Effects Of Compound Probiotics On Growth Performance,Immune Index And Intestinal Flora Structure Of Tongue Sole,Cynoglossus Semilaevis

The effects of dietary supplementation of compound probiotics on growth performance,serum immune index and intestinal flora structure in tongue sole(Cynoglossus semilaevis)were studied.A total of 216 C.semilaevis were randomly divided into 3 groups with 3 replicates per group and 24 fish per replicate.The fish of control group were fed a basal diet(BG),and those in experimental groups were fed the basal diet supplemented compound probiotics at a rate of 0.5%(LG)and 2%(HG),respectively.The experiment lasted for 21 days.The results showed as follows: compared with BG group,final mean body weight(FBW)and weight gain rate(WGR)of experimental groups was significantly increased(P<0.05);FBW and WGR of HG group were significantly higher than that of LG group(P<0.05);Feed conversion ratio(FCR)of LG and HG groups was significantly lower than that of BG group(P<0.05).Compared with BG group,serum activities of lysozyme(LZM),and alkaline phosphatase(ALP)were significantly increased in LG and HG groups(P<0.05);serum complement C3 and acid phosphatase(ACP)content of HG group were significantly higher than that of BG and LG groups(P<0.05).Compared with BG and LG groups,The group at HG had significantly higher number of OTUs and Alpha diversity indexes(P<0.05).The results of NMDS analysis showed that all samples of group BG and LG were clustered in the same dimension,while all samples of group HG were clustered separately in another dimension.According to PICRUSt analysis,the number of specific ko in samples of HG group on the 21 st day(HTG)was 241,which was significantly higher than that in samples of BG group and LG group on the 21 st day(P < 0.05).After further observation,many enzymes in the beta-LACTAM RESISTANCE pathway were annotated.Compared with BG group,there were a large number of genes involved in tetracycline biosynthesis reaction in samples of HG group.The results indicate that compared with the control group and the feed supplemented with 0.5% compound probiotics,2% compound probiotics could significantly improve the growth performance and immune index activity of tongue sole,and increase the species richness and diversity of intestinal flora.