ruminant

ruminant, (suborder Ruminantia), any mammal of the suborder Ruminantia (order Artiodactyla), which includes the pronghorns, giraffes, okapis, deer, chevrotains, cattle, antelopes, sheep, and goats. Most ruminants have a four-chambered stomach and two-toed feet. The upper incisors are reduced or sometimes absent. Camels and chevrotains, however, have a three-chambered stomach and are often referred to as pseudoruminants.

Ruminants eat quickly. However, they are unable to digest grasses, foliage, and other types of plant material directly, for their bodies do not produce enzymes capable of breaking down cellulose. Digestion occurs sequentially in a multichambered stomach. In ruminants with a four-chambered stomach, ingested plant material is stored in the first chamber, called the rumen, where it softens. They later regurgitate this material, called cud, and chew it again to further break down its cellulose content, which is difficult to digest. The chewed cud goes directly to the other chambers of the stomach (the reticulum, omasum, and abomasum), where it is further digested with the aid of various essential microorganisms that live in the stomach. The pseudoruminant digestive process is very similar, also involving regurgitation and cud chewing, though the stomach is divided into three chambers.