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Age-Related Changes of the Equine Gastrointestinal TractBy Kentucky Equine Research Staff · September 9, 2016

Age negatively impacts multiple body systems, especially the gastrointestinal tract. Older horses undergo changes to this long, convoluted organ system from one end to the other.

“Increased stress due to exclusion from feeding and losing its standing in the herd’s pecking order, reduced time spent eating, changes in dentition, and decreased saliva production can all limit the amount of food an older horse ingests,” explained Kathleen Crandell, Ph.D., an equine nutritionist for Kentucky Equine Research (KER).

Once feed is ingested and swallowed, some older horses experience a drop in feed utilization. For example, changes in the microbiome, particularly a decrease in some populations or deleterious increases in others, can alter the type of volatile fatty acids produced when fiber is fermented in the large intestine. In turn, this could reduce the amount of energy harvested from the horse’s diet. Further, a decreased production of B vitamins as well as vitamin K by the microorganisms that make up the microbiome can also occur. Scarring of the intestinal tract due to parasitism over the course of a horse’s life is also believed to decrease absorption of nutrients and volatile fatty acids that give horses energy.

Senior feeds, such as those produced by KER partner feed manufacturers, take older horses’ dietary needs into consideration. Senior feeds are often:

  • Made as extruded or pelleted feeds for easier digestion;
  • Include ground roughages, such as alfalfa meal and soy hulls, to improve fiber fermentation and increase energy production;
  • Have increased concentrations of protein; and,
  • Have balanced micronutrients, including phosphorus and calcium.

When served dampened, extruded and pelleted feeds reportedly help decrease the chances of choke, which is not an uncommon occurrence in older horses. Moreover, supplementing the diet with antioxidants and fish oil, such as EO•3, can also help horses remain healthy well into their 20s, 30s, and beyond.

“While this information may make it seem that all older horses are skinny and struggling to maintain condition, studies show this is not truly the case,” relayed Crandell. “Changes in body fat deposition and muscling alter how horses look as they get older, so owners need to more critically assess their horse’s condition to make sure they maintain an appropriate body condition score as they age.”

*Argo, C.M. 2016. Nutritional management of the older horse. Veterinary Clinics of North America: Equine Practice. 32(2):343-354.