Use of symbiotics in biofloc (BFT)-based Nile tilapia culture: Production performance, intestinal morphometry and hematological parameters

Symbiotics are a combination of prebiotics and probiotics that positively affect the animal by stimulating health-promoting bacteria and thus improving production performance and animal welfare. The aim of this study was to evaluate a water symbiotic on the performance, hematological parameters and intestinal morphometry of Nile tilapia raised in a biofloc technology system (BFT) for the initial grow-out phase. Eighty juveniles (initial weight: 30–35 g) were stocked in eight 100-L tanks (10 fish/box). The fish were evaluated using BFT with and without symbiotics. The symbiotic was added directly to the water on a weekly basis at a dose of 0.2 mg L−1 (commercial recommendation for the product). The experiment was laid out in a completely randomized design with two treatments (BFT with symbiotics and BFT without symbiotics) and four replicates, totaling eight experimental units. The experimental period was 40 days. Final weight, weight gain and the specific growth rate were higher (p < .05) in the fish produced in BFT with symbiotics (77.28 ± 0.61 g; 46.79 ± 0.64 g; 2.33 ± 0.03%) than in those farmed in BFT without symbiotics (73.31 ± 0.73 g; 42.54 ± 0.77 g; 2.17 ± 0.04%). Feed conversion ratio was higher (p < .05) in the group reared in BFT without symbiotic (1.02 ± 0.01) as compared with those farmed in BFT with symbiotics (0.94 ± 0.01). Overall, hematological conditions were better (p < .05) in the fish grown in BFT with symbiotics. There were no major differences in intestinal morphometry between treatments. The inclusion of symbiotics in BFT improved the performance and hematological parameters of Nile tilapia in the initial phase (30 to 77 g) without causing significant changes in intestinal morphometry or intestinal cell density.