Effects of conjugated linoleic acid on growth, body composition, antioxidant status, lipid metabolism and immunity parameters of juvenile Chu's croaker, Nibea coibor

A-56 days feeding trial was conducted to evaluate the growth performance, feed utilization, biochemical composition, antioxidant status, lipid metabolism and immunity parameters of Chu's croaker Nibea coibor fed diets supplemented with different levels of conjugated linoleic acid (CLA): 0% (control), 0.5%, 1%, 1.5% and 2%. Each diet was randomly assigned to triplicate groups of 25 fish (initial body weight: 12.8 +/- 0.1g) in 15 floating cage. Weight gain (WG) and specific growth rate (SGR) were not significantly affected. 2% of dietary CLA led to significant lower lipid content in both whole body and liver (p<.05). Muscle lipid content was significantly lower in fish fed 1.5% and 2% CLA (p<.05). Saturated fatty acid (SFA) increased while monounsaturated fatty acid (MUFA) decreased with increasing dietary CLA in tissues (p<.05). Increasing CLA significantly promoted hepatic lipase (HL), lipoprotein lipase (LPL), serum lysozyme (LSZ) and immunoglobulin M (IgM) while decreased serum triglyceride (TG) in both liver and serum (p<.05). Liver Superoxide dismutase (SOD), catalase (CAT) and total antioxidant capacity (t-AOC) increased while malondialdehyde (MDA) decreased (p<.05). Our study shown that Chu's croaker can successfully incorporate CLA in tissues up to 2% dietary lipid without growth inhibition, and that CLA increased fish quality due to the increased parameters of lipid metabolism, specific immunity, hepatic antioxidant and CLA accumulation, and the reduction of tissue fat deposition.