Horses eat a combination of hay created from dried grasses and legumes, supplemental grains like oats and barley, and sometimes treats in small amounts like apples, carrots and sugar cubes. The type of feed a horse eats depends on regional availability, performance needs and a horse's size.
The base of a horse's diet is roughage, usually in the form of hay made from dried grasses and legumes. Grass hays like Bermuda and Timothy offer a lower amount of protein than a legume hay like alfalfa or clover. The type of hay a horse needs depends on his energy needs. Performance and working horses need high levels of protein and are typically fed a combination of legume hay and supplemental grains. Horses kept as pets and occasional riding horses don't need the level of protein and energy in legumes, and are usually fed primarily grass hay.
Supplemental grains like oats and barley add essential fats and energy to a horse's diet. The amount and type of grain a horse eats depends on their energy needs and the quality of the hay making up their primary feed.
Horses also enjoy a variety of treats like apples, carrots and sugar cubes. Horse owners can also purchase pre-made horse cookies, which are commonly baked from a mixture of grains and molasses.