How Do We Improve Percent Calf Crop Weaned?
The percent calf-crop weaned is of paramount economic importance in a cow-calf operation. As a follow up to my most recent topic, this week we address selection, mating and management to improve reproductive efficiency. First, take a look at the following chart. It shows the inverse relationship between heritability and heterosis.
From a standpoint of genetics and animal breeding, reproductive traits are low in heritability (typically 10% - 20%) but show high levels of heterosis in response to crossbreeding. From a practical standpoint, this means if we are going to take advantage of heterosis in one part of our commercial cow-calf operation, take advantage of maternal heterosis in your cowherd. The crossbred cow has an advantage in “reproductive fitness.”
That being said, when selecting seedstock for a well-designed crossbreeding system, consider genetic values. Genetic change is cumulative and permanent. Selecting bulls with strong EPDs for reproductive traits will result in their daughters having high genetic potential for reproductive efficiency. Yes, these traits are low heritability; however, additive genetic merit pays long-term dividends. Each beef registry publishes a sire summary that includes several EPDs that fall under the “Maternal” heading. Applying selection pressure to EPDs such as Heifer Pregnancy, Maternal Calving Ease and Mature Weight or bio-economic indices like Stayability, Maternal Weaned Calf Value, Baldy Maternal Index or Brahman Influence Index enable you to genetically tailor your cowherd to fit your production environment and thereby maximize reproductive efficiency. This is by no means a complete listing of all the maternal EPDs that could be considered.
From a standpoint of management, herd health and proper nutrition are essential to maximize reproductive performance. A good working relationship with your veterinarian enables you to tailor a herd health plan best suited to your production environment and cow herd. When it comes to a proper vaccination program and parasite control an ounce of prevention is worth a pound of cure.
Past articles have stressed the importance of nutritional management and the critically important role it plays in reproductive efficiency. Cows and heifers that go into the calving season at a body condition score of 5.5 – 6.0 are optimum. This ensures they have the energy reserves to deal with the spike in nutritional requirements once lactation starts and have timely breed back. Optimum reproductive efficiency is getting ALL our cows to raise a calf to weaning in a 365 day window of time. That means the rebreeding interval needs to stay within 80-85 days of calving. Parasite control, a good vaccination program and proper nutrition all play a vital role in maintaining an optimum rebreeding interval and keeping cows bred.
