Horses evolved to eat frequent, small roughage meals throughout the day, so why do we only feed them twice?

Take a minute and picture horses in the not too distant past or in the wild today. They have no access to grain (concentrate) meals, and they graze for a substantial portion of the day. For managed horses, however, it is common to feed them two meals per day made up of a portion of concentrates and a serving of hay. Some of the more intensively managed horses have limited access to daily turnout and pasture, which means they might spend the bulk of their days in a stall without food between their meals.

“What we’ve done, without bad intention, is taken a continuous-feeding animal and turned them into meal-feeding animals,” explains Anthony Blikslager, DVM, PhD, Dipl. ACVS, professor of equine surgery and gastroenterology at North Carolina State University’s College of Veterinary Medicine, in Raleigh.

Even if those quality meals provide all the calories and nutrients a horse needs, they are not the healthiest option based on the horse’s gastrointestinal (GI) structure and function.

“How and when a horse is fed is just as important as what a horse is fed,” says Laurie Lawrence, PhD, professor in the department of animal and food sciences at the University of Kentucky, in Lexington. 

In this article we’ll review some of the basic features of the equine GI tract, describe why less frequent meal feeding can be detrimental to your horse’s health, and discuss alternative feeding management strategies.

The Gut: A Brief Overview

When on pasture, horses graze about 60% of their time, or 14 to 16 hours per day. This means horses continuously consume small amounts of forage, which provides a constant trickle of food to the stomach.

Because horses evolved as these grazing animals, their stomachs are quite small. The stomach only holds 3-5 gallons (18 liters), representing only 7-8% of the capacity of the entire digestive tract. Forage consumed during grazing moves relatively quickly through the stomach and small intestine to the hindgut (the cecum and large intestine), where bacteria and other microorganisms that make up the intestinal microbiome ferment it. Fermenting fibrous feeds is what provides horses with the bulk of their energy for bodily processes. 

Because fermentation is so important, perhaps it is not surprising that the hindgut is large compared to the stomach. The cecum has a capacity of 7-10 gallons (26-38 liters), while the large intestine holds a whopping 20 gallons (75 liters).

Why Feeding Infrequent Meals is Detrimental to Horse Health

Water Shifts and Colic

Typically, owners go out to the barn in the morning and feed horses a meal of concentrate with a “side” of forage.

“This type of meal moves rapidly through the small stomach and along 70 feet of small intestine to reach the hindgut within three to four hours,” says Blikslager.

The hindgut, however, is expecting fibrous material, not the highly fermentable sugars found in concentrates.

“If you ferment concentrate it creates a lot of soluble sugars, which draw a very large volume of water into the hindgut from the circulatory system and extracellular fluid,” says Blikslager. “It’s an unbelievable amount of water, about 150 liters or 40 gallons, being pulled into the large intestines in a very short period of time.” 

That excess water does one of two things: It causes diarrhea (evidence of colitis) and dehydration, or the body resorbs it all from the large intestine, leaving the horse at risk of impaction with the dried, fermenting ingesta that remains in both the cecum and large intestine.

“It’s just not a good idea to have all that water flux,” says Blikslager. “With a more sensible meal, the water fluxes are much more subtle. Many horses don’t deal with those fluxes well.”

Equine Gastric Ulcer Syndrome

In addition to being small relative to the horse’s size, the equine stomach is also unique because it secretes acid all day, every day. This is unlike a human stomach that only secretes acid when there is food in it.

“When a horse is fed roughage, it buffers the acid,” explains Blikslager. “But if you meal feed then it doesn’t buffer the acid, and horses are at risk of developing ulcers in the upper or squamous region of the stomach.”

Indeed, researchers have shown that intermittent feeding, high sugar and starch intake, and prolonged time without forage access are all risk factors for squamous disease (Galinelli et al., 2019). More specifically, a low forage intake (less than 1% dry matter per ideal body weight) and high sugar/starch intake (greater than 2 grams/kilogram body weight/meal) were associated with squamous gastric ulcers.

Changes to the Intestinal Microbiome and Leaky Gut

“Feeding horses meals with concentrates topped off with some forage is like feeding them a highly digestible food like Cap’n Crunch cereal instead of Shredded Wheat,” Blikslager says. “The horse is going to have a whole different population of organisms in the intestinal microbiome trying to ferment those two cereals. The shredded wheat will cause less of a shift in the microbiome because it is closest to the type of fiber the horse is used to.”

In contrast, Cap’n Crunch will cause a surge in a different population of microbes. The intestinal microbiome tries to ferment this type of feed, which creates inflammation.

“Inflammation in the gut causes a condition called leaky gut,” Blikslager explains.

Leaky gut occurs when the tight junctions that connect the cells forming the wall of the GI tract break down and become “leaky.” These cells and tight junctions are the only layer of protection between the inside of the intestinal tract and the horse’s circulation.

Thus, with leaky gut, GI tract contents seep between the intestinal cells into the circulatory system. Leaky gut may have far-reaching effects, including behavior changes, weight loss, poor performance, loose stool, chronic or recurrent colic, and laminitis.

Prioritize Roughage

Again, somewhere along the way, many horse owners radically altered how they feed, offering concentrate feeds with the forage component almost as an afterthought.

“We need to design our management scheme around a more continuous roughage intake rather than concentrate meals,” says Blikslager. “We want to always drive towards reducing the amount in the concentrate portion of the meal versus the amount in the hay or grazing. We should always try to think about roughage first.”

Lawrence agrees, adding, “Generally, horses should be eating forage in a nibbling situation, over the course of hours. Even if hay is offered just twice a day, it usually takes a horse a while to consume the offered amount. When hay or pasture is freely available, horses will be eating throughout the day … that is, they usually start and stop, start and stop.”

Slow feeders can help extend the time horses consume feed, and horse owners can also use round bales in their fields, especially when they are maintaining horses on dry lots or when the pastures are grazed down. Just be sure to seek a less nutrient-dense hay for any horses that are overweight or are participating in a weight-loss program.

Also bear in mind that minimizing meal feeding does not mean forage must be available 24/7.

“For example, horses that work for several hours a day are not going to be eating continuously while they are in the field or on the trail,” Lawrence says. “On the other hand, more or less continuous forage availability may be desirable for horses with nothing to do all day.”

This begs the question, does your horse even need a concentrated feed as a meal?

“True concentrates are fed to provide calories and nutrient fortification (vitamins, minerals, and sometimes protein),” says Lawrence. “If a horse is overweight, she may not even need a true concentrate. She may be fine with forage and a ration balancer that provides the nutrient fortification. When a horse is too thin or has an increased energy demand, providing a more digestible and nutrient-dense hay can increase calorie intake without increasing concentrate intake.”

“If owners still feel the need to feed a horse a meal, then we can lean more towards a pelleted feed, which has pieces of fiber,” adds Blikslager. “This will help us try and get away from soluble starch as much as possible.”

Small, Frequent Meals Improve Nutrient Digestibility and Glucose Metabolism in Horses

Researchers on a study published in 2021 found that increasing feeding frequency improved nutrient digestibility (Direkvandi et al.). They again observed that horses under natural conditions consume small amounts of high-fiber, low-starch feed per meal. They also noted that when feeding a large amount once a day, for example, the meal moves through the GI tract faster resulting in decreased nutrient absorption.

To explore this concept further, Direkvandi and colleagues studied 16 Turkmen horses fed either two, four, six, or eight meals in a 24-hour period. All horses received the same total amount of food (a mixture of 70% hay and 30% concentrate) per day regardless of schedule. The team collected fecal samples on Days 22 and 28 of the study and analyzed them for nutrient digestibility.

With increasing feed frequency, digestibility increased—notably, the digestibility of ash-free detergent fiber and ash-free neutral detergent fiber (measures of feeds’ cell walls, or structural carbohydrate components on an organic matter basis). The study authors attributed increased digestibility in the horses fed more meals per day to the decreased passage rate of feed material through the GI tract, the increased impact of digestive enzymes in the small intestine, and the increased amount of time the nutrients fermented in the large intestine.

They concluded that feeding more than two times per day increased digestibility; however, they observed no statistical difference between digestibility in horses consuming four and six meals per day.

This research team also evaluated serial blood glucose concentrations throughout Day 27 of the study. Glucose decreased significantly with increasing feeding frequency. Further, they observed a steadier state (less fluctuation) in blood glucose levels with more frequent feeding.

The researchers agreed that this state is likely to improve the well-being of horses and activity performance of a horse kept in a stall. It is comparable to the more natural condition where horses evolved to eat small and frequent meals throughout the day to spend 16-18 hours per day grazing.

Take-Home Message

“Feeding horses twice a day may be labor efficient, but it is not the most desirable situation for the horse,” says Lawrence.

“We understand why horses are fed meals, and horses should be fed to meet their caloric needs for their level of body condition and performance, Blikslager adds. “However, always thinking roughage first, then concentrate will hopefully help horse owners to think about the best approach to nutrition. There are increasingly better ways of getting roughage to horses, including slow feeding devices for the field and stall.”