Breeding should occur when the heifer reaches puberty. Puberty is a function of breed, age, and weight. Most heifers will reach puberty and be bred by 12 to 14 months of age and will be between 55% and 65% of their mature weight when they first begin to exhibit estrous cycles. Higher growth heifers and heifers that have a breed composition that is a high percentage bos indicus (Brahman) are later maturing and are older at puberty.

There are, in some cases, beef females that will cycle at less than a year of age and become pregnant. This is called precocious puberty. These females may be still nursing their dams. This doesn't happen often, but can happen. This is too young for a beef female to become pregnant because at calving these females tend to have difficult births as the birth canal is not fully developed.