Milk Bucket

Milk is found only in Alpha mode. It is obtained from cows by using (i.e., right-clicking) a bucket on a cow.

A bucket of milk however currently serves no purpose, although it is speculated to be a food in a future update. Once milk is in a bucket the only way to remove it from the bucket is to dump the contents on to the ground. When dumped, Milk will not act as Water, but rather disappear. Every cow can be milked multiple times. Notch confirmed that if he wins he will add cake to the game, milk being one of the ingredients.