Valorized Palm Kernel Cake and Bambaranut Meal Affects Amino Acids, Growth and Nutrient Utilization in African Catfish, <i>Clarias gariepinus</i>

Abstract

The high cost of fishmeal and plant protein like soybean has necessitated the search for alternative aqua feed ingredients like proteinous agro waste products. Agro waste are cheap and plausible alternative but lacks some essential amino acids and has several anti-nutritional factors (ANF) like phytic acid, non-starch polysaccharides, high fiber, and protease inhibitors. Solid-state fermentation of the agro wastes can reduce the ANF and improve the protein and nutritional values of feed ingredients. Palm kernel cake (PKC) is a byproduct of palm kernel oil production, and it is proteinous and abundant in Nigeria. Bambaranut meal (BNM) is a neglected proteinous legume high in methionine and lysine and is abundant and cheap. Freshly produced PKC and BNM were solid-state fermented for 5 days in a bioreactor using Saccharomyces cerevisiae and used to produce five novel diets. The inclusion levels of solid-state fermented PKC: BNM per diet were as follows: F1, 450:50, F2,350:150, F3,250:250, F4,150:350, and F5,50:450. There was a control diet labeled as feed F6 which was a control. A total of 270 African catfish fingerlings of average weights distributed as follows F1, 2.63±0.06g, F2, 2.70±0.13g, F3, 2.40±0.08g, F4, 2.30±0.05g and F5, 2.70±0.09g, were acclimatized for 7 days and stocked at 15 fish per 3 replicates aquaria per treatment feed. The catfish were fed ad libitum two times daily with the treatment feeds for 70 days. Culture water was changed daily. Catfish were weighed every 14 days. The catfish that received feed F4 (PKC:BNM;150:350g) had the best specific growth rate (SGR) of 4.43±0.06% day-1, lowest food conversion ratio (FCR) of 1.01±0.07 and highest protein efficiency ratio (PER) of 1.24. The catfish fed feed F3 (PKC: BNM) 250:250g, was next to F4 with SGR, Final weight, gut volume, and gut weight were all higher for catfish receiving feed F4 followed by those fed feed F2. There were no significant differences between the PER of catfish-fed diets F2, 0.39±0.03 and F3, 0.39±0.06. The lysine and methionine content of the feed increased with inclusion of FBNM than FPKC. In conclusion, solid state fermented BNM and PKC should be included in catfish feed for optimal growth and profitability.