RUMEN

WHAT

• The rumen, also known as a paunch, forms the larger part of the reticulorumen, which is the first chamber in the alimentary canal of ruminant animals. It serves as the primary site for microbial fermentation of ingested feed. The smaller part of the reticulorumen is the reticulum, which is fully continuous with the rumen, but differs from it with regard to the texture of its lining.

IT DOES

• Digested food (digesta) in the rumen is not uniform, but rather stratified into gas, liquid, and particles of different sizes, densities, and other physical characteristics. Additionally, digesta does not merely enter and exit the rumen without event, but it is subject to extensive mixing, and travels along complicated flow paths. Though they may seem trivial at first, these complicated stratification, mixing, and flow patterns of digesta are a key aspect of digestive activity in the ruminant and thus warrant detailed discussion.
• The rumen is composed of several muscular sacs, the cranial sac, ventral sac, ventral blindsac, and reticulum.