Variety in Horse Diets: Good or Bad?

Imagine being offered the same meal, day in and day out. Even if it started off as your favorite meal, enthusiasm for the dish would likely decline over time. Consuming only a limited number of foods every day—referred to as diet monotony—sounds pretty ho-hum and remarkably similar to how managed horses are fed.

“Diets for horses are largely determined by their owners, and many owners have an ‘assembly line’ approach to feeding horses. Throw a flake or two of hay in every stall, line up the feed bins and add a scoop of feed, a salt supplement, maybe one or two other nutritional supplements. Overall, their diets are essentially identical day after day,” described Kathleen Crandell, Ph.D., an equine nutritionist for Kentucky Equine Research.

But horse diets are supposed to be constant to avoid gastrointestinal upset, right?

A steady diet is a frequent theme in equine nutrition, but a growing body of data in this surprisingly controversial field of medicine reveals both pros and cons to diet monotony.

According to one equine nutritionist*, wild horses are trickle feeders rather than meal eaters. Further, the composition and quality of a horse’s diet in the wild naturally varies both by geography and season. As described by Davidson, studies show that horses prefer having access to multiple forages, rather than a single forage, and that offering more than one forage could decrease unwanted behavior such as eating stall bedding.

One study in humans** supports the merits of a diverse diet, reporting that a varied diet, rather than a monotonous diet, helps battle fat deposition when healthful options are offered. In contrast, research in mice*** shows that a monotonous diet may help protect against colitis by protecting the microbiota—the population of beneficial microorganisms residing in the intestine.

“A lack of variety among forages is one of the reasons that our modern concentrate feeds are formulated to supply extra nutrients. As long as a horse is eating his ration with gusto, there is probably nothing wrong with monotony. However, if a horse does not seem to relish his daily ration, then mixing it up may help perk his appetite” Crandell offered.

She added, “In horse management books written in previous centuries, some authors advocated diversity in the daily diet of the working horse to maintain interest in eating because those horses were often fed four to six times a day.”

For example, in a 285-year-old text, Gibson**** suggests adding beans or peas to a measure of oats for one of the feedings; feeding oats in the morning and evening, and boiled barley midday; and making one of the feedings a bran mash.

“Variety in diet within a day is not as much of a problem for the digestive tract as a complete change in diet from one day to the next,” noted Crandell.

Gross changes in a horse’s feedstuff should be made slowly. If a dietary change is necessary, nutritional supplements such as yeast, a prebiotic or probiotic, or hindgut buffer could help protect the microbiota.

*Davidson, H.P.B. Equine Studies Group, Waltham Centre for Pet Nutrition. The impact of nutrition and feeding practices on equine behavior and welfare. Havemeyer Workshops.

**Vadiveloo, M., L.B. Dixon, T. Mijanovich, et al. 2015. Dietary variety is inversely associated with body adiposity among U.S. adults using a novel food diversity index. Journal of Nutrition. 145(3):555-563.

***Nagy-Szakal, D., S.A. Mir, M.C. Ross, et al. 2013. Monotonous diets protect against acute colitis in mice: epidemiologic and therapeutic implications. Journal of Pediatric Gastroenterology and Nutrition. 56(5):544-550.

****Gibson, W. 1731. The true method of dieting horses. John Osborn and Tho; Longman, London, U.K.