Histological and morphometrical analyses of small intestine by hematoxylin-eosin (H&E) staining. Con, the basal diet without antibiotics, tributyrin, oregano or methyl salicylate; AB diet, the basal diets supplemented with an antibiotic compound, which provides the diet with 120 mg oxytetracycline-calcium and 16 mg enduracidin per kilogram; OT and MT diets, the basal diet supplemented with tributyrin plus oregano (1.4 g and 0.6 g per kilogram diet) and tributyrin plus methyl salicylate (1.4 g and 0.6 g per kilogram diet), respectively. Villus height and crypt depth for the small intestine are in Table 4. The measurement of villus height (from the tip of the villous to villous-crypt junction) and crypt depth (from the villous-crypt junction to the lower limit of the crypt) were recorded as the mean of 10 fields for specimen. Scale bars: 100 μm.