A cow is a ruminant that has one stomach with four digestive compartments. These four compartments are the rumen, the reticulum, the omasum and the abomasum.
The rumen is the first and largest compartment, holding up to 50 gallons of digested feed. Fermentation of feed and fiber takes place in the rumen. It also contains billions of microbes or bacteria that aid in the digestion of substances, such as cellulose and hemicellulose.
The reticulum connects to the rumen. This compartment’s function is to capture and collect large feed particles for more rumination. The third compartment is the omasum, which contains many folds that act as filters and also extract water from the food.
The last compartment of a cow’s stomach is the abomasum. Here, enzymes break down the protein from feed into amino acids. From the abomasum, these nutrients travel into the bloodstream and the small intestine.