“When heifers get pregnant is extremely important to profitability,” says Rick Funston, a University of Nebraska-Lincoln (UNL) beef reproduction physiologist at the West Central Research and Extension Center in North Platte. “A cow that calves in the first cycle during her lifetime will produce the equivalent of two more calves on the same resources. That’s powerful.”

There are two parts to this equation: when heifers calved the first time and when in the calving season the heifer was born.

First, research from the U.S. Meat Animal Research Center affirms the fact that heifers calving early in their first calving season have increased longevity and wean more pounds of calf, compared with heifers calving later with their first calf.

Next, Funston compiled research involving 1,019 heifers (Figure 1). Those born in the first 21 days of the calving season were heavier at weaning and breeding. Significantly more heifers cycled in the first 21 days with a higher conception rate. Significantly more heifers (81%) born in the first 21 days went on to calve themselves in the first 21days, compared to heifers born in the second cycle (69%) and third cycle (65%).

time of calving affects heifer progeny

Funston believes producers can get a long way toward achieving this with the heifers they select, and by paying attention to how much weight heifers gain and when.

Eliminate the usual suspects

At this summer’s annual meeting of the Beef Improvement Federation (BIF), Funston offered selection criteria espoused by Jim Gosey, UNL Extension beef specialist emeritus.

Assuming that open cows are culled, Gosey suggested getting rid of daughters from cows that:

  • Calve late (42 days or more in the breeding season)
  • Need help calving
  • Fail to wean a calf
  • Wean a lighter calf
  • Have big teats and need help with calves nursing
  • Have an attitude problem

Gosey also suggested that heifers from the older cows in the herd deserved extra consideration as keepers. Though that runs counter to the notion that the youngest cows should be the most genetically advanced, Funston explains the older cows have proven their ability to survive longest in your ranch environment.

“Keep the heifers that are born early. They’re heavier at weaning, they’re better cycling, better breeding, and have higher pregnancy rates and more calves born in the first 21 days,” Funston emphasizes.