A 56-day feeding trial was conducted to examine the dietary leucine requirement of juvenile Japanese seabass in sea- water floating net cages （1.5 m × 1.5 m × 2.0 m）. Six isonitrogenous （crude protein 40%...A 56-day feeding trial was conducted to examine the dietary leucine requirement of juvenile Japanese seabass in sea- water floating net cages （1.5 m × 1.5 m × 2.0 m）. Six isonitrogenous （crude protein 40%） and isoenergetic （gross energy 20 kJ g-1） diets were formulated to contain different concentrations of leucine （0.9%, 1.49%, 2.07%, 2.70%, 3.30% and 3.88% of dry matter）. Crys- talline L-amino acids were supplemented to simulate the whole body amino acid pattern of Japanese seabass except for leucine. Three groups （30 fish individuals each, 8.0g±0.20g in initial weight） were fed to apparent satiation at 5：00 and 17：30 every day. During the experimental period, the water temperature ranged from 26 to 32℃ and salinity from 26 to 30, and the dissolved oxygen was maintained at 7mgL-l. The results showed that weight gain （WG）, nitrogen retention （NR）, feed efficiency （FE） and protein efficiency ratio （PER） were significantly increased when dietary leucine was increased from 0.90% to 2.70% of dry matter, and then declined. WG was the highest when fish were fed D4 containing 2.70% of leucine. No significant differences were observed in body composition among dietary treatments （P 〉 0.05）. Considering the change of WG, the optimum dietary leucine requirement of juve- nile Japanese seabass was either 2.39% of dry matter or 5.68% of dietary protein.展开更多
基金supported by the National Key Technologies R&D Program for the 15th Five-year Plan of China (Grant no. 2004BA526B-06)Program for New Century Excellent Talents in University (NCET-07-0776)
文摘A 56-day feeding trial was conducted to examine the dietary leucine requirement of juvenile Japanese seabass in sea- water floating net cages （1.5 m × 1.5 m × 2.0 m）. Six isonitrogenous （crude protein 40%） and isoenergetic （gross energy 20 kJ g-1） diets were formulated to contain different concentrations of leucine （0.9%, 1.49%, 2.07%, 2.70%, 3.30% and 3.88% of dry matter）. Crys- talline L-amino acids were supplemented to simulate the whole body amino acid pattern of Japanese seabass except for leucine. Three groups （30 fish individuals each, 8.0g±0.20g in initial weight） were fed to apparent satiation at 5：00 and 17：30 every day. During the experimental period, the water temperature ranged from 26 to 32℃ and salinity from 26 to 30, and the dissolved oxygen was maintained at 7mgL-l. The results showed that weight gain （WG）, nitrogen retention （NR）, feed efficiency （FE） and protein efficiency ratio （PER） were significantly increased when dietary leucine was increased from 0.90% to 2.70% of dry matter, and then declined. WG was the highest when fish were fed D4 containing 2.70% of leucine. No significant differences were observed in body composition among dietary treatments （P 〉 0.05）. Considering the change of WG, the optimum dietary leucine requirement of juve- nile Japanese seabass was either 2.39% of dry matter or 5.68% of dietary protein.
