The Complete Guide to Horse Nutrition: From Foals to Senior Horses

Understanding Your Horse's Digestive System

Horses are hindgut fermenters with a unique digestive system that evolved over millions of years for continuous grazing on open grasslands. Their relatively small stomach holds only 2-4 gallons, meaning they're designed for frequent, small meals rather than large portions twice daily. This evolutionary adaptation has profound implications for how we should feed our domesticated horses today.

The hindgut, including the cecum and large colon, houses billions of beneficial microorganisms that ferment fiber into volatile fatty acids—the horse's primary energy source. This delicate ecosystem requires consistency above all else. Sudden dietary changes can disrupt these microbial populations, potentially leading to serious conditions like colic, laminitis, or hindgut acidosis. Any changes to your horse's diet should be made gradually over a period of two to three weeks.

The small intestine processes starches, proteins, and fats through enzymatic digestion. However, its capacity for starch digestion is limited. When horses consume large grain meals, undigested starch can overflow into the hindgut, causing fermentation problems and dangerous pH changes.

The Foundation: Forage First

Every horse's diet should be built on quality forage—this principle applies regardless of breed, discipline, or performance level. Horses need a minimum of 1.5-2% of their body weight in forage daily. For a 1,100-pound horse, that translates to approximately 16-22 pounds of hay or pasture equivalent each day.

Grass hays like timothy, orchard grass, bermuda, and brome are ideal for most adult horses at maintenance to moderate work. They provide essential fiber without excessive calories, making them perfect for easy keepers or horses prone to metabolic issues. Quality grass hay typically contains 8-12% protein and relatively low non-structural carbohydrates.

Legume hays like alfalfa and clover offer significantly higher protein (16-22%) and calcium content. This makes them excellent choices for growing horses, lactating mares, senior horses with difficulty maintaining weight, and hard keepers in heavy work. However, the higher caloric density means you'll need to feed smaller quantities, and the calcium content requires attention to mineral balance.

Always evaluate hay quality carefully before purchasing. Look for bright green color indicating proper curing, a fresh pleasant smell, high leaf-to-stem ratio, and absolutely no signs of mold, dust, or foreign material. When possible, request hay analysis to understand exactly what you're feeding.

Water: The Most Critical Nutrient

Water is unquestionably the most critical nutrient in your horse's diet, yet it's frequently overlooked. Horses typically drink 5-15 gallons daily at rest, with requirements increasing dramatically during exercise, hot weather, lactation, or when consuming dry hay versus pasture. Dehydration can occur quickly and has serious consequences including impaction colic.

Always provide clean, fresh water in containers large enough that horses can drink deeply. In winter, consider heated buckets or tank heaters—research shows horses drink significantly more when water is maintained between 45-65°F compared to near-freezing temperatures. Monitor water intake carefully, as reduced drinking often signals health problems.

Concentrates: When and How

Many horses thrive on forage alone with minimal supplementation. However, working horses, growing youngsters, lactating mares, and hard keepers often need additional energy from concentrates to meet their nutritional demands.

When feeding grain or commercial feeds, follow these important guidelines. Never feed more than 5 pounds of concentrate per meal to prevent overwhelming the small intestine's digestive capacity. Divide daily rations into multiple smaller feedings whenever possible. Make all dietary changes gradually over 2-3 weeks. Choose feeds specifically formulated for your horse's life stage and workload rather than general-purpose products.

Essential supplements for most horses include free-choice salt to meet sodium and chloride requirements that hay and grain rarely provide. Horses without regular pasture access benefit from vitamin E supplementation, which deteriorates in stored hay. Omega-3 fatty acids from flaxseed, chia, or fish oil support coat health, reduce inflammation, and improve overall wellness.

Recognizing Nutritional Problems

Vigilant observation helps catch nutritional problems early. Warning signs include dull, rough coat or poor hoof quality, unexplained weight loss or obesity, behavioral changes like irritability or lethargy, and reduced performance or stamina.

Regular body condition scoring helps you track your horse's weight objectively, independent of seasonal coat changes that can mask condition. Aim for a score of 5-6 on the Henneke 9-point scale for most horses.

Good nutrition doesn't have to be complicated. Focus on quality forage first, clean water always, and appropriate supplementation based on individual needs. When in doubt, consult an equine nutritionist or your veterinarian to develop a personalized feeding plan that keeps your horse healthy and thriving.

The Equine Society | Dedicated to Horse Health and Welfare