How does a four-chambered stomach help many ruminants digest plants?

It is a common misconception that ruminants have four separate stomachs; rather, they possess a single stomach divided into four specialized compartments: the rumen, reticulum, omasum, and abomasum.1

This structure allows ruminants to digest fibrous plant material, such as cellulose, which their bodies cannot break down on their own. The process functions as follows:21

• Fermentation: Ingested food enters the rumen, which acts as a fermentation vat where microorganisms break down cellulose into nutrients like volatile fatty acids.13
• Regurgitation: Ruminants regurgitate the partially digested material, known as cud, to chew it again. This further breaks down the plant fibers and mixes them with ruminal fluid.23
• Processing: The reticulum assists in mixing, while the omasum absorbs water and nutrients.1
• Final Digestion: The abomasum, or true stomach, uses acid and enzymes to digest proteins, preparing the material for absorption in the small intestine.1