Breed and heterotic effects for mature weight in beef cattle
By Anne Zinn
Cow mature weight affects the costs and efficiency of a breeding operation and has increased considerably over the past 30 years. Cow mature weight is influenced by genetics and the environment, which means producers need tools to incorporate cow mature weight in their selection of cattle breeds and herd replacements. Currently, the USDA, ARS, U.S. Meat Animal Research Center publishes across-breed adjustment factors for 18 breeds on various traits using crossbred animals from its Germplasm Evaluation program; doing so allows producers to compare Expected Progeny Differences from animals of different breeds, but cow mature weight is not currently among the traits analyzed. A paper recently published in the Journal of Animal Science estimated the breed and heterotic effect for cow mature weight in 18 beef breeds using weight-age data on crossbred cows.
The results of the present study indicated that no universal recommendations can be offered regarding the favorability of using breeds with larger to smaller mature weight. Beef cattle in the US are managed across vastly different environmentals, therefore the optimal size for a mature breeding cow will vary based on the operation’s unique environment, management style, breeding objective, and resource availability. Based on the similarity in the estimates of some of the breed effects, there may exist a greater opportunity to change mature weight within breed selection as opposed to breed choice depending on the breeds being considered, but for most of the breeds considered in this study, opportunities to alter mature weight though breed complementarity appeared limited. The results of the present study can help improve the efficiency of breed choice, regardless of the producer’s end goal.