Cow or Heifer? Typically a female cow before she has had her first calf is referred to as a “heifer”. And once she has had her first calf she becomes a cow. BUT, dairy farmers often make the distinction between a mature cow and a first lactation heifer…still referring to these young cows who HAVE already had their first calf, as heifers too. Why is that? Well when it comes to first lactation heifers, they still have some growing to do. Heifers will have their first calf at about 2 years of age a