Animal Science Department

 

Date of this Version

March 1971

Comments

Published in Journal of Dairy Science. Copyright © 1971 American Dairy Science Association. Used by permission.

Abstract

Phenotypic and genetic correlations were estimated between 48 type appraisal traits and first lactation milk production to determine the importance of appraisal traits in a breeding program from 5,024 records from the New York type appraisal program. Most phenotypic correlations among the type traits were near zero. Depth of udder was the appraisal trait having the highest correlation with first lactation milk (.27) and fat (.23). Multiple correlations of all appraisal traits with first lactation milk and fat were .44 and .40.

Correlations with lifetime variables were calculated from 2,068 records meeting time qualifications. Of the first lactation variables, milk yield had the highest correlation with lifetime milk (.34), and fat yield had the highest correlation with number of lactations (.21). All appraisal traits combined were as effective as production variables in predicting number of lactations.

Genetic correlations suggested that bulls that sire daughters with high production tend to sire daughters with weaker udder attachments. High genetic correlations between first lactation production and lifetime performance support the utility of selection on first lactation production.

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