Puzzle 11: How Now Brown Cow

Cows are ruminants, and have four stomachs, each of which performs a special function.

1. Rumen - When grass is eaten it goes to the rumen where it is softened before going to the second stomach.
2. Reticulum - The grass becomes softer and is formed into wads called 'cuds'. The cuds go back to the mouth where the cow chews it some more.
3. Omasum - Once the cud has been chewed it is swallowed into the third stomach, and is broken down more.
4. Abomasum - The grass is digested in the fourth stomach, before passing to the intestine.

Just like many other animals, the cow then extracts nutrients from the digested food in the intestine.

How does a cow turn grass into milk?