Dairy cattle

To maintain lactation, a dairy cow must be bred and produce calves. Depending on market conditions, the cow may be bred with a ``dairy bull'' or a ``beef bull.'' Female calves (heifers) with dairy breeding may be kept as replacement cows for the dairy herd. If a replacement cow turns out to be a substandard producer of milk, she then goes to market and can be slaughtered for beef. Male calves can either be used later as a breeding bull or sold and used for veal or beef. Dairy farmers usually begin breeding or artificially inseminating heifers around 13 months of age. A cow's gestation period is approximately nine months. Newborn calves are removed from their mothers quickly, usually within three days, as the mother/calf bond intensifies over time and delayed separation can cause extreme stress on both cow and calf.

Question: do cows only produce milk when they have babies
Answer: yes