A. Fed as a concentrated source of calories, oats have been the go-to grain for horsemen for generations. They have a reputation for being a safer choice than other common grains, such as corn, barley, and wheat. This has to do with the fact that at about 45% starch, oats contain significantly less starch than the other grains, which have a starch content between 55-70%. Oat starch is also more digestible, due to its chemical structure. Both factors mean undigested starch has less risk of reaching the horse’s hindgut, where it would disrupt microbial fermentation. Should oats reach the hindgut, they provide more fiber than the other grains, potentially causing less damage to the hindgut environment.
This doesn’t mean, however, that you can feed horses unlimited amounts of oats. Large amounts of oats can still overwhelm the small intestine and its ability to digest and remove that starch, resulting in hindgut disruption. Keep meals containing oats small—less than 5 pounds per meal for an average-sized (1,100-pound) horse—and wait at least six hours between grain meals.
Another quality that makes oats favorable is their relatively high fat content for a grain, at around 6.5%. The next highest fat content in a common grain is corn, at around 4%. Oats also provide oat beta glucan, a dietary fiber that might help support gastrointestinal mucosa and stimulate the immune system.
Oats are not fortified, so horses consuming oat diets require a source of additional vitamins and minerals in their rations. This need for additional fortification of grains and a desire for simplicity in rations is ultimately what led manufacturers to develop fortified performance feeds. Feeding oats to horses is an entrenched tradition, especially among racehorse trainers. Even when feeding fortified performance feeds, many trainers still feed some amount of oats. Unfortunately, this can result in them not feeding the fortified feeds optimally.
Whether you should continue to feed oats depends on your horse, his energy requirements, and your preferred way of feeding. Oats are making a bit of a comeback among owners who desire to get back to basic feeds. However, they can complicate rations due to the need for additional supplementation.
Many horses coming off the track can be picky eaters, and oats are often very palatable. You also don’t want to change Thoroughbreds’ rations too dramatically when they come off the track. Their lean muscle mass is so high when they first leave that they often continue to need a surprising number of calories, even when not working. You may, therefore, find yourself needing to feed a large amount of concentrate feed in addition to hay to maintain condition and might decide to feed some or all of this as oats. A number of fortified feeds exist that contain oats but rely more on fat and fiber than starch. These feeds could be good options for you and your horse at this time.