Abstract:
This study was carried out to determine the utilization of different portions of cassava root as energy sources in the diet of Oreochromis niloticus. The experimental fish were distributed randomly in a completely randomized design (CRD) into 15 rectangular glass tanks (60 x 35 x 30 cm3) at a density of 20 fish per tank representing five dietary treatments. Fish were fed with dietary treatment at 3% of their body weight per day in two equal meals at 0800-1000 and1700 -1800 Hr. The diets were designated as control, peel, tuber, starch, and chaff respectively.Water quality parameters, haematological analysis, growth performance and proximate analysis were determined using standard methods. Data collected on proximate composition, mineral, growth performance, nutrient utilization and haematological parameters were analysed by One-Way Analysis of variance. Results showed that the lowest (0.42±0.07) crude protein was recorded in cassava chaff while the peel portion of the cassava had the best (6.84±0.01) crude protein. Calcium content ranged from 27.22 mg 100-1 -170.30 mg 100-1 and highest in cassava peel. Haematological parameters indicated that there were no significant differences (P< 0.05) between the blood Pack Cell Volume of fish fed with peel and cassava chaff. However, Pack Cell Volume of fish fed diet containing starch was significantly different (P<0.05) from other experimental diets. Statistical analysis further revealed that Red Blood Cell, White Blood Cell, leucocytes and neutrophils showed significant differences (P< 0.05) in O. niloticus fed the experimental diets. The highest Specific growth rate (0.46 %/d) was recorded in fish fed control diet while the lowest (0.30 ± 0.01) was observed in fish fed diet containing cassava tuber. Fish in the control diet had the highest weight gain (2.44 ± 0.67) while the lowest weight gain was recorded in O. niloticus fed diet containing cassava tuber. Cassava peel had the highest (383.64±10.12kcal/kg) gross energy while cassava tuber had the least gross energy (151.06±5.35 kcal/kg).
Based on the results obtained in this study, inclusion of different portions of sweet cassava root (Manihot palmata) in the diet of Oreochromis niloticus compared favorably with that control diet containing maize in its growth and survivability. Tilapia fed cassava peel diet had the best weight gain among fish fed experimental diets and this could be attributed to its gross energy component, acceptability and utilization by the fish. Fish farmers can take advantage of this ingredient (cassava peels) as a replacement for more expensive maize when formulating feed for tilapia in culture.
