Effects of palm oil mill effluent sludge and sesame seed meal on growth and gut microbial communities of Clarias gariepinus juveniles

Abstract

High cost of fish feed and poor nutrition are the major setbacks in catfish culture. Fish oil enhances feed acceptance, organoleptic qualities and growth of fish. Thus, the combination of different lipids can increase growth and oxidative stability of fish.This study evaluated effects of palm oil meal effluent sludge and sesame seed meal on growth and gut microbiome of the African catfish, Clarias gariepinus.  Five feeds were produced to vary in the inclusion levels of palm oil effluent sludge (POME) and sesame seed oil meal (SSM) in the following ratio: F1 (POME:SSM 400:0g), F2 (POME:SSM 300:100g), F3 (POME:SSM 200:200g), F4 (POME:SSM 100:300g) and F5 (POME:SSM 0:400g). Other ingredients were added at same levels while a sixth diet (commercial catfish feed) served as the control. African catfish of average initial weight of 10.7-14.2g were stocked at 15 fish per treatment with each treatment replicated three times and fed both the experimental and control diets for 90days. The fish were fed ad libitum. Determination of bacterial loads in fish parts were done using standard microbiological procedures while standard formulae were used to calculate various growth parameters. Results revealed that inclusion of POME and SSM in the diets of juvenile catfish had profound effects on the growth and food conversion ratio. Fish treated with F1 gave the best performance in terms of specific growth rate (SGR; 3.68±0.07%day-1 ) and food conversion ratio (FCR; 1.54±0.01). The gut morphology of the catfish showed that catfish fed F2 (300gPOME:100gSSM), had the highest gut weight (1.25±0.01g) and longest intestinal length (19.93±0.05mm) than catfish fed all other feeds (p<0.05).The catfish fed with F1 had dominant microbial communities of Gram -ve rod including Enterobacter sp. and Escherichia coli. Those fed F2 (POME:SSM 300g100g), had Gram +ve, non-spore forming anaerobic rod, Lactobacillus sp as dominant species while those feed F5 (POME:SSM0g:400g) had Gram-ve rod, Klebsiella sp as part of the dominant species. The outcome of the present study support the inclusion of more of palm oil mill wastes in fish feed formulation.