The effect of adding further traits in index selection

Area of Science:

• Animal Breeding and Genetics
• Quantitative Genetics

Background:

• Index selection is a key tool in animal breeding for genetic improvement.
• The inclusion of additional traits can influence the overall response.

Purpose of the Study:

• To evaluate the impact of incorporating additional traits into index selection on genetic and economic responses.
• To determine the conditions under which adding traits is most beneficial.

Main Methods:

• Simulated genetic and economic responses using true and estimated parameters.
• Analysis focused on 2-4 traits with varying parameter sets.
• Quantified extra responses as a percentage of the original response.

Main Results:

• Adding traits to index selection often yielded substantial extra genetic and economic responses.
• Traits with a high product of heritability and economic weight (ah2) contributed most significantly.
• Favorable correlations between traits reduced extra response, while unfavorable correlations increased it.
• Results with estimated parameters were more variable, with some cases showing reduced response.

Conclusions:

• The value of adding traits in index selection is highly variable and depends on trait heritability, economic weight, and genetic correlations.
• With accurate parameter estimates, more traits can be included without compromising genetic response.
• In cases of poor parameter estimates, limiting selection to traits with high ah2 values is recommended.