Effects of Dietary Lipid Levels and Energy: Protein Ratios on Growth and Feed Utilization of Juvenile Nassau Grouper Fed Isonitrogenous Diets at Two Temperatures

Abstract The growth and feed utilization of juvenile Nassau grouper Epinephelus striatus (mean weight = 2.12 g; N = 9) were compared for 75 d in laboratory aquaria supplied with flow-through seawater. Fish were fed four isonitrogenous (45% crude protein) diets differing in lipid content (6, 9, 12, or 15% dry weight) and energy: protein (E:P) ratio (28.4, 31.0, 33.5, or 36.0 kJ/g protein) at two temperatures (25°C and 30°C). Specific growth rates and final weights increased (P < 0.001) with decreasing dietary lipid and E:P ratios, from a minimum of 1.20% of body weight (bw) per day (5.21 g) for fish fed the 15% lipid diet to a maximum of 2.04% bw/d (9.31 g) for fish fed the 6% lipid diet. The specific growth rate was greater (P < 0.01) at 30°C (1.38–2.09%/d) than at 25°C (1.02–1.99%/d). Feed consumption (2.16–3.30% bw/d) was inversely correlated (P < 0.001) to dietary lipid content and E:P ratio and was greater (P < 0.005) at 30°C than at 25°C. Feed conversion ratio (1.91–2.74) was positively correlated an...