Dietary effect of Lactobacillus plantarum (TISTR 912) on digestive enzyme activity, growth performance, immune response, and disease resistance of black sharkminnow (Labeo chrysophekadion) against Aeromonas hydrophila infection

This study investigated the influences of dietary supplementation of Lactobacillus plantarum (LP) on the digestive efficiency, growth performance, immunological response, and disease resistance of black sharkminnow (Labeo chrysophekadion) challenged with Aeromonas hydrophila (A. hydrophila). The fish (2.2 +/- 0.14 g) were fed different doses of LP supplementation (0, 107, 108, and 109 CFU g-1) for eight weeks. The findings indicated that the digestive efficiency of fish fed various dietary LP levels increased significantly after both four and eight weeks of feeding (P < 0.05). The growth parameters of fish fed the 108 CFU g-1 LP diet were considerably greater (average of 1.3-fold) than those fed the control diet. All dietary treatments of LP supplementation substantially elevated lysozyme and peroxidase activities in both serum and skin mucus of the black sharkminnow compared to the activities of the control fish (P < 0.05). The highest level of digestive efficiency (1.71-fold), growth rate (1.3 -fold), and immune response was obtained in fish fed the 108 CFU g-1 LP diet (P < 0.05) after four and eight weeks of the trial. Fish that consumed the non-LP dietary supplementation challenged with A. hydrophila had a survival rate of 30%, compared to a survival rate of 73.33-83.33% for those fed the LP dietary supplementations. Collectively, these findings suggest that dietary supplementation with L. plantarum at a concentration of 108 CFU g-1 in the black sharkminnow significantly improved growth rate, digestive enzyme activity, immunity, and disease resistance against A. hydrophila infection. However, the higher dose of L. plantarum (109 CFU g-1) in this study did not significantly improve the studied parameters. The findings suggested that L. plantarum can be potentially used as a functional feed additive in the black sharkminnow culture.