Livestock resource management through gender offspring preselection is an efficient tool in terms of genetic improvement and farm management and additionally provides the opportunity to adjust offspring to market demands. In this study bull ejaculates were tested using PCR amplification of a segment of the X-Y homologous amelogenin gene in order to estimate the X and Y chromosome frequencies by capillary electrophoresis. Results were quantified against a regression function constructed with pools prepared with DNA from bulls and cows with known X and Y ratios. An average of 50.02 +/- 2.79% X chromosome content was found with normal distribution ranging from 38.7 to 58.2%. Bull effect was significant in the analysis of variance representing 8.5% of the total variance. This simple analysis provides a low-cost and quick method of evaluating an X-Y ratio in a high number of ejaculates, particularly when external factors can be manipulated to alter it.