Cow

Cows are passive mobs which have brown skin with white spots. They are the only source of leather, raw beef, and milk. They are 1.6875 blocks tall, 0.625 blocks wide, and 1.5 blocks long.

Behavior
Cows roam in the Overworld, usually in herds of 4 to 10. They tend to walk around slow and aimlessly, mooing, but they will flee and jump wildly if attacked. Cows make no attempt to stay out of water. Cows will follow the player when holding wheat, which is used for Breeding. A cow can be milked by right clicking the cow with an empty bucket. A cow may be milked an unlimited number of times.

Breeding
Breeding cows with wheat will create a calf. The parent cows have a delay of 5 minutes until they can breed again. Parent cows will follow the calf until it is fully grown.

Calves will move faster and take 20 minutes to fully grow. They do not drop anything when killed. They can be milked, however.

It is possible to herd cows along with any other animal if you simply walk by a cow while holding wheat. The cow will follow you wherever you go. You can do this to lead animals into fenced areas for easy breeding.

Farming
Creating a colony of cows in an enclosed area and breeding them is a way to ensure that the player can get an unlimited supply of steak, milk and leather.

History
Cows were introduced in Alpha 1.0.8. When killed, they dropped only leather, and could be milked.

In Alpha 1.0.14, horns were added to cows' heads.

In Beta 1.8, as part of the first AI update, cows flee and jump wildly if attacked.

In 12w07a, cows were given a new AI system.

In Pocket Edition 3.0, cows were added.

Trivia

 * Cows in the PC Gamer Demo of Minecraft are branded with a 'PCG' logo on their side.
 * In SMP, clicking anywhere on the cow with a bucket will fill it with milk, but only at the maximum distance at which you can use the bucket.
 * Because of the lack of hierarchy in every box model, the horns of the cow are sometimes misplaced. Jeb is planning to fix this.
 * All cows in Minecraft both give milk and are capable of breeding with each other; there are no distinct sexes.

Bugs
Sometimes cows have a ghost entity in zero gravity and teleport back to their real spot.
 * If a cow is clicked with a bucket of milk it will revert to a newborn. (In multiplayer.)