Resumo

MAGANA-VALENCIA, Fabián; NUNEZ-DOMINGUEZ, Rafael; RAMIREZ-VALVERDE, Rodolfo  e  RODRIGUEZ-ALMEIDA, Felipe A.. Connectedness in animal genetic evaluations: 2. Comparison of methodologies. Agrociencia [online]. 2013, vol.47, n.8, pp.781-794. ISSN 2521-9766.

The purpose of this study was to compare the main methods to estimate connectedness among contemporary groups (CG) in a simulated population, considering a single structure of data. A population of 37 cattle was simulated, of which 15 had records of weaning weight in one of three CG, in seven scenarios with different degrees and types of connectedness (direct and indirect). In each scenario contrasts were performed among the CG and their connectedness was determined with 10 quantitative methods. The criteria for comparing the methods were: capacity to identify CG disconnected, and connected directly or indirectly; and consistency, defined as the relationship between the degree of obtained vs. simulated connectedness by progressively increasing the number of sires and dams in common among CG, through the scenarios. In addition, correlation coefficients were obtained between the degrees of connectedness. The prediction error variance methods of the differences in genetic values among animals, gene flow, total number of direct genetic links due to common sires and dams, and connectedness index showed trends in connectedness values consistent with the increase in the number of sires or dams in common through the seven simulated scenarios. Of these methods, only that of number of direct genetic links detected disconnected contemporary groups, besides being highly correlated (-0.97) with the prediction error variance of the differences in genetic values among animals. Therefore, it is suggested to use the method of total number of direct genetic links in routine genetic evaluations of cattle.

Palavras-chave : genetic connectedness methods; genetic evaluation; animal model; simulation.

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