Evaluation of Two Different Dietary Synbiotics on Growth Performances, Hematological Parameters and Non-Specific Immune Responses of Juvenile Nile Tilapia (Oreochromis niloticus)

Abstract

The aim of the current study was to evaluate the effects of two different dietary synbiotics; Bacillus subtilis with mannan oligosaccharides and Enterococcus faecium with fructo oligosaccharides on growth performances, hematological parameters and non-specific immune responses in juvenile Nile tilapia (Oreochromis niloticus). Six experimental diets include a basal diet (CON), a positive control diet (OTC) with antibiotics (0.4% oxytetracycline of diet) and 4 synbiotic diets consisting the basal diet with B. subtilis (1×107 or 1×108 CFU·g-1) with 0.4% of mannan oligosaccharide (BS7M or BS8M) and the basal diet with E. faecium (1×106 or 1×107 CFU·g-1) with 0.4% of fructo oligosaccharide (EF6F or EF7F). Eighteen tanks of fish averaging 4.8 ± 0.05 g (mean ± SD) were randomly assigned into six experimental diets with three replicates, and fish fed 6 experimental diets for eight weeks. Average weight gain (WG) of fish fed OTC, BS8M, EF6F and EF7F diet were significantly higher than those of fish fed CON diet (P<0.05). WG of fish fed EF7F diet were significantly higher than those of fish fed BS7M diet although there were no significant differences among fish fed OTC, BS8M, EF6F and EF7F diet. Average specific growth rate (SGR) of fish fed OTC, BS7M, BS8M, EF6F and EF7F diet were significantly higher than those of fish fed CON diet (P<0.05). SGR of fish fed EF7F diet were also significantly higher than those of fish fed BS7M diet although there were no significantly differences among fish fed OTC, BS8M, EF6F and EF7F diets. Feed utilization, organosomatic indices, hematological parameters and non-specific immune responses including myeloperoxidase and lysozyme activity were not significant differences among fish fed 6 experimental diets (P>0.05). Therefore, these results may indicate that the supplementation of two synbiotics in the basal diet; BS7M, BS8M, EF6F and EF7F could be the effective synbiotics and the potential antibiotic replacers in Nile tilapia, Oreochromis niloticus. However, EF7F and BS8M could be better than EF6F and BS7M as the synbiotics and antibiotic replacers in Nile Tilapia, Oreochromis niloticus.