Horses eat a variety of foods, such as hay, grain, grass and oats. Horses traditionally feed on grasses in the wild and have digestive systems suited for roughage. Domestic horses primarily graze on hay during the day, but many owners supplement their diets with pellets and mixtures made of molasses, oats and barley.
As with humans and other pets, the quantity and variety of food horses should eat daily varies depending on their size, location and activity level. Horses that receive little exercise, such as trail riding horses or those used for recreational riding, can subsist on diets of hay or pasture grass. Horses should ideally eat around 2 percent of their body weight in roughage daily, say experts at the Humane Society.
Horses with little access to grass and those with higher activity levels may need supplemental horse feed. Commercial horse food, however, should be administered carefully, as it is high in calories and has a high fiber content, which may upset horses' digestive systems.
For highly active horses, and those in warm climates, owners often put salt licks in horses' stalls to help them recover salt lost through sweating. Active horses and those used for breeding may benefit from vitamin and nutrient supplements. Like people, horses enjoy treats, and many owners provide healthy snacks to reward good behavior.