Effect of dietary protein and lipid levels on growth, nutrient utilization and whole‐body composition of blue gourami, <i>Trichogaster trichopterus</i> fingerlings

Abstract

Nine semi-purified diets were prepared with three levels each of protein (300, 350 and 400 g/kg) and lipid (60, 80 and 100 g/kg) and fed ad libitum to Trichogaster trichopterus fingerlings (0.61 ± 0.03 g) in triplicate groups (10 fish/replicate) for 90 days to determine optimum dietary protein and lipid levels. Twenty-seven flow-through fibre-reinforced plastic tanks (200 l capacity each with 100 l of water) were used for rearing the fish. The dietary protein, lipid and their interactions had significant effects (p < 0.05) on weight gain, feed conversion ratio, specific growth rate, nutrient retention and digestibility, but not on hepato- and viscerosomatic indexes (p > 0.05). Dietary protein and the interaction of protein with lipid had significant effect (p < 0.05) on whole-body dry matter, lipid and energy contents, but not on protein and ash contents (p > 0.05). But, the dietary lipid had significant (p < 0.05) effect on whole-body dry matter, protein, lipid and energy contents except the ash contents (p > 0.05). For each level of dietary protein, the increase in dietary lipid resulted significant increase (p < 0.05) in whole-body lipid contents without affecting the protein and ash contents (p > 0.05). Based on better growth and dietary performances, the optimum dietary protein and lipid levels of blue gourami fingerling are 350 and 80 g/kg diet respectively.