Histological and enzymatic study of the liver of Nile tilapia (Oreochromis niloticus) during the replacement of blood powder instead of fish meal in the diet

Most tilapias are microphytic, but some prefer higher plants. The aim of this study was to evaluate the histomorphology of liver and enzymes under the influence of replacing blood powder with fish powder in the diet of Nile tilapia. After preparation, fish were fed with designed diets containing 0, 25, 50, 75, and 100% blood powder for 8 weeks, and each treatment was performed with three replications. After this period, the fish were anesthetized and blood samples were taken from the caudal stalk with a heparin syringe for liver enzymatic factors. The tissue samples were taken 0.5 cm from the liver, fixed in 10% formalin buffer, and after dehydration with alcohol, clarification with xylol, blocking with paraffin, cutting 4-6 microns thick with microtome were done. General and specific staining were performed and the study of microscopic slides was performed under a light microscope. The results of this study showed that in the group receiving whole blood powder, several complications such as sinusoidal hyperemia, diffuse vacuolar degeneration, necrosis of hepatocytes, and melanomacrophage were observed. The results of liver enzyme measurements in the treatment group had a higher level than the control group, with the difference that the level of ALT and AST had a more important role and the level of ALP had a lesser role. According to the results of this study, blood powder in the diet is somewhat tolerable and replaceable for the species.