Application of nZnO supported with nanoclay for improving shrimp immunity.

This study discloses the nanoscale silicate platelet-supported nZnO (ZnONSP) applied as novel feed additives in aquaculture. The preparation of the nanohybrid (ZnO/NSP = 15/85, w/w) was characterized by UV-visible spectroscopy, powder X-ray diffraction and transmission electron microscope. The effects of ZnONSP on growth, zinc accumulation, stress response, immunity and resistance to Vibrio alginolyticus in white shrimp (Penaeus vannamei) were \demonstrated. To evaluate the safety of ZnONSP, shrimps (2.0 ± 0.3 g) were fed with ZnONSP containing diets (200, 400 and 800 mg/kg) for 56 days. Dietary ZnONSP did not affect the weight gain, specific growth rate, feed conversion ratio, survival rate, zinc accumulation, and the expression of heat shock protein 70 in tested shrimps. To examine the immunomodulatory effect of ZnONSP, shrimps (16.6 ± 2.4 g) were fed with the same experimental diets for 28 days. Dietary ZnONSP improved the immune responses of haemocyte in tested shrimps, including phagocytic rate, phagocytic index, respiratory burst, and phenoloxidase activity, and upregulated the expression of several genes, including lipopolysaccharide, ß-1,3-glucan binding protein, peroxinectin, penaeidin 2/3/4, lysozyme, crustin, anti-lipopolysaccharide factor, superoxide dismutase, glutathione peroxidase, clotting protein and α-2-macroglobulin. In the challenge experiment, shrimps (17.2 ± 1.8 g) were fed with ZnONSP containing diets (400 and 800 mg/kg) for 7 days and then infected with Vibrio alginolyticus. Notably, white shrimps that received ZnONSP (800 mg/kg) showed significantly improved Vibrio resistance, with a survival rate of 71.4 % at the end of 7-day observation. In conclusion, this study discovers that ZnONSP is a new type of immunomodulatory supplement that are effective on enhancing innate cellular and humoral immunities, and disease resistance in white shrimp.

Improving red-color performance, immune response and resistance to Vibrio parahaemolyticus on white shrimp Penaeus vannamei by an engineered astaxanthin yeast.

Astaxanthin (AST), a super antioxidant with coloring and medical properties, renders it a beneficial feed additive for shrimp. This study conducted a white shrimp feeding trial of 3S, 3'S isoform AST, which was derived from metabolic-engineered Kluyveromyces marxianus fermented broth (TB) and its extract (TE) compared to sources from two chemically synthetic ASTs (Carophyll Pink [CP] and Lucantin Pink [LP]), which contain 3S, 3'S, 3R, 3'S (3S, 3'R) and 3R, 3'R isoforms ratio of 1:2:1. The effects on red coloration, immune parameters and resistance to Vibrio infection were evaluated. Four AST sources were incorporated into the diets at concentrations of 0 (control), 100 mg kg-1 (TB100, TE100, CP100, and LP100), and 200 mg kg-1 (TB200, TE200, CP200, and LP200). Results revealed that in week 4, shrimps that received AST-supplemented feeds, especially TB100, TB200, and TE200, significantly increased redness (a*) values. Immune responses including phagocytosis activity, superoxide-anion production, phenoloxidase activity, and immune-related genes were examined on days 0, 1, 2, 4, 7, 14, 21, and 28. Generally, shrimps that received AST-supplemented feeds exhibited higher immune responses on days 7 and 14 than the control feed. Gene expression levels of superoxide dismutase and glutathione peroxidase were significantly upregulated on days 7 and 14 in shrimps that received AST-supplemented feeds, while genes of penaeidins, antilipopolysaccharide factor, and lysozyme were upregulated on days 4, 7, and 14, especially received TB200 and TE200. Furthermore, shrimps that received TB100, TE100, CP100, and LP100 7 days were then challenged with Vibrio parahaemolyticus and the result demonstrated higher survival rates especially TB100 at 168 h than the control feed. In conclusion, incorporating AST into the diets enhanced shrimp red coloration, immune parameters, and resistance against V. parahaemolyticus infection. The K. marxianus-derived AST exhibited higher performance than did chemical AST to be a potential feed additive in shrimp aquaculture.

Dietary of Lactobacillus paracasei and Bifidobacterium longum improve nonspecific immune responses, growth performance, and resistance against Vibrio parahaemolyticus in Penaeus vannamei.

This study investigated the effects of two probiotics, namely Lactobacillus paracasei and Bifidobacterium longum, as feed additives on growth performance, nonspecific immunity, immune-related gene expression, and disease resistance against Vibrio parahaemolyticus in Penaeus vannamei. The experimental diets were prepared using L. paracasei and B. longum at concentrations of 105 and 107 CFU/g; these diets were referred to as P5, P7, B5, and B7. After 8 weeks of the diets, regarding growth performance, the B7 group showed the highest weight gain rate (890.34 ± 103.65%), special growth rate (4.08 ± 0.19%), and feed conversion rate (1.52 ± 0.19%) compared with the other groups. Moreover, the total hemocyte counts were significantly increased (p < 0.05) in the P7 groups on day 14 during the 28-day feeding trial. The phagocytosis rate in all experimental groups was increased on day 14 and was persistently significantly activated to day 21, especially in the P7 and B5 group. The phagocytic index of the P7 group showed a significant increase on day 14 and persistent activation to day 21. In the analysis of respiratory burst activity and phenoloxidase activity, the P7 and B5 groups showed a significant increase on day 7 and persistent activation to day 21. The expression level of the immune-related genes of superoxide dismutase, clotting protein, Penaeidin2, Penaeidin3, Penaeidin4, anti-LPS factor, crustin, and lysozyme was significantly increased in the experimental groups, especially in the P7 group. Furthermore, the optimum conditions of feed additives were determined in challenge trials conducted using P7 and B5. Shrimps fed P7 and B5 showed an increased survival rate (72.73% and 66.67%) after the V. parahaemolyticus challenge. In sum, the results revealed that B. longum, as a feed additive at 107 CFU/g, enhanced growth performance. L. paracasei at 107 CFU/g and B. longum at 105 CFU/g can enhance nonspecific immune responses and immune-related gene expression, and 107 CFU/g L. paracasei has the highest resistance ability for V. parahaemolyticus. Thus, dietary supplementation with L. paracasei and B. longum may be a valuable approach in white shrimp aquaculture.

Effect of dietary supplementation with Moringa oleifera leaf extract and Lactobacillus acidophilus on growth performance, intestinal microbiota, immune response, and disease resistance in whiteleg shrimp (Penaeus vannamei).

This study investigated the effect of the moringa (Moringa oleifera) leaf extract and Lactobacillus acidophilus individually or combined on growth performance, enzyme activity, intestinal and hepatopancreatic histology, intestinal microbiota, immune response, and resistance against Vibrio alginolyticus and Vibrio parahaemolyticus in whiteleg shrimp (Penaeus vannamei). Six diets were formulated: three diets without L. acidophilus containining 0 (control, ME0), 2.5 (ME2.5), and 5.0 g/kg of moringa (ME5.0) and the same three diets containing L. acidophilus at 1 × 107 CFU/g of diet (ME0+P, ME2.5 + P, and ME5.0 + P, respectively). Growth performance was measured after 60 days of the rearing period. On the final day, the shrimp were sampled to assess enzyme activity, intestinal and hepatopancreatic histology, and gut microbiota. Shrimp hemocytes were examined on Days 0, 1, 2, 4, 7, 14, 21, and 28 to measure the immune response in terms of the total hemocyte count, phenoloxidase activity, phagocytosis, and superoxide anion production. Furthermore, the shrimp were challenged with V. alginolyticus and V. parahaemolyticus. The results revealed that ME2.5 + P significantly increased (P < 0.05) final weight, weight gain, specific growth rate, enzyme activities, and villi height compared with ME2.5 and control. Wall thickness was increased in the shrimp fed diet supplemented with moringa and L. acidophilus compared with the control shrimp. Hepatopancreatic histology revealed that R cells were more abundant in the shrimp fed diet containing moringa and L. acidophilus compared with those fed diet containing moringa alone (P < 0.05) at the same concentration. High-throughput sequencing analysis indicated that the dietary supplementation with moringa and L. acidophilus affected the gut microbiota composition. All gene functions, members of KEGG level 2, related to metabolism were increased in diet supplemented with moringa with or without L. acidophilus compared with the control group. The immune assay revealed that the total hemocyte count, phenoloxidase activity, phagocytic rate, superoxide anion production, and immune-related gene expression (including those of prophenoloxidase II, alpha-2-macroglobulin, penaeidin2, antilipopolysaccharide factor, crustin, lysozyme, glutathione peroxidase, and superoxide dismutase) were higher in the experimental groups than in the control group on several observed days; however, the increases were observed more often in the ME2.5 + P group than in the other treatment groups. Furthermore, the ME2.5 + P group exhibited a significantly higher survival rate (P < 0.05) in the challenge test against V. alginolyticus and V. parahaemolyticus. In conclusion, supplementation with dietary moringa and L. acidophilus at ME2.5 + P improved growth performance, immune system, and resistance against Vibrio in the shrimp.