Effects of dietary protein and lipid levels on growth, feed utilization and body composition in red-tailed catfish juveniles (Hemibagrus wyckioides,Chaux & Fang 1949)

Abstract

A feeding trial was conducted in a recycling water system during 10 weeks to determine the optimal protein to lipid ratio in Asian red-tailed catfish (Hemibagrus wyckioides). Six diets of two protein levels (390 and 440 g kg−1) with three lipid levels (60, 90 and 120 g kg−1) were formulated. Fish (1.96 g) were fed six diets with four replicates to apparent satiation at a stocking density of 50 fish per tank (500 L). Faeces were collected in cultured tanks at the end of the feeding trial for digestibility measurement. Significantly, improved growth performances (P < 0.01) and higher feed utilization (P < 0.001) were observed in fish fed with higher lipid diets. However, higher protein diets did not significantly improve fish growth but they reduced FCR (P < 0.001) and protein efficiency ratio (P < 0.01). Higher lipid diets also resulted in significantly increased adipose-somatic index, carcass fat and reduced moisture of the fish. The study revealed the protein sparing effect of dietary lipid in the catfish and highest growth performance was found by fish fed 390 g kg−1 protein and 120 g kg−1 lipid diet with P/E ratio of 20.48 mg protein kJ−1. DP/DE ratio for maximal growth rate in diets was 21.48 mg protein kJ−1.