the digestive system of a sheep has evolved to
Sheep 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. When sheep graze, vegetation is chewed into a mass called a bolus, which is then passed into the rumen, via the reticulum. The rumen is a 19- to 38-liter (5 to 10 gal) organ in which feed is fermented.[32] The fermenting organisms include bacteria, fungi, and protozoa.[33] (Other important rumen organisms include some archaea, which produce methane from carbon dioxide.[34]) The bolus is periodically regurgitated back to the mouth as cud for additional chewing and salivation.[32] After fermentation in the rumen, feed passes into the reticulum and the omasum; special feeds such as grains may bypass the rumen altogether. After the first three chambers, food moves into the abomasum for final digestion before processing by the intestines. The abomasum is the only one of the four chambers analogous to the human stomach, and is sometimes called the "true stomach".[35]