Cow-Calf Certification Practice Exam

Which trait is expected to have the greatest response to heterosis?

1. Mature height

2. Reproduction

3. Ribeye area

4. Weaning weight

The correct answer is: Reproduction

Heterosis, or hybrid vigor, refers to the phenomenon where crossbred individuals exhibit superior traits compared to their purebred parents. This enhanced performance often stems from increased genetic diversity and complementary traits from the different breeds involved in the crossbreeding. Reproduction, particularly in cattle, often demonstrates a strong response to heterosis. When cattle are crossbred, traits related to reproduction such as fertility rates, calf survival, and overall reproductive efficiency tend to show significant improvements. This is critical in a cow-calf operation where maximizing reproductive success can have a direct impact on the economic viability and productivity of the herd. Genetic variations between breeds can lead to more robust reproductive behaviors and efficiencies in crossbred animals, making this an area where heterosis is particularly beneficial. While other traits like weaning weight, ribeye area, and mature height can also show positive responses to heterosis, the reproductive traits are usually impacted more significantly. This is due to the high genetic complexity and the interaction of multiple genes contributing to successful reproduction, which can lead to more pronounced benefits in crossbred offspring.