Estimativas de parâmetros genéticos para características de crescimento e de carcaça em ovinos de corte
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Data
2011-07-29
Autores
Ono, Rafael Keith [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Objetivo do presente estudo foi estimar componentes de (co)variância e parâmetros genéticos para as características de crescimento: Peso ao nascer (PN), Peso ao desmame (PD), Ganho de peso pré-desmama (GDPRÉ) e Ganho de peso pós-desmama (GDPÓS) e de carcaça: Área de olho de lombo (AOL) e Espessura de gordura subcutânea (EGS) para uma raça materna composta. Os dados utilizados foram oriundos de uma fazenda pertencente ao programa de melhoramento genético de ovino (OviGol®), coletados entre os anos de 2008 e 2011. Os efeitos ambientais considerados nos modelos foram determinados a partir de análise de variância, pela metodologia dos quadrados mínimos, considerando apenas efeitos significativos (p<0,01). Os componentes de (co)variâncias e os parâmetros genéticos para as características foram estimados pelo método da máxima verossimilhança restrita (REML), sob modelo animal, utilizando o programa REMLF90. Avaliaram-se dois modelos em análises unicaracterísticas pelo teste da razão de verossimilhança (LRT), sendo escolhido o modelo mais completo, o qual incluía como efeitos aleatórios o ambiente permanente materno e o genético aditivo. As herdabilidades diretas estimadas em análise multi-característica, sob modelo animal, foram: 0,26; 0,20; 0,23; 0,15; 0,18 e 0,10, para PN, GDPRÉ, PD, GDPÓS, AOL e EGS respectivamente. As correlações genéticas variaram de baixa a alta magnitude, sendo a mais alta entre GDPRÉ e PD (0,99) e a mais baixa entre PN e GDPÓS (0,02). Os resultados indicam que há variação genética para PN, PD e GDPRÉ, com possibilidade de seleção dentro da população
The aim of this study was to estimate the (co)variance components and genetic parameters for growth: Birth Weight (BW), Weaning Weight (WW), average daily gain pre-weaning (ADGpre) and average daily gain post-weaning (ADGpos) and carcass: Eye Muscle Area (EMA) and Fat Depth (FD) for a composite maternal breed. The data used were from a farm belonging to the breeding program for sheep (OviGol®), collected between 2008 and 2011. The environmental effects considered in models were determined from analysis of variance by least squares method, considering only significant effects (p<0.01). The components of (co)variance and genetic parameters were estimated by restricted maximum likelihood (REML), under the animal model, obtained by the REMLF90 program. Two models were tested, differentiated only by random effects in single-trait analysis of the likelihood ratio test (LRT), whichever is the more complete model, which included as random maternal permanent environmental and additive genetic. The direct heritability, analysis in multi-trait and in an animal model, was 0.26, 0.20, 0.23, 0.15, 0.18 and 0.10, for BW, ADGpre, WW, ADGpos, EMA and FT respectively. Genetic correlations ranged from low to high values, being the highest among ADGpre and WW (0.99) and lowest between BW and ADGpos (0.02). The study indicates that there is genetic variation for PN, GDPRÉ and PD, with scope for selection within population
The aim of this study was to estimate the (co)variance components and genetic parameters for growth: Birth Weight (BW), Weaning Weight (WW), average daily gain pre-weaning (ADGpre) and average daily gain post-weaning (ADGpos) and carcass: Eye Muscle Area (EMA) and Fat Depth (FD) for a composite maternal breed. The data used were from a farm belonging to the breeding program for sheep (OviGol®), collected between 2008 and 2011. The environmental effects considered in models were determined from analysis of variance by least squares method, considering only significant effects (p<0.01). The components of (co)variance and genetic parameters were estimated by restricted maximum likelihood (REML), under the animal model, obtained by the REMLF90 program. Two models were tested, differentiated only by random effects in single-trait analysis of the likelihood ratio test (LRT), whichever is the more complete model, which included as random maternal permanent environmental and additive genetic. The direct heritability, analysis in multi-trait and in an animal model, was 0.26, 0.20, 0.23, 0.15, 0.18 and 0.10, for BW, ADGpre, WW, ADGpos, EMA and FT respectively. Genetic correlations ranged from low to high values, being the highest among ADGpre and WW (0.99) and lowest between BW and ADGpos (0.02). The study indicates that there is genetic variation for PN, GDPRÉ and PD, with scope for selection within population
Descrição
Palavras-chave
Ovino - Melhoramento genético, Ovinos de corte - Carcaça, Sheep - Growth, Sheep - Carcass
Como citar
ONO, Rafael Keith. Estimativas de parâmetros genéticos para características de crescimento e de carcaça em ovinos de corte. 2011. xv, 50 f. Dissertação (mestrado) - Universidade Estadual Paulista, Faculdade de Ciências Agrárias e Veterinárias, 2011.