Failure to develop heifers that can stay productive in the herd is a costly mistake. To help achieve successful heifer development, it is important to adopt an optimal mindset, not a maximal one.
If every heifer was to breed, fallout would undoubtedly occur as young cows. Short productive life as a mother cow lends little opportunity to recover a large investment in heifer development. Thus, focusing on reducing inputs while achieving acceptable pregnancy rates should be the focus of a successful heifer development program.
Heifer genetics and development need to fit the production environment. Maintaining short breeding seasons and continually selecting replacements from the front end of the calving season can help aid in developing heifers that match your production environment. It is important to account for age and weight when determining target weights for breeding.
Most literature shows heifers should be developed to 65% of mature bodyweight, although some have had success at slightly lower percentages. For example, consider the following scenario. Heifer Ranch maintains mature cows that weigh 1,400 pounds, they calve on March 1, and their cows wean 45% of their bodyweight when the calf is 6 months old. This results in heifer calves that weigh 630 pounds at weaning (180 days old). If they are bred to calve on March 1 at 2 years old, then the weaned replacement needs to be fed to gain an additional 280 pounds over the next 268 days (1.04 average daily gain) to weigh 910 pounds at breeding. While we can debate optimal when it comes to these numbers and percentages, getting heifers to target weights should not be that difficult. I typically see more overdeveloped heifers than underdeveloped.
Gain patterns should be steady and avoid weight declines at breeding. A common challenge is substantial early weight gain due to creep feed or abundant milk production followed by a period of poor gains due to forage dormancy or harsh weather conditions. While heifers may achieve target weight, poor or declining patterns of gain can negatively impact pregnancy rates.
Some producers that are limit-feeding heifers should consider adding an ionophore to the diet. This practice has been shown to aid in increased average daily gain (ADG) and help heifers reach sexual maturity earlier on the same feed resources.
Pelvic area measurements and reproductive tract scores are key measures to be taken prior to breeding. They can aid in culling heifers that are not fit for breeding. I would not recommend implanting replacement heifers or purchasing implanted heifers for replacements. It is important to consult your veterinarian on necessary vaccinations and to administer these vaccinations at least 30 to 45 days prior to breeding. Always give proper mineral supplementation and make sure heifers have an individual identification to allow accurate recordkeeping.
