Prebiotics and the Equine Intestinal Microbiome: Effectiveness Studied

A robust intestinal microbiome plays an integral role in the overall health of your horse. As a result, use of nutritional supplements that function as pre-, pro-, or postbiotics is popular among horse owners. Their use, however, remains questionable as studies do not uniformly support the effectiveness of certain ingredients, including Saccharomyces cerevisiae fermentation products (SCFPs).

SCFPs are produced by the anaerobic fermentation of yeast (Saccharomyces cerevisiae), resulting in the production of beneficial metabolites. These include B vitamins, amino acids, nucleotides, lipids, and organic acids.

“SCFPs are often categorized as prebiotics, which are substrates utilized as food ingredients by the microbial population in the host animal. However, we have not yet determined whether all reported health benefits of dietary SCFPs in horses are due to their prebiotic activity or alternate pathways, such as postbiotic actions,” explained Katie Young, Ph.D., a Kentucky Equine Research nutritionist.

Studies conducted in various species show beneficial effects of feeding SCFPs. For example, lactating dairy cows fed SCFPs had increased abundance of certain bacterial communities in their rumens that help minimize the effects of subacute rumen acidosis.

“This is somewhat comparable to subclinical acidosis in the horse’s hindgut, which serves as a fermentation vat,” explained Young.

In horses, hindgut acidosis occurs when the pH of the cecum and colon becomes more acidic than normal, often secondary to feeding large amounts of concentrates. Instead of digesting nonstructural carbohydrates in the small intestine, they are fermented in the hindgut. This action alters the microbiota, resulting in dysbiosis.

Hindgut buffers such as EquiShure stabilize the intestinal microbiome by helping to maintain a more consistent pH in the hindgut due to time-released buffering capability. Reducing fluctuations in hindgut acidity helps create an environment to support beneficial microbial populations and encourages proper digestion and absorption of nutrients.

To determine the effect of SFCPs on the intestinal microbiomes, 11 healthy horses were fed either a SCFP product or a placebo once daily for 36 days. Fecal samples were obtained and analyzed starting three days prior to SFCP supplementation and then again on days 3, 10, 24, and 36 after starting SCFP.

Despite the beneficial effects reported in other species, the researchers found that “no significant, consistent effect on fecal microbiota could be attributed to SCFP feeding” in horses. This may be due to the small number of horses used in the study. Instead, the individual animal had the greatest influence on the composition of the fecal microbiota.

“This means that each individual horse’s variation was significant but no significant differences were observed in the fecal microbial populations due to treatments,” Young said. “The fact that each horse has a unique, healthy microbiome is a commonly reported feature of similar studies.”

EquiShure offers horse owners a research-proven way to stabilize their horses’ intestinal microbiome in the face of acidosis. A stable microbiome helps support the horse’s immune system, provides energy for the horse’s working muscles, supplies nutrients and vitamins, and ferments indigestible fibers.

^*Lucassen, A., J. Hankel, C. Finkler-Schade, L. Osbelt, T. Strowig, C. Visscher, and H.-J. Schuberth. 2022. Feeding a Saccharomyces cerevisiae fermentation product does not alter the fecal microbiota of Thoroughbred racehorses. Animals (Basel) 12(12):1496.