title: Genotype × environment interactions in reproductive traits of Nellore cattle in northeastern Brazil.
abstract: We evaluate genotype × environment (G × E) interactions for age at first calving (AFC) and calving interval (CI) of Nellore cattle in northeastern Brazil using four hierarchical reaction norm models (HRNMs). The best-fit model for the traits was the one step heteroscedastic hierarchical reaction norm model. Heritability was close to zero in the worst environments and increased as the environments improved (from 0.06 to 0.12 for AFC and from 0.01 to 0.03 for CI). The correlations between the intercept and the slope of the reaction norms for CI and AFC were from medium to high magnitude (0.75 ± 0.10 and 0.90 ± 0.04, respectively), indicating that animals with higher average breeding values had the greatest responses to the improvement of environmental conditions. The variation in heritability indicates different response to selection according to the environment in which the animals of the population are evaluated. The G × E was evident in bulls with more female offspring. In conclusion, our data demonstrate that selection for AFC in medium- and high-level environments leads to higher genetic gains.
authors.affiliation: Programa de Pós-Graduação em Zootecnia, Universidade Estadual do Sudoeste da Bahia, Praça Primavera, n°40, CEP: 45700-000, Itapetinga, BA, Brazil. diegopagung@yahoo.com.br.|, Avenida Pedro Alvares Cabral, Bairro Interlagos I, n° 558, CEP - 29903-042, Linhares, ES, Brazil. diegopagung@yahoo.com.br.
authors.forename: Diego Pagung
authors.initials: DP
authors.lastname: Ambrosini
authors.affiliation: Programa de Pós-Graduação em Zootecnia, Universidade Estadual do Sudoeste da Bahia, Praça Primavera, n°40, CEP: 45700-000, Itapetinga, BA, Brazil.
authors.forename: Carlos Henrique Mendes
authors.initials: CH
authors.lastname: Malhado
authors.affiliation: Universidade Federal do Ceará, Campus de Cariri. Av. Tenente Raimundo Rocha, s/n°, CEP 63040-360, Juazeiro do Norte, CE, Brazil.
authors.forename: Raimundo Martins
authors.initials: RM
authors.lastname: Filho
authors.affiliation: Empresa Brasileira de Pesquisa Agropecuária, Centro de Pesquisa de Pecuária dos Campos Sul-Brasileiros, BR 153, km 603, CEP 96401-970, Bagé, RS, Brazil.
authors.forename: Fernando Flores
authors.initials: FF
authors.lastname: Cardoso
authors.affiliation: Programa de Pós-Graduação em Zootecnia, Universidade Estadual do Sudoeste da Bahia, Praça Primavera, n°40, CEP: 45700-000, Itapetinga, BA, Brazil.
authors.forename: Paulo Luiz Souza
authors.initials: PL
authors.lastname: Carneiro
mesh_terms: D000818:Animals; D001938:Brazil; D001947:Breeding; D002417:Cattle / Q000235:genetics* / Q000254:growth & development; D004777:Environment; D005260:Female; D005838:Genotype; D008297:Male; D010641:Phenotype; D012098:Reproduction; D014329:Tropical Climate
keywords: Age at first calving; Beef cattle; Calving interval; Environmental sensitivity; Genetic evaluation; Reaction norms