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Genetic parameters of somatic cell count in dairy sheep considering the type of mammary pathogen effect
Author(s) -
Gonzalo C.,
Ariznabarreta A.,
Othmane M. H.,
Carriedo J. A.,
De La Fuente L. F.,
San Primitivo F.
Publication year - 2003
Publication title -
journal of animal breeding and genetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.689
H-Index - 51
eISSN - 1439-0388
pISSN - 0931-2668
DOI - 10.1046/j.1439-0388.2003.00394.x
Subject(s) - udder , heritability , biology , somatic cell count , flock , repeatability , genetic correlation , mastitis , genetic variation , zoology , somatic cell , analysis of variance , veterinary medicine , genetics , statistics , lactation , ecology , mathematics , medicine , microbiology and biotechnology , pregnancy , ice calving , gene
Summary Genetic parameters for somatic cell count (SCC) from half‐udder milk were estimated from 4692 monthly test‐day records from each half‐udder of 1337 Churra ewes belonging to seven dairy flocks. The total number of observations was 9348. Variance and co‐variance genetic components were estimated using a multitrait repeatability animal model. The log SCC of the right and left half‐udders were considered as two dependant variables in the model. The species of organisms causing intramammary infection were identified and included or not in the analysis as a fixed effect. The inclusion of the mammary pathogen fixed effect did not influence the estimation of heritability. However, the proportions of permanent environmental variance and repeatability were significantly reduced in comparison with the model that did not include this effect. On the other hand, the genetic correlation between SCC in milk from left and right glands was close to unity, and no differences were detected between both glands for all genetic estimates. The importance of the mammary pathogen factor was evaluated in comparison with the other fixed effects studied, which in relation were of little importance.