Oats are nutritious as well as palatable to most horses. Oats contain approximately 12 percent crude protein, which is an adequate amount for most adult horses. They are considered safer to feed than other grains because of their fiber or bulk, which reduces the risk of impaction colic.

Whole oats have the outer shell, or hull, completely intact and are the least processed of all the oat varieties. While the hull provides no nutritional value, it does offer additional fiber to aid digestion. Hulls also protect the inside of the oat, called the groat, from mold and insects. Intact hulls increase the time oats can be stored. Most horses find whole oats palatable, and whole oats are easy to mix with additional ingredients to create a more nutritionally complete feed.

Oats are often processed to break the hull and increase the surface area, which is thought to reduce dust and increase digestibility. The most popular form of processed oats are crimped, which means the oats are steamed and sent through a mechanical roller. However, a report from the Kentucky Equine Research Institute reports that crimped oats provide only a nominal increase in digestibility -- as little as 6 percent. Because crimping exposes the tender groats, though, most horses find this variety more palatable than whole oats. Crimped oats are a good alternative to unprocessed whole oats for older horses with tooth issues, or extremely young horses without fully developed teeth.