The experiment aimed to evaluate the growth, the nitrogen metabolism and liver and muscle composition of juvenile pompano Trachinotus marginatus fed with different protein levels (PB43, PB54, PB64). Groups of 10 juveniles (1.47±0.14g) were stocked in nine tanks with 50L in a marine recirculating aquaculture system during 55 days. Fish were fed four times a day. The weight gain, specific growth rate and feed conversion rate did not present significant differences (P>0.05). However, the increase in protein consumption augmented the hepatosomatic index, the pos prandial ammonia excretion rate and reduced the protein efficiency rate. Fish fed with PB43 presented lower hepatic glutamic oxaloacetic transaminase and lower concentration of triglycerides in muscle and liver (P<0.05). Carcass composition, glycogen and muscle and liver protein content did not present significant differences (P>0.05), with the exception of the lipid content in fish carcass fed with PB43. It is concluded that the better protein utilization in juvenile pompano is observed when they are fed with 43% protein.
ammonia; protein; transaminases; Trachinotus marginatus
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