Dietary modulation of digestive enzymes by the administration of feed additives to rainbow trout, Oncorhynchus mykiss Walbaum

Abstract

The aim of this study was to assess the metabolic and digestive enzyme activities in rainbow trout, Oncorhynchus mykiss Walbaum fed dietary supplements. The biometric indices and the following enzymes activities were measured: acid protease and pepsin from the stomach homogenates, alkaline phosphatase (AP) from the small intestine and the brush border membrane, total proteolytic enzymes and trypsin from the small intestine and liver/pancreas. Dietary garlic induced a higher pepsin activity in the stomach than lipopolysaccharide (LPS) and ginger. Conversely, dietary ginger and LPS showed a significant difference (P less than 0.05) in acid protease activity compared to the controls. There was not any significant difference observed between treated groups and the controls for hepato-pancreas proteolytic enzyme activity, except for trypsin. AP activity increased significantly with dietary garlic, ginger and LPS compared to the controls.