Growth, feed utilization and body composition of juvenile golden pompano Trachinotus ovatus fed at different dietary protein and lipid levels

A feeding trial was conducted to determine the suitable dietary protein and lipid levels for juvenile golden pompano Trachinotus ovatus reared in net pens. Ten test diets were formulated at five levels of crude protein (330, 370, 410, 450 or 490gkg1) and two levels of crude lipid (65 or 125gkg1). Golden pompano fingerlings (initial body weight 4.7gind1) were fed the test diets for 8weeks. Weight gain (WG), specific growth rate (SGR), feed conversion ratio (FCR), nitrogen retention efficiency (NRE), energy retention efficiency (ERE), condition factor (CF), hepatosomatic index (HSI), body protein content and total nitrogen waste (TNW) were dependent on both dietary protein and lipid levels. Feed intake (FI) and viscersomatic index (VSI) were dependent on dietary protein level, while body lipid content was dependent on dietary lipid level. Weight gain increased with increasing the dietary protein level (at the same lipid level) but was lower at the dietary lipid level of 65gkg1 than at 125gkg1 (at the same protein level). Fish fed at the dietary protein levels of 460490gkg1 had higher WG and lower FCR than at 330410gkg1. Energy retention efficiency tended to increase with increasing the dietary protein level from 330 to 410gkg1, while no significant difference was found in nitrogen retention efficiency between the dietary protein levels (at the same lipid level). Results of this study suggest increasing the dietary lipid level from 65 to 125gkg1 could not induce protein-sparing action in golden pompano, and the suitable dietary protein and lipid levels for juvenile golden pompano reared in net pens should be 450490 and 65gkg1.