Investigation of using of poultry by-product meal replacement commerical fish meal in Tilapia Oreochromis niloticus L., fry

In this study, the possibility of replacing commercial fish meal with poultry by-product meal (PBM) in diets for Nile tilapia fry, Oreochromis niloticus was investigated. Eight isonitrogenous diets were formulated to contain 34% protein, 9% lipid and 3500 DE kcal/g. Fish meal was replaced by 0% control group, 25%, 50%, 75% and 100% of PBM. The control diet contained fish meal (40.8%) and soybean meal (19.65%) as the main sources of dietary protein. Tilapia fry were reared in 65 L class aquaria maintained in stagnant water. Each dietary treatment was tested in triplicate groups of 20 fish per aquarium in a completely randomized design. Fish with average weight of 0.879±0.09 g were fed the diets twice per daily to apparent satiation for 13 weeks. In the experiment, diets were evaluated based on growth performance, diet utilization, body composition and digestibility. Results demonstrated that fish growth increased with increasing PBM up to 50%, which produced the highest growth of the treatments. The lowest fish growth was obtained at 75 and 100% PBM. Survival was similar for all dietary treatments (100%). Hepatosomatic index (HSI) and visscero somatic index (VSI) among all groups at the end of the experiment were not significantly affected by the dietary treatments (P>0.05), but the highest HSI (2,720±0,394) and VSI (2,720±0,394) values were recorded in fish fed with 50% PBM diet. There was no significant difference in whole body composition (moisture, lipid, protein and ash) for all experimental groups (P>0.05), except for initial fish composition (P<0.05). Protein, lipid and energy digestibility coefficients of the diets decreased with increasing dietary PBM, were significant differences among dietary treatments (P<0.05), and ranged from 64.2-72.3%, 75.3-81.4% and 80.4-85.7%, respectively. High values for digestibility were observed in fish fed with 50% PBM diet. However, dry matter digestibility coefficient was no significant differences among dietary treatments. The results showed that up to 50% of fishmeal protein can be replaced by PBM with no adverse effects on growth, feed utilization, body composition and digestibility of Nile tilapia fry.KEY WORDS: Oreochromis niloticus, fishmeal replacement, poultry by-product meal, growth, digestibility.