Whole oats has been standard horse feed for decades. Oats can also be bought crimped, crushed, rolled, steamed or triple cleaned. Cleaning removes all dust and weed seeds. Some people feel if the oats is bruised by crimping or rolling it will be more digestible. Often owners will see what looks whole oats in the manure and assume that the horse can't digest the outer shell and the oats have gone straight through. But if you inspect the manure a little closer, you'll see that nothing is left of the inside of the oat and only the hulls are passing through whole. Also, there is a chance that crimping, rolling ect... allows the grain to deteriorate faster and lose nutritional value.