Effects of resveratrol and genistein on nutrient digestibility and intestinal histopathology of rainbow trout (Oncorhynchus mykiss)

Abstract

Current trends in aquaculture production have led to the interesting approach of using plant-derived bioactives and phytochemicals in fish nutrition. The potential use of phytochemicals covers, among many other aspects, also the search for substances that increase the nutritional value of aquaculture products. Apart from the targeted beneficial effects, dietary supplements might exert adverse side effects. In this study, resveratrol and genistein were investigated for their effects on nutrient digestibility and intestinal histopathology of rainbow trout. A three-week digestibility trial was conducted with rainbow trout (144.2 ± 16.1 g) fed three experimental diets: diet CD was the control diet, diet RV was supplemented with resveratrol (0.3% dry matter of the diet), and diet G was supplemented with genistein (0.3% dry matter of the diet). The trial revealed slightly negative effects of the phytochemical-supplemented diets on the digestibility of dry matter (diet G), crude lipid (diet G), and gross energy (diets G and RV). The histopathological investigation of the hindgut revealed neither damage nor improvement of the intestinal morphology through resveratrol and genistein. Thus, microscopic changes and inflammation could be excluded as reason for the reduced digestibility. Overall, the effects of resveratrol and genistein on the digestibility of macronutrients are considered as one possible mechanism impairing growth and performance of rainbow trout.