Effects of enzymatic chicken pulp on liver antioxidant capacity, intestinal physical barrier and microflora of Micropterus salmoides

In order to evaluate the effects of enzymatic chicken mashes on healthy culture of Micropterus salmoides, fish meal in basal diet was replaced with 3.5% fish meal by stickwater from fish processing (SW) and enzymatic chicken pulp (EC) by the equal amounts, respectively, and three isolipid (EE 11.3%) diets were prepared. M. salmoides with an initial body weight of (9.25±0.13) g were fed in a circulation system for 8 weeks. The results indicated that there were no significant differences in weight gain rate (WGR), specific growth rate (SGR) and feeding rate (FR) of M. salmoides among all treatment groups. The activity of total superoxide dismutase (T-SOD), content of malondialdehyde (MDA) and expression levels of anti-inflammatory cytokines (TGF-β) and pro-inflammatory cytokines (IL-8) in liver in EC group were significantly better than those in control group (basal diet) and SW group. Compared with other treatments, after adding EC, the relative expressions of occludin, zo-1 and claudin-1 in intestinal tract were significantly up-regulated, while the activities of diamine oxidase (DAO), D-lactic acid (D-Lac) and lipopolysaccharide (LPS) contents in serum were significantly decreased. At the same time, it was also observed that EC affected the intestinal microflora abundance (OTUs and Chao1) of M. salmoides, increased the (Bacillus) at the genus level, and reduced the abundance of potentially probiotic bacteria of some potentially harmful bacteria (Escherichia-shigella, Acinetobacter, Vibrio and Mycoplasma). Further phenotypic prediction showed that the addition of EC significantly reduced the proportion of Gram-negative bacteria and increased the proportion of Gram-positive bacteria. All in all, the addition of EC in the diet does not affect the growth of M. salmoides, but enhances the antioxidant capacity of liver and intestinal physical barrier and improves intestinal microflora. EC can be used as high-quality protein source for M. salmoides.