Effects Of Dietary Lipid (Energy) To Protein Ratios On Growth And Metabolism Of Juvenile Zander (Lucioperca Lucioperca)

Five diets were formulated to study the growth and metabolism of juvenile zander (Lucioperca lucioperca),which is an important commercial species of perch, as influenced by different dietary lipid (energy) to protein ratio levels. Tow series of experiments were conducted in this study.In experimentⅠ, the growth performance of juvenile zander ( initial average weight 7.75±1.17g) was studied by a 75-day feeding trial. The results showed:①The specific growth rate (SGR 2.86±0.17%·d-1), feed coefficient(FCE 1.57±0.12), protein deposit rate (PDR 98.44±2.38%),energy retention rate(ERR 30.88±3.83%) performed the best in group 4 after feeding the different diets.②using 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/Pand 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/Pand 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/Pand E/P were estimated to be 38.55%,9.45%,18.72 MJ/kg, 0.25, 48.56 KJ/g;③The requirement for protein which used for energy is decreased when dietary lipid level increase. It was suggested that dietary lipid had significant protein - sparing effect on this fish. But zander (Lucioperca lucioperca) utilize the lipid definitely.④When E/P as high as 58.79KJ/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;⑤Significant difference was found in Carcass composition (moisture,crude protein,lipid,ash) and physique of zander by feeding the diets containing different protein and lipid levels (P<0.05).In experiment II,influence of feeding the diets which is used in experiment I on oxygen consumption and ammonia excretion was studied to test relation between oxygen consumption,ammonia excretion and the different E/P levels during specific dynamic action (SDA),by a continuous-flow respirometer at 20±0.2℃.The results as follows:①After feeding,oxygen consumption rate and ammonia excretion rate increased drastically, and reached their maximum levels in a short time,then decreased slowly to the levels before feeding. The peak,the time to peak,the magnitude and the SDA duration of the ammonia excretion rate were similar to those of the oxygen consumption.②Both of the oxygen consumption and the ratio of ammonia excretion were linear increased significantly(p<0.05) with decrease in dietary E/P level, the oxygen consumption increased(OC1