Do cows have to be pregnant to produce milk?
Not necessarily. Female cows of course START to produce milk while they are pregnant, just like any other mammal, including humans. Cows are milked even when their calves are weaned to continue the milking process. A cow can actively produce milk for as little as 3 months and as long as 3 years. The longer the cow goes without a break to build up the mammary glands, however, the less productive the milk supply will be.
