The rumen, also known as a paunch, forms the larger part of the reticulorumen, which's 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's the reticulum, which's fully continuous with the rumen, but differs from it with regard to the texture of its lining. Brief anatomy The reticulorumen's composed of several muscular sacs, the cranial sac, ventral sac, ventral blindsac… (More on Rumen)