Effects of Replacing Soybean Meal with Fermented Bambara Groundnut Meal (Vigna subterranea) Meal in the Diet of Clarias gariepinus Fingerlings

Background: Efforts to reduce fish feed cost have been geared towards fishmeal replacement with cheap ingredients. However, the price of soybean which is a supplementary protein source in fish diet is also soaring due to impact of covid-19 pandemic couple with competition by man and livestock; this therefore calls for a search for its alternatives. Bambara groundnut (BG), although highly nutritious and climate resistant crop, is described as a neglected and under-utilized crop in most countries of Africa. Aims: To ascertain the effect of replacing soybean meal with Fermented Bambara Groundnut Meal (FBGM) on the growth performance and feed utilization of C. gariepinus. Study Design: Completely Randomized Design (CRD) was used with five treatments and three replicates. Diet FBGM00 with no FBGM was used as control. Various replacement levels were designation as FBGM25, FBGM50, FBGM75 and FBMG100 for 25, 50, 75 and 100% respectively. Place and Duration of Study: Department of Fisheries and Aquatic Resources Management, Michael Okpara University of Agriculture, Umudike; Central Labouratory, University of Uyo, Nigeria, between May 2021 and August 2021. Methodology: We fermented Vigna subterranea for 72 hours, air-dried, weighed and oven dried at 60˚C for 24 hours, followed by cooling. Dried flour of FBGM and other ingredients were analyzed for proximate composition used in the formulation of experimental diets. These were milled at 2 mm pellets, sundried and stored at 10 per cent moisture content, in black polythene bags. Diets were fed to one hundred and fifty (150) fingerlings of catfish (C. gariepinus) with mean weight 50±2.35 for 84 days. Growth performance, feed utilization and survival rate parameters were calculated and statistically compared. Results: Physico-chemical parameters fluctuated slightly but were within the optimum range. The highest daily weight gain (85.29±14.46 g) was recorded in FBGM75 while the lowest (68.29±8.49 and 69.86±8.73 g) were recorded in the control diet (FBGM00) and FBGM25 respectively. The specific growth rate, daily weight gain, feed conversion ratio, protein efficiency ratio and percentage survival rate also followed the same pattern. However, no significant differences (P>.05) were detected in all these parameters. Conclusion: Fermented Bambara Groundnut Meal can totally replace soybean meal in the diet of C. gariepinus, without adversely affecting growth performance, feed utilization and survival rate. However, the optimum replacement level lies in FBGN75. More researches are needed on the adults or grow out stages to unveil its effects on the grow out stage and brooder and different processing methods employed and compared to the best processing method that will be mild enough to increase the nutrient content while removing the phytochemicals.