Probiotics can influence fermentation in the horse’s hindgut by aiding in the digestion of food residues. In the hindgut, undigested food undergoes bacterial fermentation in the cecum before moving into the large intestine, where short-chain fatty acids produced in the cecum are absorbed and utilized. Probiotics may help improve digestive health, though their benefits can vary.
How Probiotics Impact Hindgut Fermentation in Horses
In horses, the main breakdown of foods by enzymes and absorption into the bloodstream occurs in the small intestine. The large intestine absorbs most of the remaining water. In hindgut fermenters, undigested food residues undergo bacterial fermentation in the cecum, a side pocket at the distal end of the small intestine, before moving into the large intestine. In the large intestine, the short-chain fatty acids produced in the cecum are absorbed and utilized.
What Role Do Microorganisms Play in Hindgut Fermentation?
Microorganisms found in the ruminal fluid ferment cellulose to acetic acid and other short-chain fatty acids, which can then be absorbed and utilized as energy sources. Protein within the cells of the leaves is also released and degraded; some is resynthesized for digestion as microbial protein in the true stomach and small intestine. Another action of ruminal bacteria is the synthesis of some water-soluble vitamins so that, under most conditions, the host animal no longer requires them to be supplied in its food.
What are the Benefits of Probiotics?
Probiotics have been studied for the prevention and treatment of a variety of gastrointestinal conditions. For example, the use of S. boulardii has been associated with a reduction in the frequency of diarrheal episodes in children with acute diarrhea. Likewise, certain strains of probiotics, such as L. rhamnosus GG, may have modest effects in reducing the duration of infectious diarrhea. L. rhamnosus GG and S. boulardii may be effective in preventing antibiotic-associated diarrhea in children and adults.
Are There Any Risks Associated with Probiotics?
Although generally considered to be safe, probiotics have been associated with severe bacteremia (bacterial infection of the blood) and fungemia (fungal infection of the blood) in patients whose immune systems are compromised.
How Efficient is Hindgut Fermentation Compared to Ruminants?
Hindgut fermenters are somewhat less efficient than are ruminants at digesting very high-fibre foods. However, only indigestible residues are fermented in the cecum, so that hindgut fermenters do not experience the inevitable energy loss that occurs when dietary carbohydrates are fermented in the rumen. Also, the smaller bulk of the cecum allows these animals to be more athletic and better able to escape their carnivore predators.
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