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The study was conducted to investigate the optimum dietary protein level needed for growing genetically male tilapia, Oreochromis niloticus. Diets containing crude protein levels 40, 42.5, 45, 47.5 and 50% were formulated and tried in triplicates. Test diets were fed to 20 fish/1m3 floating hapa at 5% of fish body weight daily for 24 weeks. Survival of fish was not affected by dietary protein levels. Growth rate varied inversely with dietary protein levels to a maximum at 40%. Protein utilization and turnover decreased with increasing protein levels in diets. Quadratic regression analysis of growth indices against protein inclusion levels indicated that the optimum dietary protein required for maximum growth was 40%.This result also paralleled the least values of protein and calorie deposited for 40% protein level whereas the other levels were significantly (p<0.05) higher. The study concludes that 47.5% and 50% protein levels may depress tilapia growth and feed utilization, while 40% protein gave optimum growth.
Keywords: Genetically male tilapia, Dietary protein levels, Growth, Protein requirement