Effects of different dietary lipid(energy) to protein ratios on growth of juvenile zander (Lucioperca lucioperca)

This experiment was conducted to study growth performance of juvenile zander［initial average weight（7.75±1.17） g］fed five formulated diets with different lipid(energy) to protein ratios.The results showed：The specific growth ratio［SGR (2.86±0.17)%/d］,feed coefficient ratio(FCR 1.57±0.12),protein deposit ratio(PDR 98.44%±2.38%),energy retention ratio(ERR 30.88%±3.83%) performed the best in group 4 after being fed the different diets；Using the second-order polynomial regression analysis, the optimum protein，the optimum lipid，the optimum gross energy(GE)，the optimum lipid to protein ratio(L/P) and the optimum energy to protein ratio(E/P) in diets for juvenile zander (Lucioperca lucioperca) were estimated based on SGR, PDR and ERR of the juveniles. When SGR was the highest, the optimum protein, the optimum lipid, GE, L/P and E/P were estimated to be 39.80%,8.79%,18.53 MJ/kg,0.22,46.56 kJ/g；When PDR was the highest, the optimum protein, the optimum lipid,GE,L/P and E/P were estimated to be 38.76%,9.18%,18.65 MJ/kg, 0.24, 48.12 kJ/g；When ERR was the highest, the optimum protein, the optimum lipid, GE, L/P and E/P were estimated to be 38.55%,9.45%,18.72 MJ/kg, 0.25, 48.56 kJ/g；The requirement for protein used for energy is decreased when dietary lipid level increases.It was suggested that dietary lipid had significant protein-sparing effect on this fish. But zander (Lucioperca lucioperca) utilizes the lipid definitely；When E/P was as high as 58.79 kJ/g or as low as 42.54 kJ/g，WGR，PDR and ERR were significantly lower,FCE was significantly higher(P<0.05) than other E/P levels，indicating that diets with too high E/P level or low E/P level would inhibit the growth and feed utilization of juvenile zander.