The use of live microbes as probiotics in improving the health and wellbeing of humans and animals have been extensively studied however the use of those isolated from food products in aquaculture especially fry production is limited in the literature. Lactobacillus fermentum strains BCS27 and F4S8 isolated from fermented food products were included in a basal diet at a concentration of 3x109, 6x106 and 9x103CFU/ml/100g of feed respectively. The concentrations were presented as L1T1, L1T2, L1T3 for BCS27 and L2T1, L2T2, L2T3 for F4S8. At the same time, positive and negative controls contained no bacteria isolate and oxytetracycline at 100mg/kg of feed, respectively. These feeds were fed to 3 days old Clarias gariepinus larvae for six weeks. A pathogenic Aeromonas hydrophila was used to challenge the six weeks old fry and monitored for 2weeks. The survival rate was significantly higher (above 65%) in all the treatments compared with the positive control (42%), see Figs 1 and 2.
A. hydrophila. Bars with the same alphabet are not significantly different at p<0.05
The oxidative stress assay showed increased activity of Superoxide dismutase (SOD), Glutathione Peroxidase (GPx), Glutathione (GSH) and increased Total Protein in the frys fed L. fermentum strains compared with the positive and negative control. The controls had higher activity in Malondialdehyde (MDA) and Nitric Oxide (NO) but was not significantly different (p<0.05) from all the other treatments. It could be concluded that L. fermentum strains BCS27 and F4S8 isolated from fermented food product could improve the antioxidant activity, disease resistance and survival of C. gariepinus fry.
Keywords; Fry, Antioxidants, Lactobacillus fermentum,