Effects of dietary protein and energy levels on the growth Index and body composition of juvenile yellowfin seabream (Acanthopagrus latus)

A feeding trial was carried out where, three protein concentrations [45%, 55% and 65%) crude protein (CP)] and three dietary energy concentrations [20, 22and 24 kj g-1 crude energy (CE)] were fed to 540 yellowfin seabreams (Acanthopagrus latus) fingerlings to establish the protein and energy requirement for this species. 9 treatments with triplicate groups of 20 fish each (initial weight 12g) were stocked in 300-L fiberglass tanks and fed twice a day to apparent satiation. After 8 weeks, the survival rate was not dependent on the dietary treatments, but average fish weight gain (AWG), specific growth rate (SGR) and feed efficiency ratio (FER) were significantly affected by dietary protein (P<0.05). Protein retention (PR) were increased by dietary energy level (P<0.05). Feed efficiency ratio, PER and Hepatosomatic Index (HIS) was not affected by dietary protein and energy concentrations (P>0.05). At same protein level, PER, PR increased with the increase in energy levels from 20 to24 Kj g-1. Carcass moisture and ash contents were significantly affected by dietary protein and energy levels (P<0.05) but carcass protein was not significantly affected by dietary protein and dietary energy levels (P>0.05). With increase dietary energy, carcass fat content was increased from 20 to 24 Kj g-1. The results indicate that the optimum dietary protein and energy levels for growth of juvenile yellowfin seabream are 56. 20 – 57. 47g in Kg-1diet and 21.9-24.56Kj in gr diet and 23.15-25.95mgr kg-1, respectively.