Synbiotic Effects of Aspergillus oryzae and β-Glucan on Growth and Oxidative and Immune Responses of Nile Tilapia, Oreochromis niloticus.

Probiotic, prebiotic, and synbiotic application have got considerable attention in aquaculture as a functional feed additive. This trial was considered to assess the synbiotic potential of Aspergillus oryzae (ASP) and β-glucan (BG) on growth, antioxidant status, and immunomodulation of Nile tilapia. For 60 days fish fed the control, or three diets incorporated with 1 ASP, 1 BG, or 0.5 ASP + 0.5 BG g kg-1 (control, ASP, BG, and ASP/BG diets). After final sampling, fish fed ASP, BG, or ASP/BG diets exhibited significant (P < 0.05) increase in the growth and feed efficiency (FBW, WG, SGR, FER, and PER). Modulation of blood hematocrit, hemoglobin, RBC, WBC, total protein, and digestive enzymes was also recorded in the ASP, BG, or ASP/BG diets with the peak presence in the synbiotic group. However, decreased blood triglyceride was reported in fish fed ASP or ASP/BG diets. A significant (P < 0.05) elevation in villi length was observed by dietary supplementation of synbiotic over the other regimes. Further, ASP or synbiotic additives effectively elevated the activity of antioxidative enzymes (SOD and CAT), while GPX enhanced in ASP, BG, or ASP/BG groups. But, the oxidative enzyme (MDA) decreased in ASP or ASP/BG groups compared to the other groups. ASP or ASP/BG supplementation enhanced NBT, IgM, lysozyme, bactericidal, and phagocytosis which indicated improved immunity of tilapia by synbiotic additives. Accordingly, the use of synbiotic is an efficient approach to reach economically feasible and sustainable tilapia production.