Optimal dietary protein requirement for juvenile Trachinotus ovatus

An experiment on feeding and growth was conducted to determine the optimal dietary protein requirement for juvenile Trachinotus ovatus cultured in sea net cages (1.5 m1.0 m2.0 m). Fish meal and soybean meal were mixed as protein into the feed at 6 levels (30.32%. 35.56%, 41.48%, 47.86%, 51.70% and 54.70%)and 3 cages per level. Thirty juveniles at the initial weight of (24.390.23) g were fed in each net cage for 56 d. Result demonstrates that dietary protein affects specific growth rate (SGR) and feed efficiency rate (FER) significantly, which both increase with increasing dietary protein level from 30.32% to 41.48% significantly (P0.05), but show no significant difference above these levels. Juveniles fed with 47.86% proteinobtain the best SGR and FER. The protein content in juvenile T.ovatus increases with increasing dietary protein level. Finally, according to the broken-line regression analysis of SGR, the optimal dietary protein requirement for T.ovatus is about 45.75%.