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In this study, growth performance data from finishing pigs indicate the response of barrows and gilts to dietary protein concentration was maximized with a 15 percent protein corn-soybean meal diet. Review of the response of plasma urea concentration to dietary protein intake indicated that, in this study, the protein requirement of barrows was between 12 and 15 percent and the protein requirement for gilts was between 15 and 18 percent. Based on the many findings in the literature documenting that protein requirements ( percent of the diet) of gilts are greater than those of barrows, we believe the use of plasma urea is an alternative approach to using growth performance data for establishing the protein (amino acid) requirements of finishing pigs. Identifying a small number of pigs for blood sampling may provide a less intensive method to help gain insight into the protein requirements of barrows and gilts during the finishing period. Future research will focus on refining the plasma urea technique to identify the response of barrows and gilts to dietary protein. Specifically, we are interested in pursuing the application of this methodology to commercial conditions.