How does a cow’s digestive system help it process grass?

Contrary to the common misconception that cows have four separate stomachs, they possess a single stomach divided into four specialized compartments: the rumen, reticulum, omasum, and abomasum. This complex system allows them to digest fibrous plant material, such as grass, which contains cellulose that most animals cannot break down on their own.12

The process works as follows:

• Rumen and Reticulum: The rumen acts as a large fermentation vat where microorganisms break down tough cellulose. The reticulum works with the rumen to mix this material and catch foreign objects.13
• Chewing the Cud: To assist digestion, cows regurgitate partially digested food—known as cud—and re-chew it. This behavior allows them to quickly ingest large amounts of grass while grazing and break it down more thoroughly later.123
• Omasum: This chamber absorbs water and nutrients, concentrating the food before it moves to the final stage.1
• Abomasum: Often called the "true stomach," this compartment uses acid and enzymes to digest proteins, similar to the stomach in humans, preparing the material for absorption in the small intestine.1