Protein digestibility status of locally available feed ingredients fed to Nile tilapia (Oreochromis niloticus) in the hatchery, Sebeta, Ethiopia

The nutritional value of a feedstuff isn’t only on its chemical composition, however, the content of the nutrients absorb by the aid of the fish. Thus, this study was developed to determine crude protein digestibility status of the five feeds (noug cake (NK), wheat bran (WB), soybean meal (SM), brewery waste (BW), and fish meal (FM) in Oreochromis niloticus. The experiment was conducted using 180 Oreochromis niloticus population with weight of 28.2 to 28.4 g, distributed in experimental randomized blocks design with five treatments and three replicates per treatment. Digestibility was estimated by the indirect method using chromic oxide at the concentration of 0.50 % of the diet as a marker. The apparent and true digestibility of the protein was estimated for noug cake, 87.1 and 89.1 %; wheat bran 74.3 and 78.7 %; soybean meal 88.3 and 90.0 %; brewery waste 65.4 and 67.8 %; fish meal 85.5 and 87.0 %, respectively in siphoning technique. Similar (P > 0.05) results were observed in striping and siphoning methods in all experimental ingredients. Soybean, noug cake and fish meal had better (P < 0.05) crude protein digestible by Oreochromis niloticus than wheat bran and brewery waste. Brewery waste was the lowest digestible by O. niloticus. The growth performance of the fish also in line with the crude protein digestibility status of the ingredient hence, the lowest growth performance was recorded in fish consumed brewery waste. This indicates, brewery waste isn’t well digestible by O. niloticus.