Protein Requirements of Fattening Nile Tilapia (Oreochromis niloticus) Fed Fish Meal-Free Diets

This study aimed to determine the protein requirements of the fattening phase for Nile tilapia (Oreochromis niloticus) fed fish meal-free diets. A total of 75 Nile tilapia were maintained in a water recirculation system, and five isoenergetic diets were formulated with increasing protein levels encompassing three repetitions each. The findings revealed that protein levels significantly affected (p < 0.05) certain Nile tilapia performance, yield, and composition parameters. The determined parameter values clearly indicated that Nile tilapia can be fed fish meal-free soybean meal and corn-based diets. Furthermore, the metabolic plasticity of this species concerning dietary protein concentrations was also demonstrated, with adequate performance results achieved in treatments containing from 267 to 294 g/kg digestible protein (DP), or 298 to 327 g/kg crude protein (CP), where the balance between essential and non-essential amino acids and energy resulted in adequate performance correlated to satisfactory feed conversion values and filet yields and composition. A DP concentration of 267 g/kg (298 g/kg CP) is recommended when offering corn and soybean meal-based diets during the Nile tilapia fattening phase to fish weighing between 400 and 700 g.