Substitution of solid-state fermented bambara nut meal with pigeon pea meal and effects on growth and nutrient utilization of Oreochromis niloticus

There is a boom in aquaculture production in Nigeria but high cost of feed is a serious setback. The use of plant proteins in aqua-feed is a plausible alternative to reduce fish-in fish-out ratio and increase profitability. Bambara nut and pigeon pea are neglected plant proteins with high protein, lysine and methionine contents but have anti-nutritional factors (ANFs). Solid state fermentation can remove these ANFs and spike protein content of the ingredients. Bambara nut (BNM) and pigeon pea (PPM) meals were fermented with Saccharomyces cerevisiae using solid-state techniques. The fermented BNM and PPM were used in formulating novel diets for Oreochromis niloticus. Inclusion levels of FBNM: FPPM were: Feed 1, 250:50; Feed 2, 200:100; Feed 3,150:150; Feed 4, 100:200 and Feed 5, 50:250. There was a sixth diet (commercial fish feed, Feed 6) which served as the control. Nile tilapia of average weight 3.08g were stocked at 12 fish per 20L plastic aquaria and fed for 60 days at 12 hours light and 12 hours darkness regime (12D:12L photoperiod). Growth performances and proximate compositions were estimated using standard procedure. Results showed that specific growth rate (SGR) was highest (2.81±0.06%day-1) for those fish treated with Feed 1 and lowest (1.37±0.01% day-1) in those fed Feed 5. Similar results were obtained in food conversion ratio (FCR) with the best value (1.00±0.01) recorded in Feed 1. The best average weight gain (13.19±0.02g), protein efficiency ratio (0.38±0.07) and daily feed intake (1.56±0.03g day-1) followed similar trend with significant (p < 0.05) variations among treatment groups. The waste production ratio was almost zero for fish fed Feed 1. The results of the present study suggested that all feed groups were well utilized by the fish with Feed 1 out-performing all others. Thus, fermented BNM was better utilized in Nile tilapia than fermented PPM.