Any cud-chewing ungulate, including antelope, camels, cattle, deer, giraffes, goats, okapis, pronghorn, and sheep. Most ruminants have a four-chambered stomach, two-toed feet, and small or absent upper incisors. Camels and chevrotains have three-chambered stomachs. Ruminants eat quickly, storing masses of grass (grazers) or foliage (browsers) in the first stomach chamber, the rumen, where it softens. They later regurgitate the material, called cud, and chew it again to break down the undigestible cellulose. The chewed cud goes directly to the other chambers, where various microorganisms help in its digestion.