Cows are normally milked 2 times per day, however some high producing herds are milked 3 times per day. Normally cows are milked at about 6 am in the morning and again at about 5 pm in the evening. Milking time takes about 5 minutes per cow but depends on the type of machine and the amount of milk the cow is producing. Most dairies have enough machines to milk 20 to 40 cows at  one time, reducing the amount of time the cows wait to be milked. Milking machines mimic the action of a young calf by creating a pulsating vacuum around the teat, which causes the milk to be released from the udder.