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No. of bitstreams: 2 license_rdf: 22974 bytes, checksum: 99c771d9f0b9c46790009b9874d49253 (MD5) luiza_rodrigues_alves_abreu.pdf: 1513134 bytes, checksum: 72f00ac39b70f10a1e7718494968d97a (MD5) Previous issue date: 2014 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Objetivou-se com este estudo estimar as (co)vari?ncias e as associa??es gen?ticas para as caracter?sticas de pesos corporais, per?metro escrotal e os escores de avalia??o visual em bovinos da ra?a Guzer?. Foram utilizados dados de animais nascidos entre os anos de 1960 e 2013 de cinco estados brasileiros, registrados na ABCZ (Associa??o Brasileira de Criadores de Zebu). As caracter?sticas avaliadas foram: peso corporal ao nascimento (PN), pesos corporais aos 120, 205, 365, 450 e 550 dias de idade (P120, P205, P365, P450 e P550) e per?metros escrotais PE205, PE365, PE450 e PE550, al?m dos escores de avalia??o visual da conforma??o corporal (E ? estrutura corporal, P ? precocidade, M ? musculosidade, U ? umbigo, R ? ra?a, A ? aprumos e S - sexualidade). Os componentes de (co)vari?ncias foram estimados por modelo animal, uni e bi caracter?stica usando a infer?ncia bayesiana e assumindo modelo linear para os dados com distribui??o cont?nua e modelo limiar para as caracter?sticas com distribui??o discreta. As m?dias a posteriori para a herdabilidade direta, obtidas por an?lises unicaracter?sticas, foram: 0,38 (PN); 0,45 (P120), 0,41 (P205), 0,39 (P365), 0,40 (P450), 0,43 (P550), 0,15 (PE205), 0,62 (PE365), 0,32 (PE450), 0,60 (PE550), 0,33 (E), 0,30 (P), 0,32 (M), 0,38 (U), 0,34 (R), 0,39 (A) e 0,46 (S). As tend?ncias gen?ticas e fenot?picas indicam que houve evolu??o nos valores gen?ticos e fenot?picos dos animais ao longo dos anos. As correla??es gen?ticas estimadas entre peso corporal ? desmama (P205), peso corporal ajustado aos 450 dias de idade (P450), estrutura corporal (E), precocidade (P) e musculosidade (M) e as demais caracter?sticas foram positivas variando de m?dia a alta magnitude. Os resultados sugeriram que sele??o com base em pesos corporais ? desmama e aos 450 dias de idade, e escores visuais de estrutura corporal, precocidade e musculosidade resultaria como resposta direta ou correlacionada ? sele??o, em animais mais pesados em todas as idades, com maiores per?metros escrotais e com incremento nos escores visuais. / Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Zootecnia, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2014. / ABSTRACT The objective was to estimate the (co) variance and genetic associations for characteristics such as body weights, scrotal circumference, and visual appraisal scores in Guzerat cattle. Data of animals born between 1960 and 2013 in five Brazilian states, registered in the ABCZ (Brazilian Association of Zebu Breeders) were utilized. Evaluated characteristics were: body weight at birth (BWB); body weight at 120, 205, 365, 450, and 550 days of age (BW120, BW205, BW365, BW450, and BW550); scrotal circumference (SC) at day 205, 365, 450, and 550; and visual scores of body conformation (E - body structure, P - precocity, M - muscularity, U - umbilicus, R - breed, A - angulation and S - sexuality). The (co) variances were estimated by animal model, uni- and bi-characteristic using the Bayesian inference and assuming a linear model to the data with continuous distribution and threshold model for characteristics with discrete distribution. The a posteriori average for direct heritability obtained by univariate analysis were: 0.38 (BWB); 0.45 (BW120), 0.41 (BW205), 0.39 (BW365), 0.40 (BW450), 0.43 (BW550), 0.15 (SC205), 0.62 (SC365), 0.32 (SC450), 0.60 (SC550), 0.33 (E) 0.30 (P), 0.32 (M), 0.38 (U), 0.34 (R) 0.39 (A) and 0.46 (S). The genetic and phenotypic trends indicate an evolution in genetic and phenotypic values ??of animals over the years. Genetic correlation estimates between body weight at weaning (BW205), adjusted body weight at 450 days of age (BW450), body structure (E), precocity (P) and muscularity (M) and other characteristics were positive, ranging from average to high magnitude. The results suggested that selection based on body weight at weaning and 450 days of age, and visual scores of body structure, precocity and muscularity would result in direct response or correlated with selection in heavier animals at all ages, with greater SC and improved visual scores.