By Gina M. Fresquez, MS
Horse owners have been told many times to feed their horses small meals throughout the day, but most do not know the reasoning behind this recommendation. Horses are herbivores, designed by nature to graze on a variety of forages. Believe it or not, horses naturally will rarely go more than 2-3 hours without eating. This allows for the presence of food in the digestive tract at all times, which ensures healthy gut function. The horse’s anatomy confirms this recommendation by the function and design of the digestive tract, specifically the stomach.
Horses have relatively small stomachs compared to the rest of their digestive tract, taking up about 8% of the total tract. This small digestive organ can only hold approximately 3-5 gallons, and cannot process large meals efficiently. Therefore, feeding frequency for horses should be encouraged to many small meals throughout the day. A study conducted by the University of Kentucky found that when horses’ concentrate rations were spread over 8 meals per day and given free choice hay, they consumed more hay per day then when only fed 2 concentrate meals per day. This is important when recognizing the need for more forage in the diet for a healthy gut. This encourages the horse to nibble throughout the day and demonstrates how feeding grain and supplements frequently in small amounts can actually increase forage consumption.
Rapid Rate of Passage
Because of the horse’s small stomach, passage of feed through the stomach is relatively fast. This, paired with the horse’s inability to vomit, only allows the horse to pass food in one direction, which can create additional digestive upset if overloaded by too much feed at once.
The emptying of the stomach contents into the small intestine is controlled by the meal size. Horses receiving large meals only a few times a day fill the stomach much faster. This creates stomach distention which encourages rapid emptying rather than with smaller meals fed many times a day. This rapid emptying caused by larger meals can overwhelm the capacity of the small intestine, resulting in undigested feed reaching the hind gut of the horse, and causing digestive upset (like colic, hind gut acidosis or laminitis).
Continuous Gastric Acid Secretion
With most mammals, digestions begins with the production of saliva in the mouth and the act of chewing which stimulates the stomach to begin secreting gastric acid in preparation for digestion of feed to take place. Horses, on the other hand, are one of the very few animals that constantly secrete gastric acid in the stomach whether food is present or not (Murray, 1998). Since horses were naturally designed to graze on many small meals throughout the day, they generally need this constant supply of stomach acid to be consistently digesting their food. The act of chewing naturally triggers the production of saliva in the horse. This saliva helps buffer the acid and is not harmful as long as food is present. Horses produce a large amount of saliva when consuming forage, and less when consuming concentrates, grains and supplements. It is during periods of fasting or long hours between meals that the acid will build up and potentially acerbate or cause gastric ulcers. This becomes a concern especially with stalled horses fed 1-2 large meals a day and going without feed for 10+ hours at a time. This puts them at high risk for developing gastric ulcers, added stress, and according to Ohio State University, a much higher glycemic response, which is a concern for horses with insulin resistance, Cushing’s or other metabolic disorders.
Take Home Message
As horse owners, we try to manage our horses as close to those living in a natural grazing condition, but it is not always possible. This method rarely can meet the energy demands of most performance and race horses. In these cases, most common modern management practices of feeding stalled horses 2-3 times per day can lead to horses rapidly consuming their meal, leaving the rest of the day with out any food available and causing an increase in digestive upsets and problems. Horse owners are encouraged to manage their horses to have constant access to forage, utilizing pasture or slow hay feeders, as well as feed many frequent small meals of concentrates (grain and supplements) throughout the day.