ABSTRACT
This study was carried out to evaluate the growth performance and nutrient utilization of African catfish fed toasted velvet beans (Mucuna pruriens) seed meal as a dietary protein source. The Mucuna seeds were prepared and dehulled, then processed using the toasting method according to a standard procedure. The processed M. pruriens seed meal (MSM) was evaluated for proximate composition and included in the fish diet at 0%, 25%, 50%, 75% and 100% (CDT, TDT1, TDT2, TDT3 and TDT4, respectively) replacement of soybean in an indoor experiment for 12 weeks. The fish of average size of 5g were fed at 5% body weight twice daily in a semi-flow-through system. The system was evaluated using the monitoring of selected water quality parameters, temperature, pH, and dissolved oxygen, while the fish were examined for growth and nutrient utilization indices at the end of the 12 weeks. All the data were analysed using one-way analysis of variance, and significance was recorded at P<0.05. The water quality parameters were similar among the treatments except pH, where the control had 6.98, which was significantly lower (P<0.05) than 7.34±0.32 in TDT2 and 7.32±0.34 in TDT4. The highest final weight (45.88±0.58g), mean weight gain (40.68±0.58g), daily growth rate (0.48±0.01g/day) and specific growth rate (1.12±0.05%/day) were recorded in TDT2, and it was significantly different from all other treatments, with the least in TDT4. The highest FCR of 2.00±0.10 was observed in TDT4, while the lowest, 1.33±0.01 was in CDT. The highest protein efficiency ratio, 2.45±0.05 was observed in TDT2, and it was significantly different from all other treatments. Survival was not significantly different (P>0.05) among CDT, TDT1 and TDT2. The total fish production was also similar between CDT (3.47±0.11kg/m3) and TDT1 (3.42±.0.08kg/m3). The study revealed that toasted mucuna seed meal-based diet can effectively replace soybean up to 75% with 50% as the optimum inclusion level. Therefore, the use of toasted Mucuna seed meal is hereby recommended as a replacement of soybean meal up to 50% in the diet of African catfish juveniles.
Keywords: African catfish, growth performance, seed meal, toasted mucuna