||Dairy farming is a complicated business because the farmer has to keep the cows on a schedule in order to maintain a steady supply of milk year round. A cow must be at least two years old before she is bred, and she is able to make milk only after she has given birth to a calf. The milk that the cow produces is food for her young. However, even after the calf is older and weaned, the mother continues to produce extra milk that humans can use for food.
Cows have similar gestation or pregnancy periods as humans. A female cow is pregnant for nine months, and the farmer stops milking her two months before her next calf is due so that she will stop producing milk and become "dry." She starts making milk again once her calf is born. Therefore, you can probably imagine how a dairy farmer must keep track of every cow in the herd and maintain a breeding schedule so that there is enough milk being produced for us to drink throughout the whole year.