Study of the effect of pultry by-product replacement instead of fish meal on skin cell profile of Nile tilapia (Oreochromis niloticus)

The main purpose of the present study was to investigate the effect of pultry by-product powder replacement instead of fish meal at levels of 0, 25, 50, 75 and 100% on structure of skin tissue of Nile tilapia. After 8 weeks, 5 specimens of each treatment were selected. After biometrics 0.5 centimeter specimen dorsal of head, middle of the trunk and caudal stalk were removed and immediately were placed in 10%formalin buffer. Rutine procedure of tissue prepration was done and sections of 4-6 micron thicknesses were stained by hematoxylin-eosin (H&E), periodic acid schiff (PAS) and masson's trichrome histochemistry staining. Microscopic results showed that in control group mucosal cells count, taste buds count, epiderm thickness and collagen thickness increased compared to other groups. Instead in group fed100% pultry by-product increased club cells count and chromatophore thickness compared to other groups and there was a significant difference to some groups (p≤0.05). According to the results of this study, it can be concluded that pultry by-product powder replacement instead of fish meal up to 100 % is tolerable for Nile tilapia. Because according to this study, no lesions or adverse effects on the histomorphology of skin were reported.