Effects of Dietary L-carnitine and Lipid Supplementation on Growth Performance, Survival and Body Composition of Grouper Larvae, ＂Epinephelus lanceolatus＂

Abstract

A feeding experiment was conducted to study the effects of dietary L-carnitine and lipid levels on the growth, muscle and liver fatty acid profile of Epinephelus lanceolatus larvae (initial mean weight 0.136 g). Two levels of supplemental lipid, 5 or 14% were tested in combination with three levels (0, 0.5 and 1%) of L-carnitine. Each diet was randomly assigned to three replicate groups of groupers larvae for 42 days. The fatty acid compositions of grouper larval muscle and liver were influenced by dietary L-carnitine and lipid. The n-3 high unsaturated fatty acids (n-3 HUFA) of muscle and liver of grouper larvae fed diets supplemented with L-carnitine were significantly lower than that of grouper larvae fed diets without L-carnitine. The grouper larvae fed diets containing 14% lipid had the significantly higher weight gain than those fed diets containing 5% lipid. The grouper larvae fed diets containing 5% lipid and without L-carnitine supplementation had the worst weight gain. The grouper larvae fed diets containing 14% lipid and supplemented with 0.5% L-carnitine had the highest weight gain among treatments. The hepatosomatic index (HSI) of grouper larvae increased with dietary lipid increasing, while HSI of grouper larvae decreased with the increasing dietary L-carnitine. Lipid contents of muscle and liver of grouper larvae increased with increasing dietary lipid level, whereas lipid levels of muscle and liver of grouper larvae fed diets supplemented with L-carnitine decreased. The muscle protein content significantly increased with increasing dietary L-carnitine. The survival of grouper larvae fed diet containing 14% lipid was significantly higher than that of grouper larvae fed diets containing 5% lipid. This study revealed the positive effects of dietary L-carnitine supplementation on growth of grouper larvae.