Studies on the Effect of Lipid Levels on Dietary Protein Needs in Fish (Tilapla Nilotica)

This work wa~’ carried out in two experiments:Experiment I:This experiment was designed to determine the optimumprotein requirements for growth performance) bodycomposi tion and digestibility of nutrients in T.niloticaf Lng e r Li ng s , using 130 fishes (6 gm average body weight)which were divided into equal 5 dupl ica te groups in glassaquaria. Fish groups were fed on 5 isocaloric dietscontaining different levels of C. protein (25) 30) 35) 40and 45%) according to body weight. Fish were weighed every2 weeks intervals and measured their growth rates) foodconversion ratio) feed conversion efficiency) proteinefficiency ratio also the digestibility of these diets andwhole body composition of fish were determined.Results can be summarized into the following:1- Higher dietary protein (45%) gave high growth at thefirst 6 weeks while depressed it in the last 10 weeks.2- The growth rate was increased by increasing dietaryprotein from 25 to 30% and was depressed at proteinlevels higher than 30%.3- High efficient feed utilization (low values of FCRand high values of FCE) was observed in group fed 30%C.protein than other groups.4- PER decreased with increasing dietary C.protein level.