Multi‐species probiotics enhance growth of Nile tilapia ( <i>Oreochromis niloticus</i> ) through upgrading gut, liver and muscle health

Abstract

The application of probiotics in aquaculture is growing due to its consistently beneficial results as an ecologically sound agent. A study was done in the laboratory using multi-species probiotics containing Bacillus spp. (1 × 109 cfu/ml) and Lactobacillus spp. (1 × 1011 cfu/ml) to assess the growth performance of Nile tilapia (Oreochromis niloticus). Tilapia fingerlings (5.95 ± 0.07 g) were stocked and evenly distributed into three replicates separated into three treatment groups, each providing probiotics at concentrations of 0, 0.5 and 1.0 ml/L in water for 8 weeks. After completion of the trial, growth factors (weight gain, specific growth rate, hepato-somatic index and viscera somatic index), feed utilization parameter (feed conversion ratio), gut microbiota and intestinal, liver and muscle morphology were examined. The experiment revealed significant improvements in growth and feed utilization in the fish reared with multi-species probiotics compared to the control group. Total viable count (TVC) and total lactic acid bacteria (LAB) count increased substantially in the fish gut provided with the multi-species probiotics. The morphological improvement of the intestine includes increased intestinal length, width and area of the villi, lamina propria and abundance of goblet cells were observed in the probiotics-treated fish. The livers of treated fish showed irregular-shaped nuclei turned into regular shaped and reduced spaces between liver tissues. Increased number of nuclei, the diameter of muscle fibre and hyperplastic muscle fibre were also found from morphological observation of the multi-species probiotics applied to fish compared with the control group. The study indicates administration of multi-species probiotics can potentially serve as an important growth promoter for the Nile tilapia.