Dietary chitosan moderates the growth rate, antioxidant activity, immunity, intestinal morphology and resistance against Aeromonas hydrophila of juvenile hybrid sturgeon (Acipenser baerii♀ × Acipenser schrenckii♂)

Abstract

This study investigated the effects of dietary chitosan on growth, antioxidant, immunity, intestinal morphology and resistance against Aeromonas hydrophila of hybrid sturgeon (Acipenser baerii♀ × Acipenser schrenckii♂). Sturgeons (18.18 ± 0.08 g) were randomly divided into four groups, fed with chitosan-supplemented diets for 8 weeks and then infected with A. hydrophila. The results showed significant differences of body weight gain, specific growth rate and feed conversion ratio in sturgeon fed chitosan and control diets. The oral administration of chitosan significantly increased the acid phosphatase, alkaline phosphatase, lysozyme, myeloperoxidase, superoxide dismutase, glutathione peroxidase and catalase activities, as well as the complement 3 and 4 contents and disease resistance against A. hydrophila. Moreover, enhancement of muscular thickness and goblet cells in mid intestine and increase of muscular thickness and villus height in spiral valve were observed in the chitosan supplemented groups. In addition, dietary chitosan-supplemented diets mitigated the changes of antioxidant and immune activity induced by A. hydrophila challenge, as well as prevented fish from bacterial invasion. The optimal dose was 3.00 g chitosan/kg diet for hybrid sturgeon.