Before exploring the benefits of yeast for horses, some appreciation is in order. Yeasts are fascinating microorganisms with over 1500 species currently identified. Yeast microbes may be one of the earliest domesticated organisms. Archeologists working in Egypt have found baking chambers for yeast-raised bread that date back thousands of years.
These organisms use organic compounds as a source of energy and do not require sunlight to grow, nor do they need oxygen in order to produce energy. Yeasts are naturally occurring on the skins of fruits and berries and on exudates like cacti, as well as in soils, on insects and on our skin. Even deep ocean environments host a variety of yeasts.
Under anaerobic conditions (without oxygen), yeast converts sugar and starches into alcohol and carbon dioxide. This process is known as fermentation. Without yeast fermentation there would be no bread, wine, beer, root beer, Kombucha, or kefir. Without yeast fermentation there would be no industrial ethanol production. A wide variety of chemicals are now produced with genetically engineered yeast, including phenolics, alkaloids, and specific amino acids like Lysine. Some biopharmaceuticals are produced from yeast, including insulin, vaccines for hepatitis, and human serum albumin.
Yeast for horses:
The two most common strains of yeast used in equine feeds and supplements are S. cerevisiae and S. boulardii. These yeasts function in the hindgut of horses helping to digest dry matter and organic matter. The yeasts are commonly fed in forms known as yeast culture or live/active yeast.
Yeast culture, also known as yeast fermentation product, has been processed so that it is heat stable and can withstand high temperatures. Yeast culture cannot colonize the hingut because it is not viable or alive. Yeast culture cannot reproduce because the yeast has been inactivated. Yeast culture is the most predominant form of yeast in feeds and some supplements.
Active yeast, also known as viable or live yeast, is capable of colonization. Several European studies highlight increased digestibility of fiber in the hindgut with live yeast. Active yeast is measured in CFUs (colony forming units) just like other active probiotics such as yogurt.
Yeast and the hindgut:
Changes to the pH of the hindgut can occur when soluble carbohydrates either from grains or grasses overload the small intestine and pass to the large intestine where microbial fermentation occurs. Rapid fermentation occurs with accumulation of lactic acid bacteria, which changes the pH of the hindgut, causing suppression of the fiber- digesting bacteria. Changes to the pH of the hindgut can cause colic, laminitis, and increased gas accumulation as the abundant lactate-producing bacteria take over.
More evidence for the benefits of yeast for horses: studies in the UK have shown that lactic acid levels were lower and cecal pH higher in horses fed a high starch diet supplemented with live yeast.
Saccharomyces cerevisiae and Saccharomyces boulardii:
- S. cerevisiae is the most widely used organism in foodstuff and industrial microbiology. S. boulardii is a close relative to S. cerevisiae, but with some notable differences.
- S. boulardii has a higher survival rate at acid pH and a greater resistance to high temperatures than S. cerevisiae. Another fundamental difference between these two yeast strains is that S. boulardii has been proven to have activity in the small intestine as well as the hindgut.
This is a byproduct of beer-making and like baking bread using S. cerevisiae yeast. It is inactivated by heat then made into powder or flakes known as brewer’s yeast. Brewer’s yeast is an excellent source of B-vitamins, GTF Chromium (glucose tolerant factor), magnesium, protein, nucleic acid, and all the essential amino acids. Brewer’s yeast, due to its inactivation, does not function as a probiotic.
Made with S. cerevisiae yeast and grown on a medium like molasses, or grains, or sugar beets. It is a de-activated yeast. Nutritional yeast is made specifically for supplementation, and does provide the same nutritional components as brewer’s yeast, but is less bitter and more palatable. It does not function as a probiotic.
If you are concerned about genetically modified organisms, check with the company to find out if their nutritional yeast is Non-GMO. Biostar uses nutritional yeast from Europe that is Non-GMO.
Selenium yeast is produced by fermenting Saccharomyces cerevisiae in a selenium-rich media. The organic form of selenium provided by selenium yeast has been shown to provide a higher bioavailability of selenium. Selenium yeast has been associated with increased ability to counteract oxidative stress with its antioxidant properties, and helps with immune response, growth, and reproduction.
When to supplement with yeast:
Live yeast improves fiber fermentative capacity and other aspects of digestion. It helps to ameliorate potentially detrimental changes to the hindgut population and environment, particularly when feeds are high in starch. It also helps reduce overpopulation of lactic acid bacteria in the hindgut as well as increase the level of activity of cellulolytic bacteria (the bacteria that break down cellulose).
Live yeast can be a supportive food for horses with hindgut ulcers, and colitis. Live yeast can be beneficial for hard-keepers, during or after antibiotic therapy, and during times of high stress such as shipping and competing.
Brewers yeast and nutritional yeast are excellent whole food alternatives to the synthetic or coal tar derivative B vitamins found in supplements and feed. These yeasts provide the B-complex vitamins, with the exception of B12, and are an excellent food source of protein, essential amino acids, and GTF chromium.
Selenium yeast is a highly bioavailable yeast which is great for recovery after hard work, and for senior horses.
- Live Yeast / Probiotic: Bio Yeast EQ
- Brewer’s Yeast: Furnace EQ, Locomotion EQ
- Nutritional Yeast and Brewer’s Yeast: Optimum EQ (and the entire line of Optimum)
- Selenium Yeast: Locomotion EQ, Rebound EQ, Optimum Senior EQ, and Optimum Senior JS.
* These statements have not been evaluated by the Food and Drug Administration.
This information is not intended to diagnose, treat, cure, or prevent any disease.