Replacement of Fish Meal with Bambara Nut Waste Meal in the Diets of Larval African Catfish Clarias gariepinus Burchell (1822)

Background: High cost of fishmeal (FM) adversely affects growth performance of African catfish fingerlings. There is need for alternative ingredients from affordable and available sources like plant proteins to meet growing feed demands in the larviculture of African catfish. Bambara nut waste meal (BNWM) is a proteinous, cheap and abundant, byproduct usually discarded or used to feed domestic chicken in Africa.
Aims: To substitute fishmeal (FM) with bambara nut waste meal (BNWM) in five novel diet of larval African catfish Clarias gariepinus average weight 1.850±0.79 g and examine their growth and nutritional performances.
Place and Duration: The experiment was carried out at the Fisheries and Hybrobiology, research unit department of Zoology University of Nigeria Nsukka between Nov.29 and 30 of December.
Methodology: We substituted BNWM:FM per diet as follows; feed 1, (F1), 94:0%; feed 2, (F2), 89:5%; feed 3, (F3), 74:20%; feed 4, (F4), 59:35%; and feed 5, (F5), 39:55%. Other ingredients were vitamin premix, vitamin C and palm oil. Catfish larvae of average weight 1.850±0.79, stocked at 15 larvae aquarium-1 were fed with the experimental diets (F1-F5) for 30d.
Results: African catfish larvae grew with optimal SGR of 8.2% day-1 for those fed with 39BNWM:55FM, F5 and 7.2% day-1 for those fed with 59BNWM:35FM, F4. The catfish fed with F1 94BNWM:0FM, and F2, 89BNWM:5FM, had lowest but similar SGR 5.0 and 5.3% day-1 respectively. Food conversion ratio (FCR) were similar for larvae fed with F5, F4 and F3 (P>0.05). Similarly FCR were similar for larvae fed with F1 and F2 (P>0.05). The weight gains of the larvae were best and similar for those fed 39BNWM:55FM, F5 (5.0 g) and F4 59BNWM:35FM, (4.5 g), but better than those fed 74BNWM:20FM, F3 (3.5 g). Those fed with F1 had least weight gain of (2.2 g). The protein efficiency ratio (PER) increased with FM inclusion but similar for catfish fed F5 6.78±0.02 and F4 6.33±0.05. The catfish PER was lowest for those fed all plant protein diet F1 94BNWM:0FM, PER, 3.97±0.04..3. Cost of feed increased with FM inclusion and fishmeal ratio (FMR) was highest for F5.
Conclusion: The study shows that BNWM can supplement FM up to 59% in diets of African catfish. The lack of significant differences between FCR and SGR of catfish fed 39BNWM:55FM, F5 and F4 59BNWM:35FM is indicative of cost saving and benefits of BNWM. It shows that BNWM which is discarded in mills is a valuable resource that holds profitable potential in aquafeed production.