Interação genótipo x ambiente na avaliação genética de búfalos

• Ano de defesa: 2007
• Autor(a) principal: Moita, Antonia Kécya França
• Orientador(a): Lopes, Paulo Sávio
• Banca de defesa: Tonhati, Humberto , Freitas, Ary Ferreira de
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Genética e Melhoramento
• Departamento: Genética animal; Genética molecular e de microrganismos; Genética quantitativa; Genética vegetal; Me
• País: BR
• Palavras-chave em Português: Búfalo; Melhoramento genético; Interação genótipo-ambiente; Genética animal
• Palavras-chave em Inglês: Buffaloes; Breeding; Genotype-environment interaction; Animal genetics
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::GENETICA E MELHORAMENTO DOS ANIMAIS DOMESTICOS
• Link de acesso: http://locus.ufv.br/handle/123456789/1420

Milk yield records of 754 Murrah buffaloes were used to evaluate the effect of sire x herd and sire x herd-year interactions and to verify the effects of heterogeneity of variance among herds on genetic evaluation. The (co)variance components were estimated by restricted maximum likelihood method using six models in single trait analyses, considering season and herd-year of birth as fixed effects and cow age as covariate (linear and quadratic effects). The following models were used: 1 additive; 2 repeatability; 3 additive with sire x herd interaction; 4 additive with sire x herd-year interaction; 5 repeatability with sire x herd interaction; and 6 repeatability with sire x herd-year interaction. An average of 1736.66 Kg of milk production was obtained. There were significant effects of the inclusion of permanent environment or sire x herd-year interaction on the additive model (P<0.06 and P<0.05, respectively), and sire x herd-year interaction on the repeatability model (P<0.05). The non-inclusion of permanent environment effect on the additive model inflated the estimates of additive genetic variance and heritability for milk yield. The sire x herd-year interaction showed more important than sire x herd interaction on genetic evaluation of buffaloes for milk yield. The models 1, 2, 4 and 6 were used in two-trait analysis, considering two classes of phenotypic standard deviation for milk production as different traits. A single trait analysis was also accomplished, without phenotypic standard deviation classes, including sire x herd-year interaction (model 6). In two-trait analyses, higher estimates of additive genetic variance components were obtained in high than in low standard deviation class. In the model 6 (without classes) the most part of animals selected for milk yield were from high standard deviation herds. Despite the increase of additive and residual variances in the high standard deviation class, their heritability estimates were lower, except for model 2 that showed high estimate in high standard deviation class. The stratification of herds in high and low phenotypic standard deviation for milk yield correct for the heterogeneity of variance.