The four major grains fed to horses are oats, barley, corn, and milo (sorghum). Each has its advantages, but all are considered high-density energy sources that are added to a horse's natural diet of grass.
Barley is comparable to oats as a horse feed, except that it has a lower fiber content. It is considered a heavy feed, with a great deal of energy density. The kernel is also harder than an oat kernel; barley feed needs to be rolled or crushed. However, because it is so heavy, especially after processing, barley should always be mixed with other, bulkier feeds, such as wheat bran, to avoid the possibility of colic.
Most wheat grown in the United States is used for human consumption, with just the husks left over. However, those husks are useful as a high-fiber horse feed in the form of bran. Twice as bulky as oats, bran is poorly digested, offering very little energy. But bran is good as intestinal filler, and it helps increase the amount of manure passed.
Bran is also used as a tonic for a sick or tired horse, to provide more moisture in the bowels, or for a laxative after foaling. If bran is fed dry, it should be no more than ten percent of the total ration.
Corn is a high-energy, low-bulk feed that can make a horse too fat unless fed sparingly. It must also be checked thoroughly for mold; moldy corn can kill a horse. If corn is fed, it should be mixed with other feeds - preferably high-protein and high bulk. It takes 15 percent less corn than oats to keep a horse conditioned, provided the ration is balanced with additional protein.
Crimped, Steamed, or Rolled Grains
Crimping, rolling, or steaming cracks the outer covering of the grain, making it easier to chew and digest. The food/energy value often rises when grains are processed in these ways. The proof can be seen in manure: When whole-kernel grains are fed, many kernels pass through in their entirety, without having released full nutritional value.
For horses, nutrition is derived from three categories of feed: roughages, concentrates, and supplements.
Roughages offer relatively little energy, but are high in fiber and necessary for proper functioning of the intestines. This category includes the pasture, hay, forage crops, and silage.
Concentrates are high in energy and low in fiber; they include grains and grain by-products.
Supplements are used to balance rations and make up for deficiencies in protein, minerals, or vitamins.
Oats are the most popular feed for horses. This grain is palatable to horses and appreciated by handlers for its fiber content, which is higher than either barley or corn.
Grains can become toxic if infected with fungi or molds. Ergot, a fungus, sometimes infects wheat, rye, and barley seed heads. An affected horse may slow circulation problems if small amounts of the toxin are ingested daily. Blood vessels to the feet, ears, and tail may constrict, and the horse may even lose his ear tips or ears. He may also develop gangrene in his feet and legs, leading to death.
Moldy corn pointing can occur if the horse eats feed or even pellets containing Fusarium moniliforme, a soil-borne fungus. The affected horse may become depressed, lose weight and his appetite, and be subject to bleeding disorders. A large dose is usually fatal; it may make the horse run into fences, press his head against a fence or wall, cross his legs or walk sideways, circle aimlessly, or lose other motor control as his brain deteriorates. He may die within a few hours or linger for several days.
Wheat and Wheat Bran
Wheat is usually not fed because of its high cost; if it is, it should be rolled or crushed to make chewing and digestion easier. Wheat should be fed as less than 20 percent of the grain ration, and it should be mixed with bulky grains, such as oats, or with bran to avoid colic. Wheat is as high-energy, high-protein feed, but it is low in fiber. Wheat bran, on the other hand, is high in fiber and should only be added to the ration as 10 to 15 percent of a dry ration. Wheat bran can also be fed as a bran mash to improve intestinal functioning, or it can be added as a treat to a warm mash.
Winter Nighttime Feeding
In the winter, a horse's minimum nighttime feeding should be larger than the daytime feeding (or feedings) to help him maintain energy and body heat through the cold night. He should be fed as much hay as he will eat in the overnight period; feeding less may induce him to nibble posts, bedding, or anything else within reach because he is cold, bored, and craves more roughage. If he is bedded on straw, he may even eat that, leading to possible impaction or of the digestive upset.