Effects of partial replacement of fish meal by yeast hydrolysate on antioxidant capability, intestinal morphology, and inflammation-related gene expression of juvenile Jian carp (Cyprinus carpio var. Jian).

This study aimed to evaluate the effects of fish meal (FM) replacement by yeast hydrolysate (YH) on liver antioxidant capability, intestinal morphology, and inflammation-related genes of juvenile Jian carp (Cyprinus carpio var. Jian). A total of 600 fish (average initial weight 19.44 ± 0.06 g) were randomly selected and divided into five groups. Five isonitrogenous and isocaloric diets replacing FM by YH 0% (YH0), 1% (YH1), 3% (YH3), 5% (YH5), and 7% (YH7) were formulated. Each diet was tested in four replicates for 10 weeks. The results have shown that, compared to the control group (YH0), liver total superoxide dismutase (t-SOD), catalase (CAT), glutathione peroxidase (GPX), and glutathione (GSH) activities of fish fed YH1 and YH3 diets were significantly higher (P < 0.05). Liver malondialdehyde (MDA) concentration significantly increased as supplementation levels of YH increased from 1 to 7% (P < 0.05). Moreover, intestinal microvillus length of juvenile Jian carp fed YH diets were significantly higher than that of fish fed the control diet (P < 0.05). In proximal intestine, the relative expression levels of inflammation-related genes (ALP, IL-1β, and TNF-α) in YH7 were significantly higher than that in the control group (P < 0.05). However, in midintestine, the expression levels of these genes in YH3 were significantly lower compared to the control group (P < 0.05). The results of this study indicated that dietary replacement of FM by 3%YH could improve antioxidant capability and intestinal microvillus morphology, as well as enhance the non-specific immunity of juvenile Jian carp.