Genotype × environment interaction in individual performance and progeny tests in beef cattle

Area of Science:

• Animal Genetics
• Quantitative Genetics
• Beef Cattle Breeding

Background:

• Understanding genotype × environment interaction (G×E) is crucial for effective breeding programs in beef cattle.
• Nellore young bulls were evaluated for performance traits under different management systems (pasture vs. feedlot).

Purpose of the Study:

• To evaluate G×E interaction for final weight (FW), average daily gain (ADG), and scrotal circumference (SC) in Nellore beef cattle.
• To determine the impact of selection intensity in different environments on genetic gains.

Main Methods:

• Analysis of genetic parameters (heritability and genetic correlations) for FW, ADG, and SC in pasture and feedlot environments.
• Comparison of direct and correlated responses to selection under varying selection intensities.

Main Results:

• Heritability estimates varied between environments, with higher heritability for SC in feedlots (0.65) compared to pasture (0.53).
• Genetic correlations between environments were moderate to high, suggesting some shared genetic basis but also potential for G×E.
• Selection in feedlots yielded greater direct responses for FW and ADG when selection intensity was equal across environments.

Conclusions:

• Traits with lower heritability, such as ADG, are more sensitive to G×E interactions.
• Selection intensity significantly influences the outcomes of G×E interaction studies and breeding program effectiveness.
• Accurate assessment of G×E is vital to avoid misinterpretations and optimize genetic improvement in beef cattle.