A:   There are data comparing beef females calving for the first time at 24 months of age verses 36 months of age. Most producers breed beef females to have their first calf at 24 months of age. The data suggests that breeding heifers to calve for their first time at 24 months produce .8 more calves over their lifetime compared to breeding them to calve at 36 months of age. Following is the web location of a research trial conducted at the Meat Animal Research Center comparing breeding to calf for the first time at 24 or 36 months of age. There data suggest that there is a decrease of 6 to 8 percent in cost per unit of output if beef females are bred to calve for their first time at 24 compared to 36 months of age. There are Oklahoma data that indicates that cows calved for the first time at 24 months of age wean 330 more pounds of calf over their lifetime compared to those calved first at 36 months of age.

Calving at 36 months use to be not that uncommon. Producers reasoned that calving beef females at 36 months of age decreased input cost, especially feed, labor costs, and decreased calving difficulity at their first calving because they were older.

Some producers that have both a spring and fall calving herd sometimes generate replacement heifers for the fall herd from the spring herd and replacements for the spring herd are generated from the fall herd. So females at their first calving are 30 months of age. I would guess that input costs per unit of output would be between females calves at 24 and 36 months of age.