Inclusion of Pediococcus acidilactici as probiotic candidate in diets for beluga (Huso huso) modifies biochemical parameters and improves immune functions.

Administration of probiotic candidates in fish has generally been shown as a useful strategy to improve growth performance, survival, digestive enzyme activity, and gut microbiota. Unfortunately, the sero-immunological responses of different fish to different probiotic candidates are poorly understood. The present study assessed the effect of Pediococcus acidilactici as a probiotic on the biochemical and immunological parameters of beluga. Fish (248.32 ± 10.21 g) were fed a control diet (without P. acidilactici( and three different doses of P. acidilactici-supplemented diets (107, 108, and 109 CFUg-1 diets) for 8 weeks. On week 8, blood and serum were sampled. Dose-dependent increase of immunological parameters (respiratory burst activity, lysozyme content, serum antibacterial activity, and total immunoglobulin) and biochemical parameters (total protein and albumin levels) was observed. However, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were significantly increased in the juvenile beluga fed by 109 CFUg-1 P. acidilactici-supplemented diet compared to the other groups. Based on the results of this evaluation, it is reasonable to conclude that the inclusion of P. acidilactici as probiotic in diets for juvenile beluga improves the sero-immunological parameters of the fish and should be considered by farmers as a strategy to improve fish health.

Dietary galactooligosaccharide affects intestinal microbiota, stress resistance, and performance of Caspian roach (Rutilus rutilus) fry.

The aim of this study was to assess the effects of galactooligosaccharide (GOS), on the growth performance, stress resistance and intestinal microbiota of Caspian roach (Rutilus rutilus) fry. Specimens (1.36 ± 0.03 g) were fed either a basal control diet (0% GOS, non-supplemented) or the basal diet supplemented with 1% and 2% of GOS. After 7 weeks of the feeding trials, growth factors (final weight, weight gain, specific growth rate, condition factor and food conversion ratio) as well as body composition, resistance to salinity stress and autochthonous intestinal microbiota were assessed. Results demonstrated that at the end of the trial growth factors (final weight, weight gain, SGR, FCR) were significantly higher in 2% GOS fed fish (P < 0.05). In addition, supplementation of GOS significantly increased both survival rate (P < 0.05), and resistance to a salinity stress challenge of prebiotic fed groups (P < 0.05). However, body composition and the total autochthonous intestinal heterotrophic bacteria counts remained unaffected in different treatments (P > 0.05). Nevertheless, autochthonous lactic acid bacteria levels were significantly elevated in fish fed 2% dietary GOS (P < 0.05). These results confirm that GOS improves growth performance, stress resistance and modulates intestinal microbiota by increasing lactic acid bacteria of Caspian roach fry, a very important fish species in the Caspian Sea.

Effect of dietary supplementation of fructooligosaccharide (FOS) on growth performance, survival, lactobacillus bacterial population and hemato-immunological parameters of stellate sturgeon (Acipenser stellatus) juvenile.

The dietary supplementation of fructooligosaccharide (FOS) in stellate sturgeon juvenile, Acipenser stellatus (with mean initial body weight of 30.16 ± 0.14 g) was evaluated for the effect on growth, autochthonous intestinal microbiata and hemato-immunological parameters for 11 weeks. FOS was added at a level of 0, 1% and 2% to the commercial pellet diet (BioMar). At the end of the experiment, growth parameters, survival rate, lactobacillus bacterial population, hematological and immunological parameters were determined. The fish fed on 1% FOS significantly showed higher final weight, WG%, SGR and PER and lower FCR compared to those of the control group (P < 0.05). Survival rate did not significantly differ between the treatments (P > 0.05). However, FOS administration resulted in lower survival. The serum lysozyme activity was significantly affected by dietary 1% FOS (P < 0.05), while respiratory burst activity was not significantly affected by dietary treatments (P > 0.05). In fish fed on the diet with 1% FOS showed a significant increase of total heterotrophic autochthonous bacterial and presumptive LAB levels (P < 0.05) compared with those fed on the diets supplemented with prebiotics. In addition to increase in WBC, RBC, MCV, hematocrit, hemoglobin and lymphocyte levels were observed in this group. These results indicated that dietary supplementation of FOS at a dose of 1% improved growth performance, beneficial intestinal microbiata and stimulate immune response of stellate sturgeon juvenile.