Feed efficiency, hematological parameters, and resistance against Streptococcus agalactiae of Nile tilapia (Oreochromis niloticus) as improved by dietary supplementation of Lactobacillus plantarum L03

The utilization of beneficial bacteria in aquaculture is increasingly advocated due to their positive impact on fish growth and health. This study assesses the effect of dietary Lactobacillus plantarum L03 on the growth and disease resistance of Nile tilapia Oreochromis niloticus. Fish (19.07 +/- 0.43 g) were fed with a diet supplemented with L. plantarum at 0, 2, 5, 10 g/kg (referred to as LP0, LP2, LP5, and LP10 treatments) for seven weeks. One day after the end of experiment, fish were infected with Streptococcus algalactiae at 5 x 10(5) CFU/mL and monitored for 14 days. Blood samples were collected for hematological analyses after feeding trial and bacterial challenge. The results indicated no effects of dietary L. plantarum on fish growth, while the positive effects on feed conversion ratio and protein efficiency ratio (P < .05) were found in LP2 and LP5-fed fish. The supplementation of probiotics exhibited beneficial effects on red and white blood cells, hemoglobin, hematocrit, and mortality after bacterial challenge for LP5 treatment (P < .05). In conclusion, LP5 treatment at a dietary supplementation of 5 g L. plantarum per kg resulted in positive outcomes on feed utilization, cellular immunity, and disease resistance in Nile tilapia.