Relationship between somatic cell score and longevity of Holstein cows in Brazil using a piecewise Weibull proportional-hazard model

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dc.contributor.authorKern, Elisandra Lurdes [UNESP]
dc.contributor.authorCobuci, Jaime Araujo
dc.contributor.authorNeto, José Braccini
dc.contributor.authorDos Santos Daltro, Darlene
dc.contributor.institutionUniversidade Estadual Paulista (Unesp)
dc.contributor.institutionUniversidade Federal do Rio Grande do Sul-UFRGS
dc.date.accessioned2019-10-06T16:06:04Z
dc.date.available2019-10-06T16:06:04Z
dc.date.issued2019-01-01
dc.description.abstractThe objective of the present work was to evaluate the effect of somatic cell score on the longevity of Holstein cows raised all over Brazil, using a piecewise Weibull proportional-hazard model. The following two longevity traits were defined: True longevity, number of days from first calving to culling and functional longevity, approximated by correcting true longevity to within-herd-year production. Records on productive life of 131 330 cows were used. The model included the time-independent effect of age at first calving. The other effects were time-dependent, and included the following: Region by year of calving, variation in herd-size class, milk-production class by year of calving within herd, within-herd milk-production class by number of lactations, within-herd fat content, within-herd protein content, and somatic cell score (SCS). The overall mean of the somatic cell counts (SCC) was 322 000 cells/mL. The highest SCC mean was found between 130 to 290 days of lactation. The SCC mean decreased over the years. Cows from Region 5 (Rio Grande do Sul) showed higher SCC means. The risk of culling was slightly higher for functional longevity than for true longevity. The impact of longevity was high in cows from first to fourth lactation with a high SCS, with the risk of culling varying from 0.90 (true longevity: Second lactation and Class 2) to 1.2 (functional longevity: Fourth lactation and Class 5). Cows at the fifth lactation with a lower SCS had a higher risk of culling (1.4). Including the effect of SCS class by stage of lactation in the models was not beneficial. The decrease in SCS, especially from the first to fourth lactation, can be used for indirect selection to improve the longevity of Holstein cows in Brazil.en
dc.description.affiliationDepartamento de Ciências Exatas Faculdade de Ciências Agrárias e Veterinárias Universidade Estadual Paulista-FCAV/UNESP, Via de Acesso Professor Paulo Donato Castellane s/n
dc.description.affiliationUniversidade Federal do Rio Grande do Sul-UFRGS Departamento de Zootecnia, Avenida Bento Goncąlves,7712 Agronomia
dc.description.affiliationUnespDepartamento de Ciências Exatas Faculdade de Ciências Agrárias e Veterinárias Universidade Estadual Paulista-FCAV/UNESP, Via de Acesso Professor Paulo Donato Castellane s/n
dc.format.extent1546-1552
dc.identifierhttp://dx.doi.org/10.1071/AN18069
dc.identifier.citationAnimal Production Science, v. 59, n. 8, p. 1546-1552, 2019.
dc.identifier.doi10.1071/AN18069
dc.identifier.issn1836-5787
dc.identifier.issn1836-0939
dc.identifier.scopus2-s2.0-85056740093
dc.identifier.urihttp://hdl.handle.net/11449/188376
dc.language.isoeng
dc.relation.ispartofAnimal Production Science
dc.rights.accessRightsAcesso aberto
dc.sourceScopus
dc.subjectDairy cattle
dc.subjectFunctional longevity
dc.subjectRisk of culling
dc.subjectSurvival analysis
dc.titleRelationship between somatic cell score and longevity of Holstein cows in Brazil using a piecewise Weibull proportional-hazard modelen
dc.typeArtigo
unesp.author.orcid0000-0003-2278-8129[4]

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