Comparison of selection methods at the same level of inbreeding

Area of Science:

• Animal Genetics and Breeding
• Quantitative Genetics
• Livestock Improvement

Background:

• Accurate selection is crucial for genetic gain in animal populations.
• Best Linear Unbiased Prediction (BLUP) uses relatedness information to enhance selection accuracy.
• Standard comparisons often maintain equal numbers tested and parental structures, leading to varied inbreeding levels.

Purpose of the Study:

• To investigate the impact of inbreeding on the comparison of selection methods, specifically BLUP versus phenotype selection.
• To determine if BLUP remains optimal when inbreeding is a controlled factor.
• To re-evaluate current animal breeding selection theory and practices.

Main Methods:

• Stochastic simulation was employed to model different selection strategies.
• Comparisons were made under two conditions: unrestricted inbreeding and a fixed, equal level of inbreeding across methods.
• Genetic response and inbreeding accumulation were quantified for each method.

Main Results:

• BLUP, by incorporating family information, inherently increases relatedness and inbreeding.
• When compared at the same inbreeding level, the genetic response differences between BLUP and phenotype selection diminish significantly.
• Phenotype selection can achieve higher genetic responses than BLUP under low to moderate, controlled inbreeding scenarios.

Conclusions:

• The assumption that BLUP is universally optimal for genetic gain is challenged, especially when inbreeding is restricted.
• Increased genetic response from BLUP often comes at the cost of higher inbreeding.
• A revision of selection methodology and optimization principles in animal breeding is warranted.