The effects of varying dietary protein level on the growth,food conversion,protein utilization and body composition of juvenile tilapias (Sarotherodon mossambicus)

The effects of varying dietary protein level on several nutritional parameters of Sarotherodon mossambicus were studied. Eight approximately isoenergetic diets were formulated with protein levels ranging from 0% to 56% in increments of 8%. A zero protein diet was included so that true digestibility, Net Protein Utilization (NPU) and Biological Values (BV) were determined.Specific growth rates (%/day) were: 40% protein (3.85) > 48% protein (3.49), 56% protein (3.51) > 32% protein (3.04), 24% protein (3.10) > 16% protein (2.46) > 8% protein (1.32) > 0% protein (?0.16). Food conversion decreased with increasing dietary protein levels, although not significantly above 40%. Protein efficiency ratio, NPU and BV all decreased with increasing dietary protein level whilst carcass analysis and protein digestibility were little affected. The minimum dietary protein level producing maximum growth of S. mossambicus was found to be 40%, with a dietary protein to energy ratio (P : E) of 116.6 mg protein per kilocalorie of calculated metabolizable energy.