Soybean meal (SBM) is often included in cereal-based diets for growing pigs because it provides a well-balanced profile of digestible amino acids (AA), which maximizes growth performance and protein synthesis. However, in recent years, SBM has often been partially replaced by crystalline AA or alternative protein sources such as corn distillers dried grains with solubles (DDGS) or corn protein. These co-products are by-products of the ethanol and vegetable oil industries and are commonly used in swine diets due to their availability and lower cost. Although they provide some indispensable AA, they have a less balanced AA profile and greater fiber concentrations than SBM, which may result in reduced AA digestibility, nitrogen retention, and energy utilization in pigs. However, pigs have become leaner and have greater requirements for dietary AA to support protein synthesis. In addition, it is often assumed that replacing SBM with corn and crystalline AA increases the energy of the diet, but recent data indicate that SBM may provide as much or more digestible energy (DE) and metabolizable energy (ME) than previously estimated. Therefore, it is possible that replacing SBM with corn co-products and crystalline AA may result in a reduction of nitrogen and energy utilization and increase nitrogen excretion in manure. Therefore, the objective of this work was to test the hypothesis that feeding intact protein from SBM to growing pigs, instead of combinations of SBM with crystalline AA or co-products such as DDGS or corn protein, results in greater nitrogen retention and greater DE in the diet without affecting ME.