researchers led by Núria Mach, PhD, from INRA, AgroParisTech, Universite Paris-Saclay in France, “Understanding gut microbiota similarities and differences across breeds in horses has the potential to advance approaches aimed at personalized microbial modifications, particularly those involved in improving sport athletic performance.”

Intestinal microbiota has multiple roles in equine health, such as aiding in digestion and nutrient absorption, vitamin and fatty acid synthesis, protecting the horse from infectious microorganisms, stimulating the immune system, and providing energy to the horse by fermenting forage.

The magnitude of this microscopic power is further demonstrated by the fact that there are approximately one billion microorganisms per gram of ingesta in the cecum. To date, scientists have identified approximately 108 genera of bacteria in the equine gut.