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Horse Care Nutrition Probiotics - Part 1
For our probiotics series, Dr. Sheila Schils from Equine Nutritional Consulting is answering all of our questions about what probiotics are and how they can help your horse. We really appreciate all the great information she's given. Check out this two-part series, and be sure to let us know what you think in the discussion section following the article!
Probiotics - Part 1
(Direct-Fed Microbial Products (DFM)) (Beneficial Bacteria)
What does the term probiotic mean?
Probiotics are products that promote the growth of useful digestive microorganisms (a.k.a. gut flora or micro flora) in the digestive tract. They help to ensure efficient digestion and maximum nutrient absorption. This means the animal will get the most nutrients from their food, which in turn, improves growth, production, and disease resistance. Probiotics have been used for many years in other livestock industries to improve feed efficiency, but have just recently been promoted by the horse industry.
Probiotics are especially useful for better fiber digestion and are administered orally. Depending on a horse's diet, it will have a different makeup of microorganisms. For example, a horse with an all forage diet will have a different amounts and kinds of microorganisms than a horse with a diet containing forage and concentrate. This is one key reason you don't want to abruptly change your horse's diet.
Sometimes a horse will have a shift in the type or balance of microorganisms. When this happens, probiotics can be especially useful to reintroduce beneficial bacteria, and to help prevent harmful (pathogenic) bacteria from taking the place of beneficial microorganisms.
Where are probiotics utilized in the horse's digestive system?
The large intestine and the cecum of the horse basically make up a fermentation vat that breaks down feed into components that the horse can utilize. This fermentation process is not a simple one, such as the breakdown of starch to sugar. Instead, it is the creation of new nutrients that the horse can use. Bacteria, yeast and protozoa are the microorganisms responsible for the fermentation, and fiber is the main foodstuff broken down by these microorganisms.
Probiotics are feed to the horse to reintroduce or increase the population of these beneficial microorganisms into the horse's digestive system. This is done because cultures must be present in a large enough quantity to achieve the desired results.
What will these probiotics do to help my horse?
Probiotics lower the pH of the gut so pathogenic bacteria have less of a chance to survive. Also, probiotics help maintain the airless environment of the gut (removing oxygen) so beneficial anaerobic bacteria can function normally. Probiotics help digest cellulose and then use the byproducts of cellulose digestion to construct vitamins (B vitamins and vitamin K).
Researchers have found an 8-10% increase in fiber digestibility in adult horses when they were fed yeast. Yeast cultures increase fiber fermentation in the hind gut, thus increasing the availability of energy. This increased energy availability is a result of the yeast stimulating the fiber fermenting bacteria to more completely digest plant cell walls. Increased protein digestion was also found in horses feed yeast (researchers found an increase in nitrogen uptake and a decrease in ammonia in the urine). A good portion of the fermenting microorganisms are also used as a high quality protein, this protein has a high content of the amino acids lysine and methionine. Yeast may increase rate of growth because of the increase in available lysine (lysine is the most growth limiting AA).
Another advantage probiotics yield is the attachment of beneficial bacteria to intestinal linings which increases the absorptive surface area of the small intestine and enhances enzyme activity to assist in digestion. For example, the large intestine is a major site of phosphorus digestion, however the horse's ability to absorb phosphorus from feed stuffs (particularly grain) is poor. Intestinal microbes are necessary here to assist in creating the enzymes necessary for phosphorus absorption. This is a common problem for older horses (Kentucky Equine Research (95) found a 20-25% improvement in phosphorus absorption).
Several other examples include:
- The specific bacterium Lactobacillus acidophilus is good at breaking down milk sugars and other carbohydrates and therefore can be useful in relieving diarrhea (scours).
- Probiotics will help reestablish the beneficial gut bacteria after antibiotic treatment or deworming
- Another bacterium, Lactobacillus acidophilus can stimulate immunity against common gut pathogens (e.g. E. coli and salmonella) because it exudes acetic acid, lactic acid and hydrogen peroxide which inhibits the growth of gas-forming bacteria such as E. coli.
- Yeast may lower heart rates and respiration as well as lower lactic acid build up (increased lactate may cause muscle spasms).
- Feeding yeast improves skeletal development due to decreased bone re-absorption (decrease in hydroxyroline concentrations)
- Also, yeast probably improves milk production, nutrient intake and absorption by foals and muscle growth.
How many different types of beneficial bacteria are there?
There are 30-40 species dominating the gut, but there are thousands of different species, which means there are billions of microbes in the horse's gut. There have been no specific studies on the exact balance of the gut bacteria of the horse.
How do you know which microbes are lacking so you can know which ones to treat?
Fortunately, it is difficult to do any harm with probiotic supplements. Those microbes that do not take "hold" will simply be flushed out of the system. There is little risk in giving probiotics as a preventative measure.
What are the types of beneficial bacteria I should be feeding my horse?
Lactobacillus acidophilus
Lactobacillus acidophilus is one strain found in the small intestine which can survive the acidity of the stomach to reach the large intestine, therefore it is a useful oral probiotics. L. acidophilus attaches to the lining of the small intestine and can prevent disease-causing organisms from binding to the intestinal wall.
Yeast Cultures (Saccharomyces cerevisiae)
Yeast are fungi or one-cell organisms that reproduce by budding. Yeast can survive and grow with or without oxygen, but grow much more efficiently with oxygen. Yeast produces carbon dioxide and energy and can ferment in an anaerobic environment. It is a good source of protein with an amino acid profile equivalent to soybeans. Yeast is also high in B-Vitamins. High selenium yeast can contain up to 2000 ppm of selenium, which may result in too high of a selenium level. Live yeast will die once it hits the digestive tract, so you want to feed yeast culture rather than active dry yeast.
About Dr. Schilis
Dr. Sheila Schils has a Master's degree in Equine Nutrition and a Ph.D. in Kinesiology/Biomechanics. She was a Professor of Equine Science at the University of Wisconsin-River Falls for 20 years. Currently, Dr. Schils runs two businesses; Equine Nutritional Consulting and Equine Rehabilitation. She has spoken nationally on the topics of equine nutrition and the biomechanics of horse and rider. She has raised warmblood horses and has been active in the horse industry as a competitive rider, receiving many national and regional awards in eventing and dressage.
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