Hay is grass, legumes, or other herbaceous plants that have been cut, dried, and stored for use as animal fodder, particularly for grazing animals such as cattle, horses, goats, and sheep. Hay is also fed to smaller animals such as rabbits and guinea pigs. Pigs may be fed hay, but they do not digest it as efficiently as more fully herbivorous animals.
Hay can be used as animal fodder when or where there is not enough pasture or rangeland on which to graze an animal, when grazing is unavailable due to weather (such as during the winter) or when lush pasture by itself is too rich for the health of the animal. It is also fed during times when an animal is unable to access pasture, such as when animals are kept in a stable or barn.
Commonly used plants for hay include mixtures of grasses such as ryegrass (Lolium species), timothy, brome, fescue, Bermuda grass, orchard grass, and other species, depending on region. Hay may also include legumes, such as alfalfa (lucerne) and clovers (red, white and subterranean). Legumes in hay are ideally cut pre-bloom. Other pasture forbs are also sometimes a part of the mix, though these plants are not necessarily desired as certain forbs are toxic to some animals.