HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Cunningham, E. P. Articles by Henderson, C. R. Search for Related Content PubMed Articles by Cunningham, E. P. Articles by Henderson, C. R.

Repeatability of Weaning Traits in Beef Cattle¹

Cornell University, Ithaca, New York

Abstract

The repeatability of average daily gain from birth to weaning (ADG) and type score at weaning (TS) has been estimated from a population of 4,838 weaning records of the Hereford and Angus breeds. The records were first adjusted for sex, age-of-dam and year differences. The assumptions involved in the use of the regression estimator of repeatability were examined, and this estimator was used to compute repeatability from all available pairs of records made by cows aged 10 years or less.

The values obtained agree with most estimates in the literature. The adjacency effect which is evident indicates that early records are a poor basis for prediction of performance more than 2 years removed. An adjacent record may be predicted with reasonable accuracy for ADG (repeatability=0.48) and less well for TS (repeatability=0.28). The variance of the corrected records for ADG decreased slightly with increasing age of dam. This may indicate more genetic homogeneity at older ages due to selection on earlier records.

¹ Based in part on a thesis submitted by the senior author to the Graduate School, Cornell University, in partial fulfillment of the requirements for the Ph.D. degree.

² Present address: Animal Breeding and Genetics Department, The Agricultural Institute, Castleknock, Co. Dublin, Ireland.