Performance Horse Fueling
Energy Source by Work Level
Comparison
| Nutrient | Light Work | Heavy Work | Key Function |
|---|---|---|---|
| Forage (hay/pasture) | 1.5–2% body wt/day | 1–1.5% body wt/day | Fiber digestion, gut health |
| Concentrate (grain) | None or minimal | 0.5–1% body wt/day | Starch for quick energy |
| Fat (oil) | 0.25–0.5 cup/day | 1–2 cups/day | Calorie-dense, low starch |
| Electrolytes | Free access | 2x daily | Replace sweat losses |
| Water | 5–8 gal | 8–12 gal | Hydration, thermoregulation |
Performance Feeding Flow
Performance Feed Checklist
| Feed minimum 60% of diet as forage | |
| Divide grain into 2–4 small meals per day | |
| Add fat for calories without starch spike | |
| Provide electrolytes during and after work | |
| Wait 60 minutes after grain before work | |
| Check body condition score every 2 weeks | |
| Monitor for tying up (rhabdomyolysis) | |
| Test hay for NSC content (sugar + starch) |
Horses at maintenance (no regular work) have straightforward nutritional requirements met by quality forage with appropriate supplementation. Performance horses -- those in moderate to intense work -- have elevated caloric needs that forage alone often cannot meet, requiring strategic concentrate feeding. The challenge: most performance-related metabolic disasters (tying-up/exertional rhabdomyolysis, hindgut acidosis, laminitis in horses with EMS) result from concentrate overfeeding or improper feeding timing, not from insufficient feeding. Getting performance horse nutrition right requires understanding the energy sources available, which fuels work efficiently, and what the limits of concentrate feeding are.
| Work Level | Energy Priority | Key Limit |
|---|---|---|
| Light (trail, hacking) | Quality forage adequate — no concentrate needed | Don't add grain without a demonstrated caloric need |
| Moderate (dressage, show jumping) | Concentrate 1–4 kg daily based on work intensity | Divide into 3+ meals; never exceed 2.5 kg per meal |
| Intense (racing, cross-country) | Fat supplementation + calibrated concentrate | Introduce oil / rice bran gradually over 3–4 wks |
Energy Sources for the Equine Athlete
Horses use three primary fuel systems depending on exercise intensity and duration: (1) Fat metabolism (aerobic, low-intensity sustained work like trail riding, hacking, dressage warm-up) -- the most efficient fuel source with no metabolic by-products other than CO2 and water; (2) Starch/glucose metabolism (moderate aerobic work like collected dressage, show jumping warm-up) -- efficient but produces lactate at high rates; (3) Anaerobic glycolysis (high-intensity explosive work like racing, cross-country jumping) -- very high-rate energy with significant lactate accumulation and fastest-fatigue glycogen depletion.
Forage provides long-chain carbohydrates fermented in the hindgut, producing volatile fatty acids (VFAs) -- essentially fat-equivalent fuel. A horse digesting good hay is continuously producing fuel suitable for all aerobic work intensities. The common practice of increasing grain when a horse goes into work makes sense for horses requiring more calories than forage can provide -- but grain does not make a horse "spirited" or increase aerobic performance; it increases glycogen availability for anaerobic work and body weight.
Safe Concentrate Limits
The equine stomach is small (8 to 15 liters capacity) and produces acid continuously. Large grain meals (more than 0.5 kg per 100 kg body weight per meal) exceed the small intestine's starch digestive capacity, allowing undigested starch to reach the cecum and colon. Cecal fermentation of excess starch causes acidosis, disrupts the microbiome, increases hindgut permeability (leaky gut), and triggers endotoxin release -- the mechanism behind grain overload laminitis. Divide daily concentrate allowance into 3 or more small meals; never feed more than 2.5 kg of grain in a single meal to a 500-kg horse.
Fat Supplementation for High-Performance Horses
Adding fat (vegetable oil, stabilized rice bran, commercial fat supplements) to the diet is the safest method of increasing caloric density for horses that need more energy without additional starch. Fat provides 2.25 times more energy per gram than carbohydrates. Introduce fat gradually over 3 to 4 weeks to allow hepatic and intestinal adaptation; start at 50 to 100 ml of oil per day and increase to 200 to 500 ml maximum. Rice bran provides both fat and a palatability advantage many horses prefer over plain oil.
Electrolyte Supplementation
Horses in moderate to intense work lose significant sodium, chloride, potassium, and smaller amounts of calcium and magnesium in sweat. Sweating horses in training (more than 30 minutes of work daily) benefit from electrolyte supplementation in feed or water. Provide salt (plain white salt -- 1 to 2 oz daily minimum for working horses in addition to a salt block) and consider a balanced electrolyte supplement with sodium, chloride, potassium, and calcium during heavy competition periods. Always ensure fresh water is available before and after electrolyte supplementation; electrolytes without adequate water increase dehydration risk.
Sources: Loving NS, "All Systems Go: Feeding the Performance Horse" (2006); National Research Council, "Nutrient Requirements of Horses" 6th edition (2007); Merck Veterinary Manual equine nutrition; Harris PA & Geor RJ, "Nutrition of the Exercising Horse," Veterinary Clinics of North America: Equine Practice (2009).