title: Genetic parameters of test-day milk yield in Guzerá cattle under tropical conditions.
abstract: The objective of this study was to estimate genetic parameters for test-day milk yield (TDMY) in Guzerá cows using random regression models. Additive and permanent environmental random effects were modeled by random regression on fourth- and fifth-order orthogonal Legendre polynomials, respectively. The residual variances were heterogeneous, with seven classes. Heritability estimates for TDMY ranged from 0.24 to 0.52, with higher heritabilities for yields during early lactation. Genetic correlations between TDMYs ranged from -0.03 to 0.95. The phenotypic and permanent environmental correlations were all positive, and the highest estimates were between adjacent TDMYs. The results suggest that TDMYs obtained with random regression models may be used as selection criteria for Guzerá cattle.
authors.affiliation: Centro de Pesquisas de Bovinos de Corte, Instituto de Zootecnia, Sertãozinho, SP, Brasil.
authors.forename: D A C
authors.initials: DA
authors.lastname: Cruz
authors.affiliation: Embrapa Gado de Leite, Juiz de Fora, MG, Brasil.
authors.forename: M G C D
authors.initials: MG
authors.lastname: Peixoto
authors.affiliation: Embrapa Gado de Leite, Juiz de Fora, MG, Brasil.
authors.forename: F A T
authors.initials: FA
authors.lastname: Bruneli
authors.affiliation: Grupo de Melhoramento Animal de Mato Grosso, Instituto de Ciências Agrárias e Tecnológicas, Universidade Federal de Mato Grosso, Rondonópolis, MT, Brasil.
authors.forename: A B
authors.initials: AB
authors.lastname: Bignardi
authors.affiliation: Centro de Pesquisas de Bovinos de Corte, Instituto de Zootecnia, Sertãozinho, SP, Brasil.
authors.forename: L
authors.initials: L
authors.lastname: El Faro
mesh_terms: D000818:Animals; D002417:Cattle; D056726:Genetic Association Studies; D007774:Lactation; D008892:Milk; D019655:Quantitative Trait, Heritable; D014329:Tropical Climate