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Measuring the effect of change in selection indices.

E P Cunningham¹, H Tauebert

¹Department of Genetics, Trinity College, Dublin 2, Ireland. epcnnghm@tcd.ie

Journal of Dairy Science

|November 20, 2009

Summary

This study redefines relative emphasis in dairy cattle genetic selection, proposing a new metric based on economic value to accurately reflect trait contributions and avoid overstating changes in selection goals.

Area of Science:

Animal Genetics
Quantitative Genetics
Dairy Cattle Breeding

Background:

Dairy cattle genetic selection has evolved from production traits to include health, fertility, and functionality.
Expanding selection goals involves incorporating additional measured phenotypic variates.
Current methods for defining the relative emphasis of traits in selection goals may be imprecise.

Purpose of the Study:

To propose a new, more accurate definition for the relative emphasis of target traits in genetic selection.
To introduce a parallel statistic for measuring the relative contribution of each recorded phenotypic variate.
To contrast the proposed measures with existing methods using United States Holstein data.

Main Methods:

Proposed a new definition of relative emphasis based on the percentage of total economic value of genetic gain attributable to a specific trait.

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Developed a parallel statistic to measure the relative contribution of each phenotypic variate.

Applied and contrasted these new measures with current methods using United States Holstein data.

Main Results:

Current definitions of relative emphasis in dairy cattle genetic selection may overstate the net effect of changes.
The proposed definition provides a more accurate measure of trait importance within selection goals.
The new parallel statistic offers a clearer understanding of the contribution of individual phenotypic variates.

Conclusions:

A revised definition of relative emphasis is crucial for accurately assessing genetic selection strategies in dairy cattle.
The proposed economic value-based approach offers a more precise method for evaluating trait contributions.
These new measures enhance the understanding and application of genetic selection for improved dairy cattle breeding.