Growth performance and sensory parameters of african catfish (Clarias gariepinus) fed with a sublethal dose of neem leaf extract, and its antibacterial effects

Abstract

The antibacterial effects of Neem leaf, the growth performance and sensory qualities of African catfish fed with Neem leaf inclusion were investigated in this study. Ninety (90) post-juvenile Clarias gariepinus (42.40 ± 2.50 g) were used. Experimental groups in triplicate were exposed bi-weekly to 3.5% and 7% LC50 of Neem leaves aqueous extract infused in commercial floating feed for four weeks, while the control group was exposed to untreated feed. The whole body length and weight of randomly sampled fish were taken for organo-somatic indices. Gills and skin samples were collected for bacteriological screening, while fish muscles were prepared for sensory acceptability tests. Mean feed intake was significantly (P<0.05) influenced by Neem leaf in the three treatment concentrations with an insignificant difference between the treated groups, but it was higher than in the control group. Mean weight gain was significantly higher (P<0.05) in the Neem fed fish than the control but insignificant the differences between treatment doses were insignificant, while the feed conversion ratio was significantly lower (P<0.05) in the Neem fed groups compared to the control, but the difference was insignificant between the treatment doses. All groups were apparently healthy looking with 100% survival. There was a considerable reduction in total bacterial count in both the gills and skin with the increase in Neem concentration. Micrococci spp. and Bacillus subtilis were not isolated in the gills but were present in the skin, while E. coli and Pseudomonas fluorescens were not suppressed in the skin. There was no significant difference (P<0.05) in all the sensory parameters across all groups. The inclusion of Neem leaf extract was shown to have a high antibacterial effect coupled with excellent growth performance and general acceptability of fish tissue.