Reaction norm model to describe environmental sensitivity across first lactation in dairy cattle under tropical conditions

dc.contributor.authorBignardi, Annaiza Braga
dc.contributor.authorEl Faro, Lenira
dc.contributor.authorPereira, Rodrigo Junqueira
dc.contributor.authorAyres, Denise Rocha
dc.contributor.authorMachado, Paulo Fernando
dc.contributor.authorAlbuquerque, Lucia Galvão de [UNESP]
dc.contributor.authorSantana, Mário Luiz
dc.contributor.institutionUniversidade Federal de Mato Grosso (UFMT)
dc.contributor.institutionInstituto de ZootecniaUniversidade de São Paulo (USP)
dc.contributor.institutionUniversidade Estadual Paulista (Unesp)
dc.description.abstractReaction norm models have been widely used to study genotype by environment interaction (G × E) in animal breeding. The objective of this study was to describe environmental sensitivity across first lactation in Brazilian Holstein cows using a reaction norm approach. A total of 50,168 individual monthly test day (TD) milk yields (10 test days) from 7476 complete first lactations of Holstein cattle were analyzed. The statistical models for all traits (10 TDs and for 305-day milk yield) included the fixed effects of contemporary group, age of cow (linear and quadratic effects), and days in milk (linear effect), except for 305-day milk yield. A hierarchical reaction norm model (HRNM) based on the unknown covariate was used. The present study showed the presence of G × E in milk yield across first lactation of Holstein cows. The variation in the heritability estimates implies differences in the response to selection depending on the environment where the animals of this population are evaluated. In the average environment, the heritabilities for all traits were rather similar, in range from 0.02 to 0.63. The scaling effect of G × E predominated throughout most of lactation. Particularly during the first 2 months of lactation, G × E caused reranking of breeding values. It is therefore important to include the environmental sensitivity of animals according to the phase of lactation in the genetic evaluations of Holstein cattle in tropical environments.en
dc.description.affiliationUniversidade Federal de Mato Grosso, Grupo de Melhoramento Animal de Mato Grosso, Instituto de Ciências Agrárias e Tecnológicas
dc.description.affiliationUniversidade de São Paulo, Departmento de Zootecnia
dc.description.affiliationUnespUniversidade Estadual Paulista, Departamento de Zootecnia, Faculdade de Ciências Agrárias e Veterinárias de Jaboticabal
dc.identifier.citationTropical Animal Health And Production, v. 47, n. 7, p. 1405-1410, 2015.
dc.relation.ispartofTropical Animal Health And Production
dc.rights.accessRightsAcesso restrito
dc.subjectEnvironment interactionen
dc.subjectTest dayen
dc.titleReaction norm model to describe environmental sensitivity across first lactation in dairy cattle under tropical conditionsen
unesp.campusUniversidade Estadual Paulista (Unesp), Faculdade de Ciências Agrárias e Veterinárias, Jaboticabalpt
unesp.departmentZootecnia - FCAVpt