Hay is a fodder digested efficiently by farm livestock except for which animal listed?

Hay is a grass, a legume or other herbaceous plant that has been cut and dried to be stored for use as animal fodder, particularly for large grazing animals raised as livestock. Included as livestock are cattle, horses, donkeys, goats, and sheep. While pigs are omnivores, which means that they consume both plants and animals, they are foraging animals, primary eating leaves, roots, fruits, flowers. They may also be fed hay, but they do not digest it as efficiently.

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 not feasible due to weather (such as during the winter), or when lush pasture by itself would be too rich for the health of the animal. It is also fed when an animal is unable to access pasture. For example, the animal is being kept in a stable or barn.

Oat, barley, and wheat plant materials are occasionally cut green and made into hay for animal fodder.