Estimativas de parâmetros genéticos e fenotípicos e análise de componentes principais para características de crescimento na raça Canchim
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Data
2000-12-01
Autores
Mascioli, Arthur dos Santos [UNESP]
El Faro, Lenira [UNESP]
Alencar, Maurício Mello de
Fries, Luiz Alberto
Barbosa, Pedro Franklin
Título da Revista
ISSN da Revista
Título de Volume
Editor
Sociedade Brasileira de Zootecnia
Resumo
Os objetivos deste trabalho foram obter estimativas de herdabilidade e de correlações genéticas, fenotípicas e de ambiente, para os ganhos diários de peso do nascimento à desmama (GND), da desmama aos 12 meses (GDA), dos 12 aos 18 meses (GASA) e dos 18 aos 24 meses (GSADA) de idade, e estimar componentes principais para essas características de crescimento na raça Canchim. Os dados foram analisados pelo método dos quadrados mínimos. As estimativas de herdabilidade foram iguais a 0,39±0,07 (GND), 0,20±0,04 (GDA), 0,20±0,05 (GASA) e 0,13±0,05 (GSADA). As correlações genéticas de GND com GASA e de GDA com GASA foram moderadas e positivas, indicando associação genética favorável entre essas características. As correlações genéticas entre os ganhos de peso e os seus pesos adjacentes foram normalmente altas e positivas. Para os pesos, o primeiro componente principal explicou 74% da variação total e é um índice das características estudadas, cuja importância elevou-se de acordo com a idade do animal. O segundo componente explicou 14% da variação total e diferenciou animais com maiores pesos da desmama aos 18 meses de idade com aqueles de maiores pesos aos 24 meses de idade, ou seja, caracterizando animais com maior ou menor precocidade de crescimento e taxa de maturação precoce versus tardia. Para os ganhos de peso, o primeiro componente explicou 44% da variação total e contrastou animais de maiores GDA e GSADA com animais de maiores GASA, ou seja, o ganho ocorrido nas épocas desfavoráveis com ganho durante a época favorável.
The objectives of this study were to obtain estimates of heritability and genetic, phenotypic and environmental correlations for average daily gains from birth to weaning (DGBW), from weaning to 12 months (DGW12), from 12 to 18 months (DG1218) and from 18 to 24 months (DG1824) of age, and to estimate the principal components for these growth traits in Canchim cattle. The data were analyzed by the least square method. The heritability estimates were 0.39± 0.07 (DGBW), 0.12±0.04 (DGW12), 0.20±0.05 (DG1218) and 0.13±0.05 (DG1824). The genetic correlations between DGBW and DG1218, and DGW12 and DG1218 were moderated and positive, indicating favorable genetic association among these traits. The genetic correlations among body weight gains and adjacent body weights were, in general, high and positive. For body weights, the first principal component explained 74% of total variation, and it is an index of the studied traits, and the importance of each one increased as the animal aged. The second component explained 14% of the variation, and contrasts heavier animals at weaning and at 18 months with heavier animals at 24 months old, characterizing animals with higher or less precocity and precocious and late maturation rate. For body weight gains the first component explained 44% of the total variation, and contrasts animals with higher DGW12 and DG1824 with animals with higher DG1218 or, in other words, contrasts the gains obtained during the less favorable season of the year (from weaning to one year of age and 18 to 24 months of age) with the gains obtained during the most favorable season of the year (from12 to 24 months).
The objectives of this study were to obtain estimates of heritability and genetic, phenotypic and environmental correlations for average daily gains from birth to weaning (DGBW), from weaning to 12 months (DGW12), from 12 to 18 months (DG1218) and from 18 to 24 months (DG1824) of age, and to estimate the principal components for these growth traits in Canchim cattle. The data were analyzed by the least square method. The heritability estimates were 0.39± 0.07 (DGBW), 0.12±0.04 (DGW12), 0.20±0.05 (DG1218) and 0.13±0.05 (DG1824). The genetic correlations between DGBW and DG1218, and DGW12 and DG1218 were moderated and positive, indicating favorable genetic association among these traits. The genetic correlations among body weight gains and adjacent body weights were, in general, high and positive. For body weights, the first principal component explained 74% of total variation, and it is an index of the studied traits, and the importance of each one increased as the animal aged. The second component explained 14% of the variation, and contrasts heavier animals at weaning and at 18 months with heavier animals at 24 months old, characterizing animals with higher or less precocity and precocious and late maturation rate. For body weight gains the first component explained 44% of the total variation, and contrasts animals with higher DGW12 and DG1824 with animals with higher DG1218 or, in other words, contrasts the gains obtained during the less favorable season of the year (from weaning to one year of age and 18 to 24 months of age) with the gains obtained during the most favorable season of the year (from12 to 24 months).
Descrição
Palavras-chave
componentes principais, ganhos de peso, parâmetros genéticos, pesos, genetic parameters, principal components, weights, weight gains
Como citar
Revista Brasileira de Zootecnia. Sociedade Brasileira de Zootecnia, v. 29, n. 6, p. 1654-1660, 2000.