Effects of different dietary glycyrrhetinic acid (GA) levels on growth, body composition and plasma biochemical index of juvenile channel catfish, Ictalurus punctatus

Glycyrrhetinic acid (GA), the main active constituents of Glycyrrhiza glabra roots, is extensively used as food additives and herbal medicines. This study was carried out to evaluate the effects of different dietary levels of GA on growth, body composition and plasma biochemical index of channel catfish (average weight, 159.0 +/- 5.0 g). Five diets were formulated to contain five levels of GA (0, 0.075, 0.15, 0.3 and 0.6 g/kg). Fish were randomly distributed into 30 tanks and fed three times daily (08:30, 12:00 and 16:30 h) for 8 weeks. Dietary GA levels have little significant effect on weight gain (WG) and feed conversion ratio (FCR). Intraperitoneal fat ratio (IFR) (P<0.05) and viscera/body ratio (VBR) (P<0.01) decreased significantly as GA levels increased, and hepatosomatic index (HSI) tended to decrease as dietary GA levels increased (P<0.1). Lipid content of liver decreased significantly as GA concentrations increased (P<0.01), and lipid content of muscle tended to decrease as dietary GA concentrations increased (P<0.1). Plasma triglycerides (TG) and total cholesterol (CHO) were decreased as dietary GA concentrations increased (P<0.05); whereas, plasma cortisol and glucose (GLU) showed an opposite tendency (P<0.05). Results of this study indicate that 0.3 g/kg GA had a positive influence in improving lipid deposition in channel catfish without negative effect on growth; the beneficial effect may be due to promoting lipolysis. (c) 2012 Elsevier B.V. All rights reserved.