By nature, a horse is a grazer. Its digestive system is geared for utilizing forages—pasture and hay. Attempts to turn horses into grain guzzlers usually backfire. Yet, some circumstances, such as performance or racing, require a horse to consume large quantities of energy from grains, fats, and/or grain by-products. The reason these feeds are needed is because they provide more energy per pound than forage, and horses hard at work need more energy than they can obtain from forages alone. But, even horses that require high-energy diets need forage. All horses need some forage in their diet (at least 1% to 1.5% of body weight daily) to keep their digestive tracts functioning normally.

Energy—Carbohydrates furnished by forage and grain/grain by-products are the primary sources of energy for horses. Fat, which is 2.25 times more energy dense than carbohydrates, can also provide an important source of energy. Energy needs are dictated by class of horse and activity level. For instance, working horses need more energy compared to their “idle” counterparts. When providing energy, particularly in the form of concentrates, remember horses are individuals. Metabolic rates vary between breeds and between horses within breeds. This is evidenced by the differences in horses’ ability to maintain body weight when working at the same activity level and fed identical rations. Some horses may gain weight, some maintain weight, and others can even lose weight when fed exactly the same ration. Obviously, feeding more dietary energy than needed results in an overweight horse and too little energy, a thin horse.

Protein—Protein is essential for the formation of all body cells, especially muscle, enzymes, blood, hormones, hooves, and hair cells. Young horses are more responsive to protein quality in their rations compared to mature horses. This is due to their higher requirement for certain amino acids (lysine and methionine) needed for growth. Protein needs decrease as horses mature. All mature horses have practically the same protein requirement. The exceptions are pregnant and lactating broodmares and hard-working horses.

Minerals—Nutrient balance is critical in mineral nutrition. Minerals interact with one another. An excess of one often creates a greater need for another. Normally, one only thinks mineral deficiencies cause severe problems. In the horse world, mineral excesses and imbalances are probably responsible for more problems than those caused by mineral deficiencies. Indiscriminate use of minerals can be devastating to young, growing horses.

Developing good, strong bones involves more than just calcium and phosphorus. Other minerals, as well as many other nutrients, are involved in bone formation. And, mineral requirements are not restricted to bone development. Many body functions and processes are dependent on minerals.

Vitamins—Even though vitamins are needed in very small amounts, their necessity should not be ignored. Vitamins are biological catalysts, functioning in hormones and enzymes. Vitamins also help prevent damage to tissues, such as the skin and gut lining. They are needed for proper growth, development, health, and reproduction in all animals.

Concentrated Energy Sources

When forage alone will not meet energy needs, fats and/or grains should be added to the ration. Fats and oils can be fed at up to 10% of the total ration. Horses fed fats are less likely to suffer from digestive and metabolic disorders, such as colic, founder, tying-up, and gastric ulcers, than horses fed large amounts of grains. Stabilized rice bran (20% fat) and vegetable oils (corn, soybean) are efficiently digested by horses and are excellent sources of energy. Oils are easier to digest when supplied as part of a grain mix or pelleted feed than when top-dressed over feed. Stabilized rice bran is very digestible and can be top-dressed or mixed into grains or pelleted feeds.

Oats are the traditional feed for horses and are the best choice of the cereal grains for several reasons. Oats are very palatable and are the best nutrient-balanced grain, containing about 53% starch, 12% protein, 5% fat, and 12% fiber. Most importantly, the starch in oats is easily digested (83%) by enzymes in the foregut. Therefore, oat starch doesn’t contribute to starch overload in the hind-gut like corn and barley starches do. Oats should be clean, but don’t need to be processed, except for horses with poor teeth (very young, sick, or old horses).

Corn sometimes has a bad reputation as a horse feed and for good reasons. Corn is more energy dense and heavier than oats, so a direct substitution of corn for oats will lead to overfeeding. Also, corn is not balanced for nutrients. It contains about 71% starch, 8% protein, 4% fat, and only 2% fiber. But, worst of all, the starch in corn is not well digested in the foregut, unless the corn is ground and pelleted or extruded. Most of the starch from whole or cracked corn (70%) is not digested in the foregut and proceeds to the hindgut where it is rapidly fermented. That process produces lactic acid, which lowers the pH and kills many beneficial fiber-digesting bacteria. Dying bacteria release toxins, and the result can be a horse with colic and/or laminitis resulting in founder. For these reasons, corn must be processed for all horses, and should not make up more than 25% of a pelleted feed. Grain screenings often contain potentially lethal mycotoxins and should never be used in horse feeds.

Barley (65% starch) has a hard kernel that horses cannot easily chew, so it is usually rolled prior to inclusion in horse rations. However, even the starch in rolled barley has a low pre-cecal digestibility (about 21%) in horses. Therefore, oats are a much better choice for horses than barley.

While sweet feeds come in many formulas, they have several common ingredients—molasses (usually 4-12%), oats, shelled or cracked corn (in widely varying amounts), and a pellet containing vitamins, minerals, and possibly protein. Sweet feeds have been the number one concentrate choice of both horse owners and horses, yet they are detrimental in several ways. The molasses is rapidly converted into sugar in the foregut, contributing to an increase in blood sugar or ‘sugar high’ that interferes with performance ability. The unprocessed corn is not digested in the foregut, leading to complications in the hindgut (see above). Also, sweet feeds have a short shelf life, cake badly in the winter, attract flies in the summer, and are expensive based on the nutrients provided.

Pelleted feeds are also available in many formulas. When made by a reputable company, they can contain high-quality by-products from the food industry. Many components of pellets are more digestible due to processing. And, pelleted feeds usually have a longer shelf life and are usually more economical based on the nutrients they provide compared to sweet feeds. Good-quality pelleted feeds are a must for horses with teeth in poor condition.

Supplements

Forage alone will rarely meet all nutrients needed by a horse. Good-quality forage can meet fiber, protein, and energy needs of mature horses at maintenance. Mineral and vitamin needs can be satisfied by using a good-quality mineral-vitamin supplement. In addition to mineral and vitamin supplementation, growing horses, gestating mares, and lactating broodmares need protein supplementation.

When forage is not of excellent quality, additional protein may also benefit working horses. The quality of protein is important. A higher quality protein supplement can increase growth and production. Crude protein level cannot always be used as an indicator of protein quality. For example, a 35% protein supplement may not necessarily provide better protein quality than a 33% protein supplement.

Balance is the key element in feeding horses. One of the most common errors in feeding horses, especially when using nutritional supplements, is overfeeding of some nutrients. To avoid potential nutrient toxicities, use one good-quality supplement rather than several from different feed manufacturers.

As mentioned earlier, forage needs are met by supplying good-quality pasture or hay. When it comes to concentrates, several options are available. Grain or grain by-products, along with a mineral-vitamin supplement (protein where needed) can be fed. This is probably the most economical concentrate feeding method. However, grain supply, storage, and mixing ability may not make this option feasible. Many horse owners prefer to use a bagged grain-based feed, which contains grain, fats, protein, minerals, and vitamins.

Not all feeds are created equal. For instance, protein levels can vary greatly, from 10% to 18%. The ingredient list can give an indication of feed quality. The collective feed term “roughage products” can be used for filler ingredients which do not contribute nutrients to the product. Filler ingredients simply “take up space.” Horse feeds with “fixed” formulas provide consistent quality compared to least-cost formulations that could provide varying nutrient amounts with each batch of feed produced.

One common practice observed is to replace or “cut” part of the grain-based feed with oats. Unless feeding directions specify, one should not combine oats with a grain-based feed. This practice upsets the balance of nutrients provided to the horse, namely protein, minerals, and vitamins.

Buy all feeds (hay, concentrate, or supplement) from a reputable supplier. Attention to quality ingredients is a must. Horse owners should know what they are buying and why it is needed. If one is in doubt as to a particular ingredient or nutrient, ask the feed supplier or a horse nutritionist. Never take for granted horses need everything touted on the market.