SHEEP: (Ovis aries) are quadrupedal, ruminant mammals typically kept as livestock. Like all ruminants, sheep are members of the order Artiodactyla, the even-toed ungulates. Although the name sheep applies to many species in the genus Ovis, in everyday usage it almost always refers to Ovis aries. Numbering a little over one billion, domestic sheep are also the most numerous species of sheep. A male sheep is called aram and a female sheep is called a ewe. The domestic sheep is a multi-purpose animal, and the more than 200 breeds now in existence were created to serve these diverse purposesSome sources give a count of a thousand or more breeds, but these numbers cannot be verified, according to some sources. Sheep are exclusively herbivorous mammals. Most breeds prefer to graze on grass and other short roughage, avoiding the taller woody parts of plants that goats readily consume.[31] Both sheep and goats use their lips and tongues to select parts of the plant that are easier to digest or higher in nutrition.  Sheep, however, graze well in monoculture pastures where most goats fare poorly.[31] Like all ruminants, sheep have a complex digestive system composed of four chambers, allowing them to break down cellulose from stems, leaves, and seed hulls into simpler carbohydrates.