Modelos de dimensão infinita para estimação de parâmetros genéticos da produção de leite de búfalos da raça Murrah

• Autor(a) principal: Breda, Fernanda Cristina
• Data de Publicação: 2008
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1272
• topic: Regressão aleatória; Valores genéticos; Variâncias residuais; Random regression; Genetic values; Residual variance; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::GENETICA E MELHORAMENTO DOS ANIMAIS DOMESTICOS

Genetic parameters for first lactation test-day milk yields of buffaloes Murrah breed were estimated using random regression models, using restricted maximum likelihood and Bayesian methods. A total of 17,935 test-day milk records of 1,433 buffaloes were used to describe the changes that happen in the variances along lactation curve. The models included fixed effects of contemporary group, milking number and age of buffaloe as covariable. Firstly were analyzed twenty seven random regression models using Wilmink, Ali & Schaeffer function or Legendre orthogonal polynomial to fit additive genetic and permanent environmental effects. The models were compared by Akaike s information criterion (AIC), Bayesian information criterion (BIC), Log likelihood function, information-theoretic measure of model complexity (ICOMP), percentage relative reduction of complexity (PRRC) and weighted residual variance (VRP). In second part of this work, were tested 12 models, varying the orders of the orthogonal polynomial (third, fourth, fifth, sixth and seventh orders) for the additive and permanent environmental effects. The models were compared by residual mean square errors, variances components, heritabilities, correlations, eigenvalues and eigenfunctions estimates. The results indicated that random regression models were adequate to describe the genetic variation for test-day milk yield, except for the beginning and at the end of the lactation, and the following random regression models can be recommended to fit test- day milk yields of buffaloes in evaluation genetic programs: model using Ali and Schaeffer function with homogeneous residuals variances (AS_HO) and models using fourth and sixth order for additive genetic and permanent environmental effect , respectively, with six residuals variances classes (PL466 ).