How economic weights translate into genetic and phenotypic progress, and vice versa

Area of Science:

• Quantitative genetics
• Animal breeding
• Genomic selection

Background:

• Genomic breeding programs aim for genetic progress in complex, multi-trait objectives.
• Selection indices combine estimated breeding values for various trait complexes.

Purpose of the Study:

• Develop a framework to calculate expected genetic and phenotypic progress for complex breeding objectives.
• Analyze the sensitivity of breeding programs to changes in economic weights.
• Propose a method to derive covariance structure of estimation errors for breeding values.

Main Methods:

• Applied classical selection index theory and quantitative genetic models.
• Developed a novel approach to derive covariance structure from observed correlations of estimated breeding values.
• Defined and calculated 'realized economic weights' based on observed genetic trend.

Main Results:

• Observed genetic progress composition closely matched predictions, improving when estimation error covariance was included.
• Expected phenotypic trend significantly deviated from genetic trend due to varying heritabilities.
• Realized economic weights substantially differed from predefined weights, sometimes with reversed signs.

Conclusions:

• The proposed framework accurately predicts genetic progress in complex breeding objectives.
• Significant discrepancies between genetic and phenotypic trends highlight the impact of heritability.
• The study provides tools for developing more rational and accepted breeding objectives in animal breeding programs.