Dietary chitosan alleviates intestinal and liver injury of hybrid sturgeon (Acipenser baerii♀ × A. schrenckii♂) induced by Aeromonas hydrophila infection

Chitosan has been universally used as a feed additive, whereas its regulation on hybrid sturgeon (Acipenser baerii♀ × Acipenser schrenckii♂) after bacterial infection has not been well studied. This study was conducted to investigate the therapeutic intervention with dietary chitosan on alleviating intestinal and liver injury of hybrid sturgeon induced by Aeromonas hydrophila infection. Healthy sturgeons were pre-challenged by treating with A. hydrophila supplemented diets for 1 week and then fed with diets containing different levels (0.00, 1.00, 3.00 and 5.00 g/kg) of chitosan for 8 weeks. The results showed that there were significant differences (P < 0.05) of FBW, WG, SGR, FI and FCR in sturgeon fed chitosan diets compared to those in fish fed the control diet. Significant enhancement (P < 0.05) of LZM, ACP, AKP and MPO activities were observed in all fish serum therapeutically administrated with chitosan. Compared to control diet, the CAT, SOD and GSH-Px capacity were significantly increased (P < 0.05), and the MDA content was decreased in liver of sturgeons fed chitosan supplemented diets. Moreover, not only mitigate tissue lesions in the liver and intestine, but also visible increase (P < 0.05) of goblet cells in fish mid intestine as well as evident increase (P < 0.05) of the muscular thickness and villus height (except in group CHI1) in fish spiral valve were observed after therapeutic chitosan supplementation. The fish therapeutically administrated with 1.00, 3.00 and 5.00 g/kg chitosan conferred 50.00%, 75.00%, 62.50% relative percent survival, respectively, for hybrid sturgeons pre-challenged with A. hydrophila. These results suggested that therapeutic administration of chitosan by sturgeon not only increases their growth performance, antioxidant activity and non-specific immunity but also alleviates intestinal and liver injury in fish challenged by A. hydrophila.