HORSE SPECIES SYMPOSIUM: Can the microbiome of the horse be altered to improve digestion?

This research explores how altering the microbiome of a horse’s large intestine can improve its digestion. The study examines the effects of feed choices, feeding management, and the incorporation of digestive aids, like probiotics and prebiotics, in influencing the microbiome and, by extension, the gastrointestinal health of horses.

Overview of the Horse Microbiome and Challenges In The Industry

• The research starts by discussing the challenges faced in the horse industry due to intensive management practices. Some of these practices include high concentrate diets, low forage quality, meal feeding, and confinement housing. These could impact intestinal function and specifically affect large intestinal fermentation.
• The microbiome of the equine large intestine is a complex ecosystem. Any disruptions to this microbiota or their environment can lead to increased incidence of gastrointestinal disorder.

Approaches for Improving Horse Digestion

• According to the research, digestion in horses can be improved using different approaches such as feedstuff selection, forage quality, feeding management. Additionally, the inclusion of digestive aids, such as prebiotics and probiotics, could improve digestibility of equine diets and stabilize the microbiome of the large intestine.
• Probiotics, which are beneficial live microorganisms introduced orally into the intestinal tract have been widely used in horses for the treatment and prevention of gastrointestinal disease. However, comparing the data about their efficacy is difficult due to variations in choice of organism, dosage, and basal diet.

The Role and Impact of Probiotics and Prebiotics

• The research indicates that successful probiotics could work through competitive inhibition and advanced immunity. Lactic acid bacteria and yeast have been successful in horses.
• Using these probiotics improved fiber digestibility in horses, especially when fed both high-starch and high-fiber diets. High-concentrate diets supplemented with probiotics helped maintain cecal pH, decrease lactic acid concentrations, and enhanced populations of cellulolytic bacteria.
• Prebiotics like fructooligosaccharide (FOS) or mannanoligosaccharides have shown to improve digestibility when added to high-fiber diets. The use of FOS also reduced disruptions in colonic microbial populations after an abrupt change in diet, and shifted fecal VFA concentrations toward propionate and butyrate.

Potential Benefits and Conclusions

• The potential use of prebiotics and probiotics can bring greater stability to the equine microbiome. This not only impacts the digestibility of feed, but it also directly affects the overall health of the horse.
• Despite there still being many unanswered questions about the mode of action of successful probiotics, the research suggests that altering the microbiome of a horse’s large intestine could be instrumental in improving its digestive health.