Metabolic requirements of red drum, Sciaenops ocellatus, for protein and energy based on weight gain and body composition.
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Precise formulation of diets that meet but do not greatly exceed nutritional requirements should assist in lowering feed costs for commercial aquaculture of red drum, Sciaenops ocellatus. In this study, protein and energy requirements of red drum for maintenance and maximum gain were determined by feeding a diet containing digestible protein (DP) at 36.5% and 14.2 kJ digestible energy (DE) per gram at various rates for 8 wk in two separate experiments. Changes in weight and whole-body energy and protein were measured and regressed against protein or energy fed using a nonlinear procedure. In the first experiment, juvenile fish [ approximately 3. 4 g initial body weight (BW)] were either starved or fed at one of the following g/(100 g BW.d): 0.5, 1, 2, 4, 6, or 8. The second experiment utilized larger red drum (approximately 5.5 g initial weight), fed 0.75, 1.5, 3, 5, 5.5, 6, 6.5 or 7 g/(100 g BW.d) to confirm and refine results from the first experiment. Based on maintenance of body weight in both experiments, red drum had a protein maintenance requirement of 1.5 and 2.5 g DP/(kg BW.d) whereas estimates based on maintenance of whole-body protein were 0.5 and 2.2 g DP/(kg BW.d). Energy requirements for maintenance of weight and body energy ranged from 58 to 93 and 92 to 97 kJ DE/(kg BW.d), respectively. Protein requirements for maximum weight gain and change in body protein ranged from 20 to 25 g DP/(kg BW.d), whereas energy requirements for maximum weight gain and whole-body deposition ranged from 776 to 958 and 914 to 985 kJ DE/(kg BW.d), respectively. These requirements for maintenance and maximum gain of red drum should assist in formulation of diets for a variety of desired feeding strategies.