Heifer – a cow that has not borne a calf, or has borne only one calf. In North America, a typical farm has about 100 milk cows and as many young female stock called heifers. The heifers are raised as replacement cows.
Goldilock region is the space which is neither too hot nor too cold and has conditions which are a must for life. So the Goldilock zone is a habitable zone.