Contribuição do componente genético de touros da raça nelore avaliados pelo desempenho de suas progênies em teste de desempenho de touros jovens

• Ano de defesa: 2012
• Autor(a) principal: MAMEDE, Mariana Márcia Santos
• Orientador(a): MAGNABOSCO, Claudio de Ulhoa
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Goiás
• Programa de Pós-Graduação: Mestrado em Ciência Animal
• Departamento: Ciências Agrárias - Veterinaria
• País: BR
• Palavras-chave em Português: mérito genético; prova de ganho em peso; raça Nelore
• Palavras-chave em Inglês: genetic merit; evidence of weight gain; Nelore
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::PRODUCAO ANIMAL
• Link de acesso: http://repositorio.bc.ufg.br/tede/handle/tde/888

Performance testing of young bulls are instruments of great utility in breeding programs and is aimed to evaluate the ability of individual animals regarding weight gain,, earliness, yield and carcass finishing, providing support for selection based on individual information of each animal. The objective of this study was to understand and define the relationships between genetic and quantitative genetic merit of Nellore bulls evaluated and their progenies in Performance Testing of Young Bulls(PTYB). In the present study, we analyzed the characteristics of weight calculated at 210 (W210), 365 (W365) and 450 days of age (W450), pre-weaning and post-weaning average daily gain (PREDG and POSTDG), scrotal circumference at 365 and 450 days of age (SC365 and SC450), ribeye area (REA) and carcass finishing (FIN) that were measured during the Weight Gain Tests (WET). The analyzed data set came from the Nellore participants in the Performance Testing of Young Bulls, which includes weight gain on pasture tests, from integrated crop and livestock production, coordinated by Embrapa Rice and Beans and Embrapa Cerrados. For data statistical analysis, we used statistical procedures available on the Statistical Analysis System (SAS) application and for obtaining (co)variance estimates, we used the Derivative-Free Restricted Maximum Likelihood method (DFREML), using univariate animal models and the Multiple Trait Derivative Free Restricted Maximum Likelihood (MTDFREML) application. Estimates of heritability for all traits showed moderate to high magnitudes. For direct and maternal additive effects, the heritability estimates were 0.37 ± 0.13 and 0.32 ± 0.15 and 0.35 ± 0.12 and 0.36 ± 0.16, for W210 and PREDG, respectively. As for W365, W450, POSTDG, SC365, SC450, REA and FIN, the additive heritability estimates were 0.33 ± 0.12, 0.53 ± 0.14, 0.54 ± 0.13, 0.36 ± 0.12, 0.54 ± 0.13, 0.26 ± 0.13 and 0.28 ± 0.14, respectively. Therefore, these results indicate the possibility of improving these characteristics by the use of breeding animals with superior genotype. Over the years there has been a significant entry of new bulls in evidence of weight gain on pasture, resulting in marked variation in predictions of genetic breeding values. However, there was positive and growing relationship between genetic value of bulls and their progeny. Thus, the results show that the selection of the best bulls based on genetic evaluations was efficient in terms of genetic progress.