The objective of this study was to verify if fitting line composition in the model to analyze an admixed population would impact accuracy of pedigree and genomic estimated breeding values (EBV). Fitting line composition improved predictive ability for some traits in pedigree based analyses. In genomic prediction analyses, the accuracies for traits with high heritabilities were not affected by fitting line composition, whereas for lower heritability traits either positive or negative effects were observed. It was more important to correct for population structure in pedigree-based than in genomic analyses.