Effects of dietary conjugated linoleic acids on hepatic and muscle lipids in hybrid striped bass

Conjugated linoleic acids (CLA) are the focus of numerous studies, yet the effects of these isomers of octadecadienoic acids have not been evaluated i n many species of fish. In this study, graded amounts of CLA-0, 0.5, 0.75, or 1.0% of the diet-were fed to juvenile hybrid striped bass for 8 wk. Diet ary treatments were fed to apparent satiation twice dal ly to triplicate gr oups of fish initially weighing 13.4 g/fish. Feed intake and weight gain of fish fed 1.0% CLA were significantly reduced compared to fish fed no CLA. Fish fed 0.5 and 0.75% CLA exhibited reduced feed intake similar to fish fe d 1.0% CLA, but had growth rates that were not significantly different from those of fish fed no CLA. Feed efficiency improved significantly in fish a s dietary CLA concentrations increased. Total liver lipid concentrations we re significantly reduced in fish fed the diets containing CLA compared to t hose of fish fed the control diet, and intraperitoneal fat ratio was signif icantly lower in fish fed 1.0% CLA compared to fish fed no CLA. Fish fed di etary CLA exhibited significant increases in hepatosomatic index and moistu re content of muscle and carcass, The CLA isomers were detected in liver an d muscle of fish fed the diets containing CLA, while a low concentration of one isomer was detected in liver and muscle of fish fed the control diet. Dietary CLA resulted in a significant increase in 18:2(c-9,c-12) concentrat ion in liver and muscle, but a significant reduction in 18:1n-7 in these ti ssues. Furthermore, feeding CLA resulted in a significant increase in the c oncentration of 20:5n-3 and 22:6n-3 in liver, but a reduction of these fatt y acids in muscle. This study showed that feeding CLA elevated tissue conce ntrations of these fatty acid isomers, reduced tissue lipid contents, impro ved feed efficiency, and altered fatty acid concentrations in liver and mus cle of fish.