Beef cow producers consider many traits when selecting replacement heifers. Gene Schmitz, University of Missouri Extension livestock specialist, says producers should add the age of the heifer’s dam to the list.

Schmitz points to research from the University of Nebraska finding that as the age of dam increases, offspring performance increases until the dam reaches 7 to 8 years old; and then, offspring performance begins to decrease.

The University of Nebraska looked at how the age of the dam affected heifer and steer productivity. Here are a few findings from the Nebraska Beef Cattle Report:

• Heifer calves born from 2-year-old dams had lower birth weight, lower adjusted 205-day weaning weight, lower prebreeding body weight and lower body weight at pregnancy diagnosis. “These heifers tended to have a lower cycling rate compared to heifers from older dams, but no difference in pregnancy rates was observed in the first breeding season,” Schmitz says. “However, these heifers had lower pregnancy rates in the second breeding season.”

• Heifers born from cows 4 to 9 years old had more calves born in the first 21 days of the calving season, greater body weight and body condition score at calving, and greater body condition score when their first calf was weaned.

• Steer calves born from 2-year-old dams had lower birth weights and adjusted 205-day weaning weights. According to the report, these steers produced more marbled carcasses, but the carcasses were lighter and less than steers from older dams.

As the age of the dam increased, steers had heavier hot carcass weights and greater rib-eye area until the dam was 7 to 8 years old; then, offspring performance decreased.

The bottom line, Schmitz says, is that selecting replacement heifer prospects from cows 4 to 8 years of age will result in heifers that will conceive more calves in the first 21 days of the breeding season, and produce heavier calves at weaning. He adds the additional weight will carry through to steer carcass weight and heifer body weight and body condition score at calving, and to greater body condition score when their first calf is weaned.

Source: University of Missouri Extension