Random regression models to estimate test-day milk yield genetic parameters Holstein cows in Southeastern Brazil


Autoria(s): BIGNARDI, Annaiza Braga; FARO, Lenira El; CARDOSO, Vera Lucia; MACHADO, Paulo Fernando; ALBUQUERQUE, Lucia Galvao de
Contribuinte(s)

UNIVERSIDADE DE SÃO PAULO

Data(s)

18/10/2012

18/10/2012

2009

Resumo

A total of 152,145 weekly test-day milk yield records from 7317 first lactations of Holstein cows distributed in 93 herds in southeastern Brazil were analyzed. Test-day milk yields were classified into 44 weekly classes of DIM. The contemporary groups were defined as herd-year-week of test-day. The model included direct additive genetic, permanent environmental and residual effects as random and fixed effects of contemporary group and age of cow at calving as covariable, linear and quadratic effects. Mean trends were modeled by a cubic regression on orthogonal polynomials of DIM. Additive genetic and permanent environmental random effects were estimated by random regression on orthogonal Legendre polynomials. Residual variances were modeled using third to seventh-order variance functions or a step function with 1, 6,13,17 and 44 variance classes. Results from Akaike`s and Schwarz`s Bayesian information criterion suggested that a model considering a 7th-order Legendre polynomial for additive effect, a 12th-order polynomial for permanent environment effect and a step function with 6 classes for residual variances, fitted best. However, a parsimonious model, with a 6th-order Legendre polynomial for additive effects and a 7th-order polynomial for permanent environmental effects, yielded very similar genetic parameter estimates. (C) 2008 Elsevier B.V. All rights reserved.

State of Sao Paulo Research Foundation (Fapesp)

National Council of Technological and Scientific Development (CNPq)

Identificador

LIVESTOCK SCIENCE, v.123, n.1, p.1-7, 2009

1871-1413

http://producao.usp.br/handle/BDPI/19296

10.1016/j.livsci.2008.09.021

http://dx.doi.org/10.1016/j.livsci.2008.09.021

Idioma(s)

eng

Publicador

ELSEVIER SCIENCE BV

Relação

Livestock Science

Direitos

restrictedAccess

Copyright ELSEVIER SCIENCE BV

Palavras-Chave #Covariance functions #Genetic parameters #Legendre polynomials #RESTRICTED MAXIMUM-LIKELIHOOD #COVARIANCE FUNCTIONS #FRIESIAN CATTLE #LACTATION #RECORDS #GROWTH #SELECTION #TRAITS #AGE #Agriculture, Dairy & Animal Science
Tipo

article

original article

publishedVersion