Effects of Dietary Lipid, L-carnitine and L-lysine Supplementation on the Growth Performance and Body Composition of Epinephelus lanceolatus Larvae

Abstract

The effects of different combinations of dietary lipid, L-carnitine and L-lysine on the growth performance and fatty acid profiles of larval grouper Epinephalus lanceolatus were evaluated. Eight treatment diets were formulated based on a 2 x 2 x 2 factorial design, namely 5 and 14% dietary oil mixture (3:1 fish oil/soybean oil), 0 and 0.5% L-carnitine and 0 and 2.83% L-lysine. Each diet was randomly assigned to triplicate groups of ten 0.08 g E. lanceolatus larvae for 42 days. The grouper larvae fed with diets containing 14% lipid had significantly higher weight gain percentages than those fed with diets containing 5% lipid. The weight gain percentage of the grouper larvae fed with a diet containing both 14% lipid and 0.5% L-carnitine without added L-lysine was found to be the highest, while the addition of dietary 2.83% L-lysine failed to have any additive effect on the growth performance. With the dietary lipid being 14%, not only dietary L-carnitine but also L-lysine is able to decrease lipid and increase protein levels in grouper muscle. The supplementation of dietary L-carnitine with a high level of lipid is also able to reduce liver lipid level of groupers. The levels of n-3 highly unsaturated fatty acid (n-3 HUFA) analyzed from muscle and liver of grouper larvae fed with diets supplemented with L-carnitine were significantly lower than those of grouper larvae fed with diets devoid of L-carnitine. This study indicated that the diets containing a high lipid level supplemented with L-carnitine are able to enhance the growth performance of grouper larvae.