Forage is natural and healthy for horses. The horse evolved as a grazing herbivore, consuming small, frequent meals. Consequently, the horse's digestive system is designed to digest nutrients primarily from forages, roughages or other fiber sources that are ingested slowly and continuously throughout the day. Enzymatic digestion of protein, starch and fat occurs in the foregut (stomach and small intestine). The foregut has a relatively small capacity and functions optimally when small amounts of food are ingested slowly over time. By contrast, the large capacity hindgut (cecum and large intestine) is designed for bacterial fermentation of considerable amounts of forage, roughage or other fiber ingredients. This fermentation system is highly efficient for breaking down and releasing the available nutrients found in quality forage and fiber.
The horse's digestive system depends on a consistent and stable digestive environment for prime health and function. Microorganisms in the hindgut play the largest and most critical role in digestion. Sudden dietary changes, meal feeding of high-grain diets and lack of adequate forage and fiber are examples of imperfect feed management practices that can disrupt the microbial balance and alter the digestive process. The resulting metabolic upset can negatively affect the digestive environment and ultimately compromise a horse's health.