TAILIEUCHUNG - Báo cáo sinh học: " Modeling relationships between calving traits: a comparison between standard and recursive mixed models"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học quốc tế đề tài: Modeling relationships between calving traits: a comparison between standard and recursive mixed models | de Maturana et al. Genetics Selection Evolution 2010 42 1 http content 42 1 1 Ge n et i cs Selection Evolution RESEARCH Open Access Modeling relationships between calving traits a comparison between standard and recursive mixed models Evangelina Lopez de Maturana1 2 Gustavo de los Campos1 Xiao-Lin Wu3 Daniel Gianola1 3 4 Kent A Weigel3 Guilherme JM Rosa3 Abstract Background The use of structural equation models for the analysis of recursive and simultaneous relationships between phenotypes has become more popular recently. The aim of this paper is to illustrate how these models can be applied in animal breeding to achieve parameterizations of different levels of complexity and more specifically to model phenotypic recursion between three calving traits gestation length GL calving difficulty CD and stillbirth SB . All recursive models considered here postulate heterogeneous recursive relationships between GL and liabilities to CD and SB and between liability to CD and liability to SB depending on categories of GL phenotype. Methods Four models were compared in terms of goodness of fit and predictive ability 1 standard mixed model SMM a model with unstructured co variance matrices 2 recursive mixed model 1 RMM1 assuming that residual correlations are due to the recursive relationships between phenotypes 3 RMM2 assuming that correlations between residuals and contemporary groups are due to recursive relationships between phenotypes and 4 RMM3 postulating that the correlations between genetic effects contemporary groups and residuals are due to recursive relationships between phenotypes. Results For all the RMM considered the estimates of the structural coefficients were similar. Results revealed a nonlinear relationship between GL and the liabilities both to CD and to SB and a linear relationship between the liabilities to CD and SB. Differences in terms of goodness of fit and predictive ability of the models considered were negligible suggesting .

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