Effect of Replacing Fish Meal with Fermented Mushroom Bran Hydrolysate on the Growth, Digestive Enzyme Activity, and Antioxidant Capacity of Allogynogenetic Crucian Carp (Carassius auratus gibelio)

The objective of this study was to investigate the effects of partially replacing fish meal with FMBH on the growth, digestive enzyme activity, and antioxidant capacity of allogynogenetic crucian carp. Fermented mushroom bran hydrolysate (FMBH) was prepared by enzymatic hydrolysis after the solid fermentation of mushroom bran (MB) inoculated with Ganodermalucidum and Saccharomyces cerevisiae. Nine hundred fish were allotted to six groups and were fed diets in which the fish meal was replaced with 0% (FMBH-0), 16% (FMBH-16), 32% (FMBH-32), 48% (FMBH-48), 64% (FMBH-64), and 80% (FMBH-80) FMBH. After 71 days, the weight gain ratio and the protein efficiency ratio of FMBH-64 and FMBH-80 were significantly higher than those of the FMBH-0 group (P < 0.05). No significant differences were noted for the specific growth ratio, feed conversion ratio, or survival rate among all groups (P > 0.05). The protease activity in the midgut was not significantly different among all groups (P > 0.05). However, compared with FMBH-0, the protease activity in the fore gut of FMBH-32, FMBH-48, FMBH-64, and FMBH-80 was significantly elevated (P < 0.05), the amylase activity in the fore gut and midgut of FMBH-32, FMBH-48, FMBH-64, and FMBH-80 was significantly elevated (P < 0.05), and the lipase activity in the fore gut and midgut of FMBH-48, FMBH-64, and FMBH-80 was significantly elevated (P < 0.05). Compared with FMBH-0, FMBH-80 demonstrated a significant increase in the serum total antioxidant capacity and anti-superoxide anion activity (P < 0.05), but a significant decrease in the maleic dialdehyde content (P < 0.05). FMBH-48 and FMBH-64 also significantly increased the anti-superoxide anion activity (P < 0.05). Therefore, replacing a 64%-80% proportion of dietary fish meal with FMBH could improve the growth, digestive enzyme activity, and antioxidant capacity of allogynogenetic crucian carp.