In the United States and most other countries in the world, soybeans and their co-products are a staple in livestock and human diets as a source of dietary protein. Soybeans have a relatively consistent nutrient profile with high crude protein levels, but they contain various antinutritional factors that affect nutrient utilization, such as trypsin (protease) inhibitors, lectins, oligosaccharides, and -mannans. Hypertrophy of the pancreas and increased pancreatic secretions are a compensatory adaption to a diet high in trypsin inhibitors. Research has not yet determined an official minimum level of residual anti-proteolytic activity (trypsin inhibitors) for commercial soybean products in poultry diets. In the present studies, we determined how trypsin inhibitors affect the nutritional value of soybean products and broiler growth and performance. Broilers were found to adapt to antinutritional factors as they age, but any change to the level of trypsin inhibitors negatively impacted performance, and increased relative pancreas weights