Equine nutritionists and veterinarians have long been preaching the importance of forage in horses’ diets. We know ample, good-quality forage is crucial to their digestive health, but why? Nathalie Trottier, Professor of animal science in Cornell’s College of Agriculture and Life Sciences, in Ithaca, New York, took an evolutionary and physiological approach to explaining the importance of forage for modern equids. The horse family Equidae adapted extremely well to grassland as they evolved from browsers to grazers over millions of years. Trottier explained this is evident in their rich fossil record, which reveals equids’ teeth, feet, and more adapted to give them an evolutionary advantage over other herbivores. As we’ve domesticated the horse throughout the past 5,500 years, she said, we’ve not only bred them selectively for performance, appearance, and temperament, but we’ve also added high-starch cereal grains and concentrate feeds to their diets in place of full-time forage. The result? An increased prevalence of gastric ulcers, dental issues, metabolic disease, and digestive upset. Trottier reviewed the horse’s digestive anatomy—from the teeth to the large intestine—and how each component is uniquely designed to process forage. Horses’ teeth erupt slowly and continuously to compensate for constant grinding (16 to 20 hours per day for some). “Grinding is important because it wears away about 2-3 mm per year to counter erupting,” she said. “Attrition from an herbivorous diet tends to keep pace with eruption rates.” Allowing horses to consume free-choice forage all day reduces their risk of uneven tooth wear and dental overgrowth, she said. Feeding concentrates, on the other hand, introduces more sugars and starches that are detrimental to dental health. Saliva is also critical to dental health because it lowers horses’ risk of developing cavities. The horse’s lower jaw evolved to be narrower than the top jaw. This allows the horse to move his jaws left and right and consume fibrous feedstuffs more effectively. horse’s stomach is the smallest segment of its GI tract. The large intestine) is designed to ferment slowly fermentable fibers. We can help it flourish by providing sufficient forages and fibers.”

When creating a feeding strategy for your horse, consider how he evolved, and focus osn a forage-first diet tailored to his gastrointestinal physiology. In doing so, you can help prevent many dental and digestive issues common among domesticated horses.