Effects of dietary supplementation with β-glucan and Bacillus subtilis on growth, fillet quality, immune capacity, and antioxidant status of Pengze crucian carp (Carassius auratus var. Pengze)

A 70-day feeding trial was conducted to investigate the effects of dietary supplementation with prebiotics β-glucan (BG group) and probiotics Bacillus subtilis (BS group) on growth performance, fillet quality, immune response, and antioxidant status of Pengze crucian carp (Carassius auratus var. Pengze). The results showed that supplementation of B. subtilis significantly improved the growth performance than other groups whereas feed efficiency was unaffected by dietary treatments. The textures of muscle in terms of hardness, springiness, cohesiveness, gumminess, chewiness, and resilience were higher in BG and BS groups than Control group. Supplementation of β-glucan and B. subtilis acted as an hypolipidemic in terms of decreasing the total cholesterol, high-density lipoprotein, and low-density lipoprotein whereas, increased the immune responses in serum measured by acid phosphatase, alkaline phosphatase, and catalase activities. Dietary supplementation of β-glucan and B. subtilis significantly improved the fold height and microvillus height in contrast to basal diet. Moreover, β-glucan could significantly increase digestive capacity observed in terms of an increase in amylase and trypsase activities, and B. subtilis significantly increased amylase and lipase activities in intestine. β-glucan and B. subtilis supplementation enhanced the immunity and antioxidant capacity via an increase in acid phosphatase, alkaline phosphatase, glutathione peroxidase, reduce glutathione, catalase, and total superoxide dismutase activities, accompanied by a significant reduction in malondialdehyde. Overall, the results indicated that B. subtilis improved the growth performance by increasing the digestive enzymes activities and improving the intestinal morphology. β-glucan and B. subtilis supplementation significantly improved the fillet quality, immune responses and antioxidant status of Pengze crucian carp.