Data/hora: 19/06/2024 17:41:16

Biblioteca(s): | Embrapa Gado de Corte.
Data corrente: | 11/01/2000
Data da última atualização: | 20/07/2011
Autoria: | MARIANTE, A. da S.
Afiliação: | ARTHUR DA SILVA MARIANTE, EMBRAPA. Centro Nacional de Pesquisa de Gado de Corte (Campo Grande, MS).
Título: | Growth and reproduction in nelore cattle in Brazil; genetic parameters and effects of environmental factors.
Ano de publicação: | 1978
Fonte/Imprenta: | Florida: University of Florida, 1978.
Páginas: | 130 f.
Idioma: | Inglês
Notas: | Tese (Doutorado) - University of Florida.
Conteúdo: | The objectives of this study were to determine the effects of various genetic and environmental factors on growth traits and reproductive performance of a herd of Nellore cattle in central Brazil. Weights at birth and at weaning (8 mo.), 12, 18, and 24 months of age collected over a 15-year period from 2,282 calves, were analyzed by least squares methods. Least squares means for these weights were 30.2+-.7, 187.5+-.0, 215.5+-.3, 282.6+-2.8, and 354.9+-4.0 kg. Year amd month of birth, sire and sex of calf affected (P<.01) weights at all ages. Age of dam had a significant (P<.10) effect on calf weight at 24 monts of age, and a highly significant effect on weights at the other ages. Heritability, estimated by paternal halfsib correlations, was .62+-.14, .12+-.14, 14+-.05, .13+-.05, and .18+-.06 for weight at birth, 8, 12, 18 and months, respectively. All genetic, phenotypic and environmental correlations between weights at different ages were positive. Correlations between weights tahen at ages closer together tended to be higher than those taken at more distant ages. Data from 335 calvings collected over an 11-year period were analyzed for age at first calving by least squares methods. The least squares mean for age at first calving was 40.3+-.7 months. Variables that significantly affected this traid were weight of the cow at birth, and at 8, 12, 18, and 24 months of age (P<.05), and sire of calf (P<.01). Heritability of age at first calving, estimated by paternal half-sib correlations, was .09+-12. Genetic, phenotypic and environmental correlations between birth weight and age at first calving were.65, .18, and.39, respectively. The genetic correlations between each of the other four weights and age at first calving were all positive; however, the correlations  decreased with increasing age. The phenotypic and environmental correlations between age at first calving and periodic  weights of the cow to 24 months of age all were negative. Least squares mean for calving interval was 400.2+- 10,4 days. Variables that significantly affected this trait were year of parturition (P<.01), month of parturition (P<.05), sex of calf (P<.05), sire of cow (P<.10), and weight gain of  previous calf to 3 months of age (P<.10). The heritability of calving interval was estimated by paternal halv-sib correlations and was. 06+- .05. The genetic correlations between calving interval and weights at birth, weaning and  at 12, 18, and 24 months of age were, respectively, .77+-.31, .81+-.30, .60+-.37, and .37+- .37. The phenotypic correlations were small and positive. All environmental correlations were positive, with exception of that between weaning weight and calving interval. Genetic, phenotypic, and environmental correlations between age at firts calving and calving interval were, respectively, .44, .02, and -.09.
Palavras-Chave: | Growth trait.
Thesagro: | Crescimento; Gado Nelore; Pecuária; Reprodução Animal; Zootecnia.
Thesaurus Nal: | Brazil; cattle breeding; reproduction; reproductive performance.
Categoria do assunto: | L Ciência Animal e Produtos de Origem Animal
Registro original: | Embrapa Gado de Corte (CNPGC)
Exemplares: | CNPGC - (6957-1) - ADD - TS - PP - T181/78 - MAR - T181/78 - DIS