Effects of bupleurum and its extracts on intestinal enzyme activity, flora, structure and expression of non-specific immune-related genes of juvenile Cyprinus carpio infected by Aeromonas vickerii
Authors: Yan Xuecheng , Chen Chengxun 
Published: November 2023

Abstract
Purpose This paper studies the effects of bupleurum and its extract on intestinal function of juvenile Cyprinus carpio, lipid metabolism, foregut digestive enzymes, intestinal flora, intestinal structure and non-specific immune-related genes of juvenile Cyprinus carpio were analyzed before and after infection by artificial infection with aeromonas vickerii. [Methods]Three groups (K group, feeding basic feed;Piglets in group C were fed basic diet +5‰ bupleurum meal, and piglets in group T were fed basic diet +5‰ bupleurum extract). There were 3 replicates in each group and 40 fish in each replicate. Juvenile Cyprinus carpio with initial body weight of (21±0.5) g were fed for 14 days.
Main results
Before infection: the contents of TC and LDL in C and T groups were significantly decreased (P<0.05),HDL was significantly increased (P<0.05), and TBL content in C group was significantly decreased (P<0.05) at 14 days. At 14 days, the activities of LPS and PRO in group C were significantly increased (P<0.05). Compared with group K, sobs, shannon, ace and chao index increased in group C and T, and simpson index decreased. At the phylum level, the dominant bacterial groups in each group were Proteobacteria, Firmicutes, Fusobacteria and Actinobacteria. On the genus level, the relative abundance of cetobacterium in group C and T is significantly lower than that in group K. The villus length and muscle thickness in group C were significantly higher than those in group K (P<0.05).
After infection: LPS and AMS were decreased in K group (P<0.05), but there was no significant difference in other groups (P>0.05). Compared with group K, sobs, shannon, ace and chao index increased in group C and T, and simpson index decreased. At the phylum level, the relative abundance of Proteobacteria increased in groups C and T and decreased in groups firmicutes compared with group K.The relative abundance of groups C and K decreased. The relative abundance of actinomycetes increased in group C and decreased in group T and K. At the genus level, the relative abundance of cetobacterium in group C and group T decreased less than that in group K. The relative abundance of aeromonas and acinetobacter in groups C and T was less than that in group K. After group C was infected with Aeromonas vickerii, flavobacteria decreased significantly, and pilomonas increased significantly. The villus length and muscle thickness in group C were significantly higher than those in group K (P<0.05). At 96h, the relative expressions of Hsp70 and Hamp in group C were significantly higher than those in groups K and T (P<0.05). [Conclusions] Dietary supplementation of bupleurum and its extract can improve lipid metabolism, intestinal enzyme activity, intestinal flora diversity, intestinal structure, non-specific immune gene expression and resistance to aeromonas vickerii infection of juvenile cyprinus carpio.However, the action time and effect of the two groups are different, and the effect is more prominent than that of bupleurum group.