Equine Probiotics and Prebiotics

Nutritional supplements designed to assist in digestion are becoming increasingly popular among horse owners. We’ve all heard about probiotics, but increasingly we are starting to see products claiming to be prebiotics. How are prebiotics different from probiotics, and do they actually contribute to improved gut health?

Probiotics have a well-established role in promoting robust gut health, and work primarily by introducing live cultures of beneficial bacteria into the horse’s gastrointestinal tract. These bacteria include bifidobacteria, lactobaccilus, and eubacteria, and are considered beneficial because they do not participate, to a significant degree, in the pathogenesis of disease. These beneficial bacteria play a vital role in breaking down non-digestible fibres for the production of volatile fatty acids, which are subsequently absorbed by the horse for energy.

Prebiotics, on the other hand, are not live cultures. Rather, they are compounds that are indigestible by the horse, so arrive relatively unchanged at the large intestine. Once there, the beneficial bacteria selectively ferment them because potentially pathogenic bacteria (such as Clostridia, Staphylococcus, Listeria and E. coli) do not have the necessary enzymes. This allows the beneficial bacteria to grow and flourish, and restrict the growth of potentially pathogenic bacteria. In essence, they feed the good bugs and allow them to grow and outcompete the pathogenic bacteria. The most common prebiotics include oligofructose and chicory inulin.

The primary benefit attributed to prebiotic supplementation is the increased population of native lactobaccilus and bifidobacteria in the colon, which reduces activity of pathogenic bacteria, and production of their toxic metabolites. This translates into reduced vulnerability of the horse to gastrointestinal disorders. Furthermore, prebiotic supplementation is associated with increased colonic surface area for absorption of nutrients and improved digestibility of carbohydrates, lipids, and proteins. The effectiveness of prebiotics is not long-lasting after removal of supplementation, and thus they need to be provided as part of the diet on an ongoing basis in order to continue accruing their benefits.