Características morfológicas e de manejo e suas relações com a produção de leite em vacas da raça gir

• Ano de defesa: 2008
• Autor(a) principal: Lagrotta, Marcos Rodrigues
• Orientador(a): Euclydes, Ricardo Frederico
• Banca de defesa: Carneiro, Antônio Policarpo Souza , Silva, Carlos Henrique Osório , Carneiro, Paulo Luiz Souza
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Zootecnia
• Departamento: Genética e Melhoramento de Animais Domésticos; Nutrição e Alimentação Animal; Pastagens e Forragicul
• País: BR
• Palavras-chave em Português: Bovino Gir; Vacas; Melhoramento genético; Lactação; Produção de leite
• Palavras-chave em Inglês: Dairy cattle; Gir; Cows; Breeding; Lactation; Milk yield
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::GENETICA E MELHORAMENTO DOS ANIMAIS DOMESTICOS
• Link de acesso: http://locus.ufv.br/handle/123456789/5591

Heritability and genetic and phenotypic correlations estimates to morphologic, handling and milk yield traits were obtained by REML method, using data from Associação Brasileira de Criadores de Gado Gir Leiteiro (ABCGIL). The software REMLF90 was utilized for such objective. The morphologic and handling traits were analysed for a model that differ of the utilized to the milk yield. The fixed effects used in the model of morphologic and handling traits were: contemporary group of herd, year and season of classification (RAEC); classifier; lactation phase and animal age on evaluation. For the milk yield was included in the model the fixed effects of cow age at calving and the contemporary group RAEP, shaped by combination herd, year and season of calving. The animal model was adopted in both analyses, which consider the random effect of repeatability, due to the fact that it was used more than one information per trait. The estimates of the heritability varied of 0.03 to 0.54, being the majority their larger than 0.15. Teat length and rump height were the traits that presented the largest coefficients of heritability (0.44 and 0.54, respectively), and backside view of rear legs, rear udder width, and foot angle, the least (0.03; 0.04; and 0.09, respectively). On practice, the additive genetic variability of the majority of traits was sufficient in order to reach significative annual genetic gain with the selection process. Rear udder width, fore udder insertion, backside view of rear legs, and side view of rear legs were the traits that presented the largest genetics correlations with milk yield (0.53; - 0.50; 0.42; and 0.30, respectively). The genetic antagonism between milk yield and fore udder insertion, associated to moderate heritability and direct influence of this trait on productive life of the cow, suggest that on formation of the selection index for milk yield, special attention must be given to it. The phenotypic correlations among milk yield and morphologic and handling traits were, in many cases, lower than the correspondent genetic correlations. Among the morphologic traits, the most expressive phenotypic correlations involved only the traits related to cow size. Genetic correlations among some morphologic traits were high, enabling the exclusion of some traits of the linear classification program adopted for the Gir breed in Brazil.