Apparent digestibility of some protein sources for Nile tilapia (Oreochromis niloticus)

A digestibility trial was carried out to determine the dry matter (MS), gross energy (EB) and crude protein (PB) apparent digestibility coefficients (CD) for fish meal (FP), poultry by-products meal (FV), gluten meal (GM) and alchool spray dried yeast (LV) for Thai Nile tilapia fingerlings. A hundred sexually reverted fishes (average weight 37.6 +/- 5.0 g) were assigned to two 500-L feeding tanks and two 150-L cylindrical tanks with conical bottom, to feces collection. CD analysis was performed by the indirect method, using 0.1% chromic oxide (Cr2O3), as marker. Average water temperature, dissolved oxygen, pH and conductivity were 25.8 +/- 1.0degreesC; 3.2 +/- 1.4 mg/L; 6.8 +/- 0.1; and 205.7 +/- 16.5 muS/cm, respectively. CD of PB, EB and MS were 90.66, 89.53 and 87.63 for FP; 82.03, 72.09 and 62.21 for FV; 97.61, 93.52 and 91.01 for GM; 77.39, 62.77 and 58.68 for LS, respectively. The digestible values of protein (%) and energy (kcal/kg), as fed basis, were 53.01 and 3568.0 for FP; 47.65 and 3650.9 for FV; 65.34 and 5036.7 for GM; and 32.19 and 2706.9 for LS.