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Energy and protein requirements for maximum growth and maintenance of bodyweight of yellowtail


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Six feeding experiments were conducted to determine energy and protein requirements of different sized yellowtail seriola quinqueradiata (8–280 g) for maximum growth and maintenance of bodyweight under different water temperatures (21.7–27.1°C) in 500 L polycarbonate tanks. For each experiment, fish were fed to satiation or fed at levels between 0 and 80% of the satiation level twice a day. The experimental diets were extruded dry pellets with known digestible energy (DE) and protein (DP) values. The growth rate was highest for the satiation group and decreased proportional to the feeding levels. The DE (kcal/kgBW per day)and DP (g/kgBW per day) requirements for maximum growth, calculated on the basis of the daily feeding rate of the satiation group, were 225 and 21.7, 136 and 14.8, 125 and 11.2, 111 and 10.7, and 92 and 8.2, respectively, for fish with an average initial bodyweight of 8, 63, 160, 237, and 280 g. The requirements for maintenance of bodyweight, based on when the growth rate was zero for the above sizes, were 61 and 5.9, 15 and 1.7, 15 and 1.3, 24 and 2.3, and 12 and 1.0, respectively. The requirements for maintenance of body energy content, estimated on the basis of the relationship between the DE intake and energy retention, were significantly higher than those for maintenance of bodyweight.