EFEITO DA ESTRUTURA DOS DADOS SOBRE AS ESTIMATIVAS DE (CO)VARIÂNCIAS DE PESO À DESMAMA EM BOVINOS DE CORTE, USANDO DADOS SIMULADOS

• Autor(a) principal: FERREIRA, Jorge Luís
• Data de Publicação: 2009
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tde/1177
• topic: bovinos; covariância genética direta-maternal; estrutura populacional; simulação; habilidade maternal; proporção elos mãe-progênie; 1. Bovino 2. Bovino de corte - Desmama 3. Covariância genética 4. Bovino - Estrutura populacional 5. Bovino - Habilidade maternal 6. Bovino - Proporção elos mãe-progênie; bovine; direct-maternal genetic covariance; population structure; maternal ability; proportion of mother-progeny links; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::PRODUCAO ANIMAL

The objective was to evaluate the effects of the year (sample size, genealogy and data structure), mother-offspring link proportion (mother-offspring pairs, both with weaning weights), inclusion (M2) or not (M1) of the genetic direct-maternal covariance in the model, the direct-maternal correlation (C) magnitude and the direct and maternal genetic variance ratio (R) on the (co)variance estimates on weaning weight of beef cattle. The effects of the correlation (C) and variance ratio (R) were significant on the estimate of direct genetic variance ( ) (P<0,05, P<0,001, respectively), maternal genetic variance ( ) (P<0,001) and direct-maternal genetic covariance ( ) (P<0,001). The year influenced significantly (P<0,01) the estimates of and was not significant on and . The effect of the mother-offspring link proportion (E) was significant (P<0,0001) on the estimate of , , , and , being not significant on . In the model with zero direct-maternal covariance, and were underestimated when the direct-maternal correlation was negative, and overestimated when it was positive. Accurate and precise estimates of genetic variances and covariances of traits under maternal effect deserve detailed study and intensified, since these estimates may be influenced by the nature and composition of data, direct-maternal genetic correlation model used and applied. However, these facts may contribute to mistaken conclusions that are not referenced. These results are indicatives of the potential reliability and accuracy of the estimates on real data, although it is known that its magnitudes may differ, due to additional bias, like inherent errors of data gathering process and information flow from the herds.