How do cows produce milk?

A cow’s special four-chambered stomach breaks down grasses she eats into things that nourish her and produce milk. The first chamber softens chewed plant material, which the cow burps up and chews again several times. In the next chamber, microorganisms feed on the plant material, making energy and proteins. As the material moves through the other chambers and into the small intestine, nutrients and excess water are absorbed into the bloodstream and then circulate to the mammary gland in the udder. There, special cells combine the nutrients with sugars from the cow’s liver to create milk.

Cows, goats, and other ruminants are valued around the world for their ability to digest low-nutrient grass and use it to make nutritious milk and meat.