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

This Article Full Text 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 HighWire Citing Articles via Google Scholar Google Scholar Articles by Norberg, E. Articles by Madsen, P. Search for Related Content PubMed PubMed Citation Articles by Norberg, E. Articles by Madsen, P.

Genetic Parameters for Test-Day Electrical Conductivity of Milk for First-Lactation Cows from Random Regression Models

¹ Department of Animal Breeding and Genetics, Danish Institute of Agricultural Sciences, Research Center Foulum, P.O. Box 50, 8830 Tjele, Denmark
² Department of Animal Science, University of Tennessee, Knoxville 37996, USA
³ Department of Dairy Science, University of Wisconsin, Madison 53706, USA

Corresponding author: E. Norberg; e-mail: Elise.Norberg{at}agrsci.dk.

Electrical conductivity (EC) of milk has been introduced as an indicator trait for mastitis during the last few decades. The correlation of EC to mastitis, easy access to EC data, and the low cost of recording are properties that make EC a good indicator trait for mastitis. In this study, EC was measured daily during the lactation and available from 2101 first-lactation Holstein cows in 8 herds in the United States. Data were analyzed with an animal model that included herd-test-day, age at calving and days in milk (DIM) as fixed effects, and random additive genetic and permanent environmental effects. A repeatability model and 5 random regression (RR) models with increasing order of Legendre polynomials were used. The goodness of fit for the different models was evaluated based on several tests. Our results indicate that the best model was a RR model with a fourth-order Legendre polynomial for both additive genetic and permanent environmental effects. Heritability estimates obtained with this model were from 0.26 to 0.36. Due to the relatively high heritability obtained for EC of milk, EC might be a potential indicator trait to use in a breeding program designed to reduce the incidence of mastitis.

Key Words: dairy cattle • electrical conductivity • mastitis • random regression model

Abbreviation key: 2ln = twice the log restricted likelihood, AG = additive genetic, AIC = Akaike information criterion, BIC = Bayesian information criterion, EC = electrical conductivity, MSEP = mean square error of predictions, PE = permanent environment, COP = the correlation between observed and predicted value, RR = random regression

This article has been cited by other articles:

				A. Sandrucci, A. Tamburini, L. Bava, and M. Zucali Factors Affecting Milk Flow Traits in Dairy Cows: Results of a Field Study J Dairy Sci, March 1, 2007; 90(3): 1159 - 1167. [Abstract] [Full Text] [PDF]

				E. Norberg, G. W. Rogers, J. Odegard, J. B. Cooper, and P. Madsen Short Communication: Genetic Correlation Between Test-Day Electrical Conductivity of Milk and Mastitis J Dairy Sci, February 1, 2006; 89(2): 779 - 781. [Abstract] [Full Text] [PDF]