What Do Horses Eat? A Complete Feeding Guide From Hay to Grain

Last updated: April 2, 2026

By: Miles HenryFact Checked

What do horses eat? Most horses should get 80–100% of their diet from forage — hay and grass. Everything else is secondary. Get that balance wrong and problems show up fast: weight loss, colic, laminitis. I’m a licensed Louisiana racehorse owner (#67012) with over 30 years managing feed programs for Thoroughbreds in race training and pleasure horses — and the difference between getting it right and getting it wrong shows up faster than most new owners expect.

What Do Horses Eat? (Simple Breakdown)

Horses eat primarily forage — grass and hay — which should make up at least 1.5–2% of their body weight daily, according to AAEP nutrition guidelines. Grain and supplements are added only when needed for energy, growth, or specific health conditions. For most pleasure horses, quality hay, fresh water, and free-choice salt is a complete diet.

• Grass: The most natural food source — what horses evolved to eat. Available through pasture turnout.
• Hay: Dried grass or legumes — the foundation of most diets year-round, especially when pasture is limited.
• Grain and concentrates: Added energy for horses in hard work. Many pleasure horses need none at all.
• Supplements: Salt is essential for all horses. Other supplements fill specific gaps — most horses on good hay need very little.
• Fresh water: The single most critical nutrient. A horse without water is a horse at risk for colic.

Each of these is covered in depth below, including how much horses need, which types to choose, and how feeding changes with workload and age.

I’ve managed feed programs for active Thoroughbreds in full race training and for the Quarter Horses and pleasure horses I’ve kept at my Folsom facility for over 30 years. Feeding a racehorse and feeding a backyard pleasure horse are not the same job — the biology is identical, but the quantities, timing, and composition are very different. This guide covers what horses eat at every level, why the digestive system shapes every feeding decision, and what the most common mistakes look like.

How a Horse’s Digestive System Shapes What It Eats

Everything about how horses should be fed follows directly from how their digestive system works. Horses are hindgut fermenters — meaning most of their fiber digestion happens in the cecum and large colon, not the stomach. This creates two important constraints every feeding decision has to respect. For a full explanation of equine digestive anatomy, see our horse digestion guide.

First, the horse’s stomach is small relative to its body size — roughly 2–4 gallons in a 1,100-pound animal. It empties quickly, which means large, infrequent grain meals create acid pooling in an empty stomach and dramatically increase ulcer risk. In simple terms: horses are designed to eat small amounts continuously, not large meals twice a day. For a deeper look at how this affects feeding decisions, see our horse digestion guide.

Second, the hindgut fermentation process depends on a stable microbial population. Sudden dietary changes — switching hay types abruptly, dramatically increasing grain, or giving access to lush spring pasture overnight — disrupt that microbial balance and can trigger colic or laminitis.

Hay: The Foundation of Every Horse’s Diet

Hay is what horses eat more than anything else, and choosing the right type matters. The two broad categories are grass hay and legume hay, and most horses do best on a combination or on grass hay alone.

The general rule is that horses should eat 1.5–2% of their body weight in forage daily. For a 1,100-pound horse, that’s 16–22 pounds of hay per day if the horse is not on pasture. Horses in hard work may need 2–2.5% to maintain condition alongside their grain ration. Horses with metabolic conditions or obesity risk may need to be restricted to 1.5% of their current weight while targeting a lower goal weight.

Can Horses Eat Only Hay?

Yes — many horses thrive on hay alone with no grain. A horse at maintenance or light work on quality hay is getting most of what it needs. The addition of a plain salt block and fresh water covers the essentials. What hay-only feeding doesn’t cover well: high-calorie demands (horses in heavy work need concentrated energy beyond what hay volume can realistically provide), specific mineral deficiencies in regional hay (a hay test reveals whether a ration balancer is needed), and horses that struggle to maintain weight on forage alone. For the majority of pleasure horses, however, good hay plus salt plus water is a complete program.

Always check hay before buying and before feeding. Good hay is green-ish (some browning is normal), smells clean, and has no visible mold or dust. Musty smell, white or black spots, and excessive dust are all reasons to reject a bale. Dusty hay significantly increases respiratory disease risk, and moldy hay can cause colic or toxicosis. For a complete guide to selecting and storing hay, see our articles on how to choose hay for your horse and feeding horses hay.

Grass and Pasture: Benefits and Risks

Fresh pasture is the most natural feed source for horses and, when managed well, one of the healthiest. The problem is that domestic pastures — especially in spring and after rain — don’t behave like the varied, sparse natural grazing that shaped equine digestion. Nutrient density and nonstructural carbohydrate content can spike dramatically, which is why pasture management matters as much as what’s in the feed bucket. Aim for at least 2–3 acres of good pasture per horse.

The main pasture risk situations to manage:

• Lush spring grass and post-rain flush — highest risk. NSC levels spike, especially in April–June in the Gulf South. Limit metabolic and overweight horses to morning turnout when sugar is lower, or use a grazing muzzle.
• Stressed or frost-damaged grass — plants concentrate sugars as a stress response. Remove at-risk horses from pasture and feed hay instead until conditions normalize.
• Overgrazed pasture — increases weed and sand ingestion risk. Rotate pastures and supplement with hay when grass coverage is thin.
• Sparse dry pasture (drought) — inadequate calories; supplement with hay. In sandy soils, consider psyllium supplementation to reduce sand colic risk.
• Stable established pasture — low risk for most horses; monitor body condition in easy keepers who may gain weight even on modest grass.

Grain and Concentrates: When and How Much

Grain is an energy supplement for horses whose caloric needs exceed what forage can provide — horses in hard work, young growing horses, mares in late pregnancy or lactation, and horses that struggle to hold weight. Many pleasure horses, easy keepers, and horses on good pasture need none at all. Horses with insulin resistance or equine metabolic syndrome require particularly careful grain management — see our guide to managing equine metabolic syndrome for specifics.

Split daily grain across at least two meals — ideally three for horses in hard training. Never feed a hot, sweated horse a large grain meal immediately after work. Allow the horse to cool first, and offer water in small amounts frequently during the cooling process rather than a full bucket at once.

For horses in race training or high-performance programs, see our detailed guide to feeding racehorses for peak performance and our guide to feeding performance horses for competition and training. For underweight horses, see our guide on how to put weight on a horse.

One note on alfalfa-only feeding: a friend of mine feeds his performance Quarter Horses nothing but alfalfa cubes with free-choice access, and his horses competed well at a recent roping event in Fort Worth. It works for him — hard-working horses self-regulating on high-protein forage. I still wouldn’t recommend it for maintenance horses, where the excess protein adds metabolic load without benefit. But it’s a reminder that horses are more adaptable than the rules suggest when the basics are right.

Water: The Most Critical Nutrient

Water is the most critical nutrient in any horse’s diet. Dehydration leads to impaction colic faster than almost any other single factor, and horses can become dangerously dehydrated more quickly than most owners expect — especially in hot weather or during hard work.

Daily water requirements for a 1,100-lb horse: maintenance in mild weather requires 8–10 gallons; light work raises that to 10–12 gallons; hard training or race work needs 12–15+ gallons; Gulf South summers can push requirements to 15–20 gallons or more. Hay-fed horses need roughly 20–30% more water than horses on pasture because dry forage contains almost no moisture. Lactating mares need 15–20+ gallons daily. Always provide free-choice access — never ration water.

Cold water in winter is one of the most underappreciated colic risk factors. Horses significantly reduce their water intake when water temperature drops below about 45°F. In cold climates — or during the occasional Louisiana cold snap — heated water buckets or tank heaters are a straightforward intervention that meaningfully reduces winter impaction colic rates. Salt supplementation (loose salt free-choice, or a plain salt block) encourages drinking by maintaining thirst drive, and it’s one of the simplest and most cost-effective things any horse owner can do. For a full guide to recognizing and responding to colic, see our article on what to do when your horse colics.

Supplements: What’s Worth It and What Isn’t

The horse supplement market is large and aggressive. Most horses on a balanced diet of quality hay and appropriate concentrates don’t need additional supplementation beyond a plain salt block. The supplements that are genuinely worth considering for specific situations are a much shorter list than the industry would suggest.

One area where nutrition shows up visibly is coat quality. A dull, rough coat is often one of the first signs of nutritional gaps — particularly omega-3 deficiency or insufficient protein. For more on the link between diet and coat condition, see our guide on horse coat nutrition.

What Do Horses Eat Daily? (Real Examples by Workload)

The easiest way to understand equine feeding is to see what a full day actually looks like. Here are three real daily feeding examples for a 1,100-pound horse at different workload levels — the same horse, three very different jobs:

These are starting points — adjust based on individual body condition score, season, and forage quality. A horse that’s losing condition on these amounts needs more; one that’s gaining weight on them needs less.

How Feeding Changes by Workload

The single most important variable in what a horse eats is what it does. A horse doing nothing needs far less than a horse in hard training. Getting this wrong in either direction — underfeeding a working horse or overfeeding an idle one — creates problems that show up in performance, soundness, and long-term health.

Body condition scoring — assessing a horse’s fat cover on a 1–9 scale — is the most practical tool for knowing whether you’re feeding the right amount. A score of 4–5 is ideal for most horses. Below 4 means the horse needs more calories. Above 6 means it needs less, or more exercise, or both. Check body condition every two to four weeks and adjust feed before a problem becomes serious. For guidance on building feeding and care into a consistent routine, see our complete horse care schedule. For how feeding changes across seasons, see our guide to seasonal horse feeding strategies. For senior horses specifically, the feeding picture changes again after age 20 — see our complete guide to feeding senior horses.

Common Horse Feeding Mistakes

Most feeding-related health problems in horses come from a handful of recurring mistakes. None of them are complicated — but they’re common enough that every horse owner should know them by name. Several of these mistakes are among the leading causes of colic; if you’re not familiar with how to recognize and respond to colic, see our guide on what to do when your horse colics.

What Horses Should Never Eat (And Safe Treats)

Horses can safely eat a range of fruits and vegetables as occasional treats. The key word is occasional — treats are not a meaningful nutrition source and should not substitute for forage. The foods to avoid list is shorter but more important, because some common human foods are genuinely dangerous to horses.

Core Feeding Rules Every Owner Should Know

These rules apply across all horses, all workloads, and all feed types. They’re not complicated — but consistently following them prevents the most common and most serious feeding-related health problems.

1. Feed hay before grain at every feeding. Never offer grain to a horse that hasn’t had forage recently. Hay buffers stomach acid; grain on an empty stomach accelerates ulcer development.
2. Change diets over 7–10 days minimum. This applies to every switch — hay type, grain brand, pasture introduction. The hindgut microbiome needs time to adjust. Abrupt changes cause colic.
3. No single grain meal over 4–5 lbs. Large starch loads overwhelm the small intestine, reach the hindgut undigested, and trigger acidosis. Split large daily rations into multiple smaller meals.
4. Fresh water available at all times. Never ration water. Horses that drink less than they need are at real risk for impaction colic — particularly in cold weather when water is less palatable.
5. Feed by weight, not volume. A flake of alfalfa weighs nearly twice what a flake of Timothy weighs. The only accurate measure is a scale.
6. Let a hot horse cool before feeding. After hard work, allow heart rate to normalize before offering grain. Offer water in small amounts frequently during the cooldown — not a full bucket at once.
7. Check teeth annually. Horses with sharp points or hooks can’t chew properly, which means they can’t extract nutrition from feed efficiently. Dental problems cause weight loss that feed changes alone won’t fix.
8. Feed horses individually when possible. In group feeding, dominant horses eat too much and submissive ones eat too little. The result is weight and health imbalances that compound over time.
9. Check body condition every 2–4 weeks. Adjust feed before problems develop. A horse losing weight slowly is much easier to correct than one that has become significantly underweight.
10. Never feed moldy or dusty hay. Mold causes colic and toxicosis. Dust causes heaves and other respiratory conditions. When in doubt, reject the bale — the cost of bad hay is always higher than the cost of replacing it.

For guidance on raised versus ground feeding, see our article on raised vs. ground feeding and our complete horse care schedule.

FAQs: What Do Horses Eat?

Conclusion

According to guidelines from the American Association of Equine Practitioners, forage should make up the majority of a horse’s diet.

What horses eat is simpler than the supplement aisle suggests: hay and water first, grain only when the workload justifies it. The complexity is in the details — which hay, how much, when to add grain, how to manage seasonal pasture risk, and how to adjust as workload and age change. Getting those details right is what separates a horse that thrives for 30 years from one that develops chronic health problems in its teens.

The most useful thing any horse owner can do is learn to read body condition accurately and check it regularly. Feed the horse in front of you, not the horse you think you have. A horse that was at ideal weight in October may need significantly more feed by February, and a horse that gained through a lush spring pasture may need a real reduction heading into summer.

If you want to improve your horse’s feeding program, start with one step: weigh your hay and check body condition this week. That alone catches most problems early — before weight loss becomes significant, before a metabolic issue develops, before the vet bill arrives. If you get forage, water, and consistency right, you’ll prevent more problems than any supplement ever will.

For deeper guidance on specific aspects of equine nutrition, see our complete feeding library: how to choose hay for your horse, feeding horses hay, feeding senior horses, seasonal horse feeding strategies, feeding racehorses for peak performance, feeding performance horses for competition, and raised vs. ground feeding.

What does your horse eat — and has your feeding program changed as its workload or age shifted? Share your setup in the comments. I wrote every one, and it helps other horse owners avoid the same mistakes.

Sources

• National Research Council — Nutrient Requirements of Horses (6th ed.): nap.edu
• American Association of Equine Practitioners — Equine nutrition guidelines: aaep.org
• University of Minnesota Extension — Hay in horse diets: extension.umn.edu
• UC Davis School of Veterinary Medicine — Equine nutrition: vetmed.ucdavis.edu

This article provides general educational information about equine nutrition. Consult a licensed veterinarian or equine nutritionist for diet recommendations specific to your horse’s health status, workload, and regional conditions.

Miles Henry

About Miles Henry

Racehorse Owner & Author | 30+ Years in Thoroughbred Racing

Miles Henry (legal name: William Bradley) is a professional horseman based in Folsom, Louisiana. He holds Louisiana Racing License #67012 and has spent over three decades managing Thoroughbreds at premier tracks including Fair Grounds, Delta Downs, and Evangeline Downs.
Expertise & Hands-On Experience: Beyond the track, Miles has decades of experience in specialized equine care, covering everything from hoof health and nutrition to training protocols for Quarter Horses, Friesians, and Paints. Every guide on Horse Racing Sense is rooted in this “boots-on-the-ground” perspective.
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