In this study, the villus height in the YC-4 and YC-0 groups and the villus width in the YC-0 group were significantly reduced, and the diamine oxidase activity and D-lactic acid content in the YC-4 and YC-0 groups were significantly increased, indicating that intestinal structure was damaged and intestinal inflammation was induced when a high level of fish meal was substituted by yeast culture. This evidence concerns the gene AOC1 and inflammatory response.