The fibrous bulk of a horse’s diet is referred to as roughage. This can be fed fresh, as grass, or it may be preserved, like hay and silage. A horse’s digestive system, unlike that of humans, can obtain nutrients from the plant fiber because it has a very long colon that has evolved to properly facilitate this task. Cellulose, the main component of roughage, is digested in the colon by bacteria. The bacteria digest the cellulose and return soluble carbohydrates, fatty acids, and amino acids as byproducts of digestion. Colic may result if a horse does not eat enough bulky food to keep the colon fairly full.

Grass is the most natural form of roughage for a horse. The horse has to bite off each mouthful, so it is eaten slowly, aiding in digestion. Grass changes its character and nutritional value through the seasons. It is most nutritious in the early summer, just before flowering occurs. In spring, the grass has higher water content; in the winter, some grass may be as dry as hay.

Hay is dried grass. Meadow hay is made from permanent pasture and contains a variety of grasses and herbs, while seed hay is made from specially grown grass. Good hay is crisp, smells sweet, and is greenish brown in color. Bad hay will contain more stalk than leaf. It may be yellowish brown because the pigment has been bleached out. If the hay has been cured or stored in poor conditions, a white mold may be present. It is important to feed good-quality hay. Some hay may have little nutritional value; some may contain a high concentration of fungal spores which can trigger respiratory ailments. Be sure not to feed hay containing poisonous plants since they can be fatal, even when dried.

There are also other fibrous foods that can take the place of hay. Some include:

• Vacuum-packed grass–A damp and softer hay; it also has twice the nutritional value. The grass is vacuum-packed just after harvest and a cold fermentation occurs within the bag.

• Alfalfa–A good mineral source that can be fed as hay or chopped and dried. Its leaves are larger than those of other grasses, which help to make it more nutritious than the best meadow hay. It is very rich, so it should be fed in less quantity.

• Silage–Normally fed to cattle rather than horses. Do not allow a horse to eat from a trough with cattle. Overeating can cause laminitis or colic.

• Chaff–Straw chopped into tiny pieces. Bacteria in the colon can readily digest chaff. Its length will not cause impactions of the bowel, as longer straw may have a tendency to do. It can be mixed in with concentrate food, has little nutritional value, but adds necessary bulk.

• Chaff and molasses–Most horses enjoy the taste of something sweet. If your horse needs additional bulk in its diet, molasses can be added to chaff to make it more appealing. The molasses also helps to bind the chaff together, slightly increasing the nutritional value and making it less dusty.

• Hydroponic grass–Grown artificially on trays that contain no soil. The horse is presented with a mat made up of intertwined seeds, roots, and shoots. Grass grown in this manner has very little fibrous content, but has a good nutritional value compared to most types of dried roughage.

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