HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS

QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

Full Text of this Article PDF Version of this Article Similar articles found in: JDS Online Search PubMed for articles by: Wiggans, G. R. || Wright, J. R. Alert me when: new articles cite this article Download to Citation Manager

Type Trait (Co)Variance Components for Five Dairy Breeds

¹ Animal Improvement Programs Laboratory, Agricultural Research Service, USDA, Beltsville, MD 20705-2350
² Animal Science Unit, Gembloux Agricultural University, B-5030 Gembloux, Belgium and National Fund for Scientifique Research, B-1000 Brussels, Belgium

Corresponding author: G. R. Wiggans; e-mail: wiggans@aipl.arsusda.gov.

(Co)variance components were estimated for final score and 14 or 15 linear type traits for the Ayrshire, Brown Swiss, Guernsey, Jersey, and Milking Shorthorn breeds. Appraisals from 1995 or later were used. New estimates were calculated to accommodate changes in scoring of traits and because of a change from multiplicative to additive adjustment for age and lactation stage. The adjustment method was changed for better support of the adjustment for heterogeneous variance within iteration, which was implemented in 2002. The largest changes in heritability were an increase of 0.10 for rump angle for Milking Shorthorns and a decrease of 0.11 for udder depth for Jerseys. The new estimates of (co)variance components should provide improved accuracy of type evaluations, particularly for traits that have had variance changes over time.

Key Words: type trait ·variance component estimation