Chitosan Enhanced the Growth Rate, Antioxidant Activity, Immunity, Intestinal Morphology and Disease Resistance against Aeromons hydrophila of Juvenile Hybrid Sturgeon (Acipenser baerii♀ × Acipenser schrenckii♂)

Abstract This study was performed to evaluate the effects of dietary chitosan on hybrid sturgeon (Acipenser baerii♀ × Acipenser schrenckii♂). Sturgeons (18.18 ± 0.08 g) were randomly divided into four groups: control (0.00 g/kg), CHI1 (1.00 g/kg), CHI3 (3.00 g/kg) and CHI5 (5.00 g/kg), and fed with corresponding diets for 8 weeks. Then 30 fish from each group were intraperitoneally infected with A. hydrophila, and the mortality was recorded for 14 days. The results showed that there were significant differences of FBW, WG, SGR, FI and FCR in sturgeon fed chitosan diets compared to those in fish fed the control diet. Significant enhancement of LZM, ACP, AKP and MPO activities were observed in all fish serum fed the chitosan supplemented groups. Compared to control diet, the CAT, SOD and GSH-Px capacity were significantly increased, and the MDA content was decreased in liver of sturgeons fed chitosan supplemented diets. Moreover, visible enhancement of muscular thickness and goblet cells of fish mid intestine as well as evident increase in the muscular thickness and villus height of fish spiral valve were observed in the chitosan supplemented groups. The challenge test with A. hydrophila resulted in mortalities of 100%, 76.67%, 53.33% and 50.00% for hybrid sturgeons fed control, CHI1, CHI3, and CHI5 diets respectively. Taken together, our study revealed that dietary chitosan enhanced growth performance, elevated antioxidant capability and immunity, regulated intestinal morphology, and promoted resistance against A. hydrophila in hybrid sturgeon. The optimal dose was 3.00 g chitosan/kg diet for hybrid sturgeon.