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 Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Alrawi, A. A. Articles by Laben, R. C. Search for Related Content PubMed PubMed Citation Articles by Alrawi, A. A. Articles by Laben, R. C.

Genetic Analysis of California Mastitis Test Records I. Coded Tests

Department of Animal Science, University of California, Davis 95616

ABSTRACT

A sample of 15,965 Holstein lactation records having California Mastitis Test scores for at least the first 9 mo of standard Dairy Herd Improvement production testing were studied for the effects of sire, parity, and year and month of calving. California Mastitis Test readings of "negative" or "trace" were coded normal while readings of "1", "2", or "3" were coded elevated. The frequency of elevated tests increased as parity increased. Effect of year of calving and a trend toward higher percentages of elevated coded test scores was significant. There was no distinct trend in elevated coded test score with month of calving. Sire effect on the incidence of elevation in the coded score was important. Heritability of first and second lactation monthly coded California Mastitis Test scores from a paternal half-sister analysis within herd, year, and season, for sires with at least 25 daughters ranged from .11 ± .04 to .48 ± .07. Genetic correlations between the third test and following tests of first and second lactations ranged from .25 ± .15 to .58 ± .18.

¹ Animal Production Department, College of Agriculture, Aba-Ghraib, Iraq.