Effects of Jerusalem Artichoke (Helianthus tuberosus) as a Prebiotic Supplement in the Diet of Red Tilapia (Oreochromis spp.).

The aim of the present study was to evaluate the effects of a Jerusalem artichoke-supplemented diet on the blood chemistry, growth performance, intestinal morphology, expression of antioxidant-related genes, and disease resistance against Aeromonas veronii challenge in juvenile red tilapia. A completely randomized design (CRD) was followed to feed red tilapias with three experimental diets: control, 5.0 g/kg JA-supplemented (JA5), or 10.0 g/kg JA-supplemented (JA10) diets in triplicates for 4 weeks. The results revealed that the growth performance, weight gain (WG), specific growth rate (SGR), and average daily gain (ADG) of fish fed diets JA5 and JA10 were significantly higher (p < 0.05) than those of fish fed the control diet. Fish fed the control diet had significantly higher T-bilirubin, D-bilirubin, and ALT in blood serum than fish fed JA5 and JA10, as well as higher BUN than fish fed JA5. The number of goblet cells in the proximal and distal parts of the intestine revealed that the number of acid, neutral, and double-staining mucous cells of fish fed diets JA5 and JA10 was significantly higher (p < 0.05) than in fish fed the control diet. The diets including the prebiotic (JA5 and JA10) were associated with a significant increase in the expression of gpx1 and gst antioxidant-related genes and disease resistance against A. veronii in juvenile red tilapia. Therefore, JA5 and JA10 can be employed as promising prebiotics for sustainable red tilapia farming.

Modulation of the mucosal immune response of red tilapia (Oreochromis sp.) against columnaris disease using a biomimetic-mucoadhesive nanovaccine.

Columnaris, a highly contagious bacterial disease caused by Flavobacterium columnare, is recognized as one of the most important infectious diseases in farmed tilapia, especially during the fry and fingerling stages of production. The disease is associated with characteristic lesions in the mucosa of affected fish, particularly their skin and gills. Vaccines delivered via the mucosa are therefore of great interest to scientists developing vaccines for this disease. In the present study, we characterized field isolates of F. columnare obtained from clinical columnaris outbreaks in red tilapia to select an isolate to use as a candidate for our vaccine study. This included characterizing its colony morphology, genotype and virulence status. The isolate was incorporated into a mucoadhesive polymer chitosan-complexed nanovaccine (CS-NE), the efficacy of which was determined by experimentally infecting red tilapia that had been vaccinated with the nanoparticles by immersion. The experimental infection was performed 30-days post-vaccination (dpv), which resulted in 89% of the unvaccinated control fish dying, while the relative percentage survival (RPS) of the CS-NE vaccinated group was 78%. Histology of the mucosal associated lymphoid tissue (MALT) showed a significantly higher presence of leucocytes and a greater antigen uptake by the mucosal epithelium in CS-NE vaccinated fish compared to control fish and whole cell vaccinated fish, respectively, and there was statistically significant up-regulation of IgT, IgM, TNF α, IL1-ß and MHC-1 genes in the gill of the CS-NE vaccinated group. Overall, the results of our study confirmed that the CS-NE particles achieved better adsorption onto the mucosal surfaces of the fish, elicited great vaccine efficacy and modulated the MALT immune response better than the conventional whole cell-killed vaccine, demonstrating the feasibility of the mucoadhesive nano-immersion vaccine as an effective delivery system for the induction of a mucosal immune response against columnaris disease in tilapia.

Efficacy of synbiotic Jerusalem artichoke and Lactobacillus rhamnosus GG-supplemented diets on growth performance, serum biochemical parameters, intestinal morphology, immune parameters and protection against Aeromonas veronii in juvenile red tilapia (Oreochromis spp.).

Synbiotics, a synergistic combination of probiotics and prebiotics, are currently regarded as one of the most practical nutritional supplements in tilapia farms. In this study, the effect of supplementing the diet of red tilapia (Oreochromis spp.) with Jerusalem artichoke (Helianthus tuberosus) and Lactobacillus rhamnosus GG (LGG) was evaluated. Growth performance, serum biochemical parameters, intestinal morphology, goblet cell counts, immune parameters and protection against Aeromonas veronii challenge were determined. The results showed that fish fed with synbiotic-supplemented diets had a significantly higher (P < 0.05) feed conversion ratio (FCR), specific growth rate (SGR), and average daily gain (ADG) than fish fed with a control diet. The synbiotic-supplemented diet increased glucose, total protein and the total cholesterol levels. The absorptive area of the proximal and distal intestine of fish fed on the synbiotic diet was significantly higher (P < 0.05) than in those fed with probiotics (LGG), prebiotic-supplemented diets (JA), and the control diet. Goblet cell counts revealed that the numbers of acid mucous cells, neutral mucous cells and double-staining mucous cells of fish fed the synbiotic-supplemented diet (JA + LGG) were significantly higher (P < 0.05) in the proximal and distal intestine. Fish fed the synbiotic-supplemented diets also exhibited significantly higher (P < 0.05) lysozyme activity. The cumulative mortalities of fish fed with a synbiotic-supplemented diet were significantly lower than those of fish fed other diets. The results suggested the beneficial effect of JA and LGG synbiotic diet on growth performance and health status of red tilapia. Direct administration of JA and LGG in fish feed can be used as a practical nutritional supplement in red tilapia.