Being that horses are natural grazers, they require a diet made up of
primarily forage. While this may have been the natural grasses and herbs found in their environment, a stabled performance horse is usually fed a combination of hays to best meet the bulk of their energy requirement.

There are a variety of different types of hay available on the market that may be split into four major groups: cool-season grasses, warm-season grasses, grain hays and legumes. We will begin by doing an overview of these four general types of hays and go into depth on the nutritional and management differences of each hay species in the coming weeks.

Cool-season grasses are grasses that grow best between 50°F and 77°F such as timothy, orchard, and fescue grasses. These hays are typically grown and cured in cooler and drier parts of the continent, such as Oregon, Washington, Montana, and Canada. Esthetically, these grasses are more appealing to consumers since they tend to retain their green color during the drying process. The caution with these types of hays in general, though, is that they tend to be more affected by extreme temperatures or drought conditions, causing them to store higher amounts of nonstructural carbohydrates (NSC) than warm-season grasses. This also means, though, that cool-season grasses are generally a palatable hay choice for picky eaters due to the higher sugar content.

Warm-season grasses – like bermuda, bahia, and teft – grow best in
hot temperatures between 77°F and 95°F and are often grown in the southern portion of the continent. These are generally less attractive since they lose their color quite easily during drying and storage, though this is very little indication of the nutrition of the hay itself. Often times, the nutritional values of warm-season grasses are comparable to coolseason grasses depending on the maturity level and the soil quality of where the hays were grown. Generally, though, warm-season have 5-10% less the nutrient amounts as cool-season grasses. These types of hays, however, have more predictable NSC levels compared to coolseason grasses, making warm-season grass hays a better choice for easy keepers or horses prone to metabolic issues.

Grain hays are hays that are made up of the dried stands of grain plants with the grain portion still intact, such as wheat, oat, and barley. These grain hays may be found in either found by themselves or as a blend commonly referred to as “three-way.” As a group, these hays are low in protein compared to grass hay and legume hays, so they should be always be fed with alfalfa or a high quality fortified grain. These hays are usually quite palatable, making them ideal for horses recovering from poor condition with a lower risk of over feeding them, as can happen with legume hays.

The final type of hay is legume hay, which is most commonly alfalfa hay, and sometimes clover or perennial peanut hay. Legume hay is known for being a good source of high quality protein and calories. It does also have a high calcium to phosphorus ratio, which may have some implications for skeletal and joint health, particularly in growing horses. One of the most noticeable benefits of legume hay is that it often takes less hay by weight to feed a horse than the other types of hays mentioned. That being said, the high calcium amount in the hay has been linked to the formation of enteroliths, or giant stones of calcium and magnesium that form in the horse’s gut which can result in colic, an internal blockage or death. The benefits of legume hays are best harnessed when fed as a supplement to the bulk of a ration made up of grass hay or grain hay.