Characterization of the variable cow's age at last calving as a measurement of longevity by using the Kaplan-Meier estimator and the Cox model

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dc.contributor.authorCaetano, S. L. [UNESP]
dc.contributor.authorRosa, G. J M
dc.contributor.authorSavegnago, R. P. [UNESP]
dc.contributor.authorRamos, S. B. [UNESP]
dc.contributor.authorBezerra, L. A F
dc.contributor.authorLôbo, R. B.
dc.contributor.authorDe Paz, C. C P
dc.contributor.authorMunari, D. P. [UNESP]
dc.contributor.institutionUniversidade Estadual Paulista (Unesp)
dc.contributor.institutionUniversity of Wisconsin
dc.contributor.institutionUniversidade de São Paulo (USP)
dc.contributor.institutionANCP - Associação Nacional de Criadores e Pesquisadores
dc.contributor.institutionAgência Paulista de Tecnologia dos Agronegócios (APTA)
dc.date.accessioned2014-05-27T11:28:45Z
dc.date.available2014-05-27T11:28:45Z
dc.date.issued2013-04-01
dc.description.abstractIn most studies on beef cattle longevity, only the cows reaching a given number of calvings by a specific age are considered in the analyses. With the aim of evaluating all cows with productive life in herds, taking into consideration the different forms of management on each farm, it was proposed to measure cow longevity from age at last calving (ALC), that is, the most recent calving registered in the files. The objective was to characterize this trait in order to study the longevity of Nellore cattle, using the Kaplan-Meier estimators and the Cox model. The covariables and class effects considered in the models were age at first calving (AFC), year and season of birth of the cow and farm. The variable studied (ALC) was classified as presenting complete information (uncensored = 1) or incomplete information (censored = 0), using the criterion of the difference between the date of each cow's last calving and the date of the latest calving at each farm. If this difference was >36 months, the cow was considered to have failed. If not, this cow was censored, thus indicating that future calving remained possible for this cow. The records of 11 791 animals from 22 farms within the Nellore Breed Genetic Improvement Program ('Nellore Brazil') were used. In the estimation process using the Kaplan-Meier model, the variable of AFC was classified into three age groups. In individual analyses, the log-rank test and the Wilcoxon test in the Kaplan-Meier model showed that all covariables and class effects had significant effects (P < 0.05) on ALC. In the analysis considering all covariables and class effects, using the Wald test in the Cox model, only the season of birth of the cow was not significant for ALC (P > 0.05). This analysis indicated that each month added to AFC diminished the risk of the cow's failure in the herd by 2%. Nonetheless, this does not imply that animals with younger AFC had less profitability. Cows with greater numbers of calvings were more precocious than those with fewer calvings. Copyright © The Animal Consortium 2012.en
dc.description.affiliationDepartamento de Ciências Exatas Faculdade de Ciências Agrárias e Veterinárias (FCAV) Universidade Estadual Paulista (UNESP), CEP 14884-900, Jaboticabal, SP
dc.description.affiliationDepartment of Animal Sciences University of Wisconsin, Madison, WI 53706
dc.description.affiliationDepartamento de Genética Faculdade de Medicina de Ribeirão Preto Universidade de São Paulo, CEP 14049-900, Ribeirão Preto, SP
dc.description.affiliationANCP - Associação Nacional de Criadores e Pesquisadores, CEP 14020-230, Ribeirão Preto, SP
dc.description.affiliationAPTA - Agência Paulista de Tecnologia Dos Agronegócios, CEP 14001-970, Ribeirão Preto, SP
dc.description.affiliationUnespDepartamento de Ciências Exatas Faculdade de Ciências Agrárias e Veterinárias (FCAV) Universidade Estadual Paulista (UNESP), CEP 14884-900, Jaboticabal, SP
dc.format.extent540-546
dc.identifierhttp://dx.doi.org/10.1017/S1751731112001826
dc.identifier.citationAnimal, v. 7, n. 4, p. 540-546, 2013.
dc.identifier.doi10.1017/S1751731112001826
dc.identifier.file2-s2.0-84876897409.pdf
dc.identifier.issn1751-7311
dc.identifier.issn1751-732X
dc.identifier.lattes6064277731903249
dc.identifier.scopus2-s2.0-84876897409
dc.identifier.urihttp://hdl.handle.net/11449/74950
dc.identifier.wosWOS:000315413100002
dc.language.isoeng
dc.relation.ispartofAnimal
dc.relation.ispartofjcr1.870
dc.relation.ispartofsjr0,842
dc.rights.accessRightsAcesso restrito
dc.sourceScopus
dc.subjectbeef cattle
dc.subjectcow's age at calving
dc.subjectCox model
dc.subjectKaplan-Meier estimator
dc.subjectaging
dc.subjectanimal
dc.subjectbiological model
dc.subjectbirth
dc.subjectBrazil
dc.subjectcattle
dc.subjectfemale
dc.subjectKaplan Meier method
dc.subjectlongevity
dc.subjectphysiology
dc.subjectpregnancy
dc.subjectproportional hazards model
dc.subjectAging
dc.subjectAnimals
dc.subjectCattle
dc.subjectFemale
dc.subjectKaplan-Meier Estimate
dc.subjectLongevity
dc.subjectModels, Biological
dc.subjectParturition
dc.subjectPregnancy
dc.subjectProportional Hazards Models
dc.titleCharacterization of the variable cow's age at last calving as a measurement of longevity by using the Kaplan-Meier estimator and the Cox modelen
dc.typeArtigo
dcterms.licensehttp://journals.cambridge.org/action/displaySpecialPage?pageId=4676
unesp.author.lattes6064277731903249
unesp.campusUniversidade Estadual Paulista (Unesp), Faculdade de Ciências Agrárias e Veterinárias, Jaboticabalpt

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