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) Interpretive Summary 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 Carlén, E. Articles by Strandberg, E. Search for Related Content PubMed PubMed Citation Articles by Carlén, E. Articles by Strandberg, E.

Comparison Between Linear Models and Survival Analysis for Genetic Evaluation of Clinical Mastitis in Dairy Cattle

Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, PO Box 7023, SE-750 07 Uppsala, Sweden

Corresponding author: E. Carlén; e-mail: Emma.Carlen{at}hgen.slu.se.

Clinical mastitis was analyzed with mixed linear models (LM) and survival analysis (SA) using data from the first 3 lactations of >200,000 Swedish Holstein cows having their first calving between 1995 and 2000. The model for both methods included fixed effects of year-month and age at calving, fixed regressions of proportions of heterosis and North American Holstein genes, and random effects of herd-year at calving and sire. For the LM, clinical mastitis was defined as a binary trait measured from 10 d before to 150 d after calving. For the SA, clinical mastitis was defined either as the time period from 10 d before calving to the day of first treatment or culling because of mastitis (uncensored record) or from 10 d before to the day of next calving, culling for reasons other than mastitis, movement to a new herd, or to lactation d 240 (censored record). The heritability estimates from SA (0.03 to 0.04) were higher than those obtained with the LM (0.01 to 0.03). Consequently, the accuracies of estimated transmitting abilities were also higher for the trait analyzed with SA. The difference between estimates from the 2 methods was greater for later lactations. This study reveals the potential of analyzing clinical mastitis data with SA.

Key Words: dairy cattle • clinical mastitis • linear model • survival analysis

Abbreviation key: LM = linear model, MAST = mastitis (0/1), PNA = proportion of North American Holstein genes, SA = survival analysis, TFM = time to first mastitis or censoring

This article has been cited by other articles:

				M. A. Perez-Cabal, G. de los Campos, A. I. Vazquez, D. Gianola, G. J. M. Rosa, K. A. Weigel, and R. Alenda Genetic evaluation of susceptibility to clinical mastitis in Spanish Holstein cows J Dairy Sci, July 1, 2009; 92(7): 3472 - 3480. [Abstract] [Full Text] [PDF]

				M. Rodrigues-Motta, D. Gianola, B. Heringstad, G. J. M. Rosa, and Y. M. Chang A Zero-Inflated Poisson Model for Genetic Analysis of the Number of Mastitis Cases in Norwegian Red Cows J Dairy Sci, November 1, 2007; 90(11): 5306 - 5315. [Abstract] [Full Text] [PDF]

				P. Bijma, W. M. Muir, E. D. Ellen, J. B. Wolf, and J. A. M. Van Arendonk Multilevel Selection 2: Estimating the Genetic Parameters Determining Inheritance and Response to Selection Genetics, January 1, 2007; 175(1): 289 - 299. [Abstract] [Full Text] [PDF]

				E. Carlen, U. Emanuelson, and E. Strandberg Genetic evaluation of mastitis in dairy cattle using linear models, threshold models, and survival analysis: a simulation study. J Dairy Sci, October 1, 2006; 89(10): 4049 - 4057. [Abstract] [Full Text] [PDF]

				A. Sewalem, F. Miglior, G. J. Kistemaker, and B. J. Van Doormaal Analysis of the relationship between somatic cell score and functional longevity in canadian dairy cattle. J Dairy Sci, September 1, 2006; 89(9): 3609 - 3614. [Abstract] [Full Text] [PDF]