A three-stage in vitro model was used to simulate the digestion of wheat in the broiler chicken. During digestion simulation, much of the wheat protein was liberated into the supernatant. Microscopic examination of the residue showed that protein could be detected only within unbroken cells. Intact starch granules were clearly visible following digestion simulation and only a small amount (ca. 8%) of glucose was released into the supernatant. The effects of enzymes from Trichoderma reesei on wheat cell structure and the release of protein and non-starch carbohydrate were studied. Addition of cell wall degrading enzymes increased the release of proteins and non-starch carbohydrate. The hydrolysis of wheat cell walls increased with concentrations of cell wall degrading enzymes. Microscopy results were consistent with those from chemical analysis.