Energy and protein requirements of yellowtail during winter season

SUMMARY: This study was conducted to determine the energy and protein requirements of yellowtail during the winter season (12.8–16.5oC) when they have a comparatively low feeding activity. The feeding experiment was conducted in net cages (3 × 3 × 3 m) located at Mie Prefecture, Japan. The fish (745–758 g) were split into six groups: the first five were fed to satiation, and at 70, 50, 30, and 10% of satiation levels, respectively, while the sixth group was starved. The experimental diets were commercial soft-dry pellets (SDP) with known digestible energy (DE) and protein (DP) values. The groups were fed three times a week for 4 weeks. The growth rate was highest in the satiation group and decreased with decreasing feeding levels. The DE and DP requirements were 42.1 kcal and 3.3g/kg BW/day for maximum growth and 14.7 kcal and 1.1 g/kg BW/day for maintenance of body weight. The DE and DP requirements for the maintenance of body energy content were estimated to be 19.6 kcal and 1.5 g/kg BW/day, respectively.