An?lise multivariada de caracter?sticas reprodutivas em f?meas e avalia??o da produ??o in vitro de embri?es na ra?a Sindi (Bos indicus)

• Ano de defesa: 2016
• Autor(a) principal: Mello, Raquel Rodrigues Costa
• Orientador(a): Mello, Marco Roberto Bourg de
• Banca de defesa: Rodrigues, Andr? Luis Rios, Serapi?o, Raquel Varella, Jacob, Julio Cesar Ferraz, Jesus, Vera L?cia Teixeira de
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal Rural do Rio de Janeiro
• Programa de Pós-Graduação: Programa de P?s-Gradua??o em Zootecnia
• Departamento: Instituto de Zootecnia
• País: Brasil
• Palavras-chave em Português: An?lise de agrupamento; efici?ncia reprodutiva; produ??o de leite
• Palavras-chave em Inglês: Cluster analysis; milk yield; reproductive efficiency
• Área do conhecimento CNPq: Produ??o Animal
• Link de acesso: https://tede.ufrrj.br/jspui/handle/jspui/1346

The aim of this study was to investigate the possibility to generate different productive groups in Sindhi breed through multivariate techniques, in order to give directions to genetic improvement programs in this breed. For this goal, performance data provided by the Brazilian Association of Zebu Breeders related to 560 Sindhi breed females from 28 different herds in Brazil, born in the period from 1987 to 2011, were used. The traits age at first calving, calving interval, reproductive efficiency, total milk yield and lactation period were analyzed, being submitted to the principal components and cluster analysis, with the aid of GENES? statistical program. By the principal components analysis, these five components were estimated, and the first three explained 90.79% of the data?s total variation. The traits considered most relevant to the discrimination of the data set, in decreasing order of importance, were: calving interval, lactation period, age at first calving, total milk yield, and reproductive efficiency. By cluster analysis, twelve different groups were generated from the pool of Sindhi herds analyzed, with a great homogeneity among females for the traits evaluated, and only few females generating separate groups. Four hundred and twenty-nine females were clustered in one group, representing 76.60% of the genotypes. This indicates that, although there are genotypes with large genetic diversity, more than two thirds of the animals are similar to the traits evaluated, showing a high degree of relationship between them. The traits for total milk yield showed 71.92% of the total variation, and age at first calving contributed with 23.06% of the variation, being the two most important traits for the variability of the data. Thus, there is evidence of divergence between the groups regarding total milk yield, indicating that this trait stands out in the differentiation of groups, and these groups could be benchmarks for the use of genetic improvement programs whose focus is the increase in milk yield. In conclusion, the multivariate procedures were effective to summarize the evaluated information and to discriminate the most important traits, providing better identification of the most appropriate females to certain herds or milk production systems. The analysis of the relative contribution was effective in identifying total milk yield and age at first calving as the most relevant traits for the differentiation of groups, and they can be useful targets for genetic improvement programs that focus on milk yield and reproductive precocity.