Reaction norm for yearling weight in beef cattle using single-step genomic evaluation

Area of Science:

• Animal Genetics
• Quantitative Genetics
• Genomic Selection

Background:

• Diverse environments necessitate models accounting for genotype by environment interaction (G × E) in animal breeding.
• Selecting superior sires across varied environments requires understanding G × E for traits like yearling weight (YW).

Purpose of the Study:

• To evaluate G × E for YW in Nellore cattle using reaction norm models.
• To compare pedigree-based and genomic-based reaction norm models.
• To identify genomic regions associated with environmental gradients for YW.

Main Methods:

• Utilized reaction norm models with pedigree and genomic relationships (single-step genomic BLUP).
• Analyzed 67,996 YW records and genetic parameters using average information restricted maximum likelihood.
• Identified genomic regions using additive genetic variances explained by SNP windows.

Main Results:

• Both traditional and genomic models confirmed G × E for YW.
• Genomic information improved prediction of future animal performance by 7.9% on average.
• Identified specific genomic regions on BTA5 and BTA14 associated with environmental gradients.

Conclusions:

• Genotype by environment interaction is present for YW in Nellore cattle.
• Single-step genomic BLUP in reaction norm models enhances prediction accuracy across environments.
• Genomic insights aid in selecting animals for specific environmental conditions.