The stomach of a ruminant has four chambers.

1. The grass enters the rumen and the reticulum, where symbiotic microorganisms digest the cellulose.

2. The ruminant periodically regurgitates and rechews the cud, to further break down the fibers.

3. The cud is reswallowed, and moves to the omasum, where water is removed.

4. The cud finally passes to the abomasum for final digestion by the ruminant's own enzymes.