While yeast products have been around for many years being added quite regularly to beef, dairy and poultry feed, it is only recently that the use of yeast culture has been considered for addition to horse feeds.
What is yeast culture? Yeast culture by definition is the dried product composed of yeast, and the media it was grown on, dried in such a manner as to preserve the fermenting activity of the yeast.
The benefit of the yeast culture comes from the metabolites produced during the fermentation process. It is suggested that the metabolites stimulate the bacteria in the hind gut of the horse, increasing their activity which results in an increase in digestion of feeds by the bacteria. The increase in activity is a result of changes in the bacteria population found in the hind gut. Research found that the bacteria which digest fiber in the hind gut of the horse increased in numbers when the horses were supplemented with yeast culture. This increase in numbers can result in more nutrients from the feed being available to the horse. Research has shown that horses fed diets supplemented with yeast culture digested more of the dry matter and fiber than did unsupplemented horses. The digestion of fiber in the horse results in the production of volatile fatty acids which the horse uses as a source of energy.
The addition of yeast culture in feeding programs for young growing horses, broodmares and performance horses has been evaluated. While not all research has shown statistically significant improvements a number of positive results have been found when yeast culture was fed.