Focus on heifer size for breedingU.S. dairy producers continue to focus on calving heifers at an earlier age, but as with any goal, there’s still room for improvement.

According to the 2007 National Animal Health Monitoring System dairy survey, the average age at first calving in the U.S. dairy herd is 25.2 months. This is down slightly from 25.4 months in 2002 and six months better than the average age of 25.8 months in 1996.

Research shows time and again that calving heifers into the herd between 22 and 24 months of age provides multiple benefits to the dairy, including:

  • Generating income sooner
  • Producing greater lifetime milk yield to maximize profits
  • Increasing the asset turnover ratio and financial efficiency of a dairy, because fewer replacements are needed to meet internal replacement needs2
  • Generating greater economic returns. In a California study, heifers had the largest economic return when calving between 23 and 24.5 months of age.3

To achieve the goal of earlier calving, producers must manage heifers to reach breeding size sooner.

Although age at breeding and calving are vitally important factors, the driver behind earlier calving is getting the animal to breeding size (height and weight) in a timely fashion.

The onset of puberty is not age-related, but size- and development-related. Puberty depends on a heifer’s plane of nutrition and average daily gain. Puberty, therefore, may be delayed or accelerated based on how heifers are fed and managed. Plane of nutrition or variation in feeding programs, along with levels of specific nutrients like protein and energy, can accelerate or decrease growth rates.

Read more on the Dairy Cattle Reproductive Council’s recommendations for heifer development and breeding here.