Title: Effect of replacing marine protein with hydrolyzed feather meal on gowth, apparent digestibility and body composition of juvenile tilapias (Oreochromis mossabicus)

This study was conducted to determine the effect of hydrolyzed feather meal on growth, apparent digestibility and body composition of tilapia Oreochromis mossambicus. Five hundred fish were distributed in a completely randomized design with five treatments in quadruplicates with 25 fish (average weight 3.42±1.02g) per tank. The fish were fed isoproteinous diet with increasing inclusion levels of hydrolyzed feather meal (HFM) (0%, 4%, 8% 10% and 12%) designated as HFM0, HFM4, HFM8, HFM10 and HFM12 respectively. Fish fed the diet containing 10% and 12% HFM exhibited a significantly higher growth and nutritional parameters (P<0.05) in terms of mean final weight (8.05± 2.56 and), specific growth rate (3.67±0.29 g), food conversion ratio (1.97±0.11 g) and mean weight gain (4.9±0.33), compared to the other diets. Final body composition was influenced significantly by increasing the level of HFM through decreasing carcass moisture and lipids. Diet containing 12% HFM had significantly lower protein (11.75±0.05%) and ash (8.43±0.51) compared to diet HFM0. Inclusion levels of HFM also improved digestibility and degree of hydrolysis. The diet recommended for O. mossambicus in this study is HFM10.