Effects of dietary supplementation of inulin on survival, growth and intestinal microbiota of juvenile golden pompano (Trachinotus ovatus)

Prebiotics, such as inulin, can promote the growth of beneficial bacteria in the intestinal tract of animals, improve immunity, survival rate and growth performance, and have broad application prospects in the field of animal nutrition and feed. We conducted an 8-week feeding experiment to investigate the effects of dietary inulin on survival, growth performance and intestinal microbiota of juvenile golden pompano (Trachinotus ovatus) Initial average body mass of (18.85±0.02) g. Six isonitrogenous and isolipidic basal diets were supplemented with 0 (Control), 0.3%, 0.6%, 0.9%, 1.2% and 1.5% inulin. Results show that 1.5% inulin group had the highest survival rate, significantly higher than the other groups (P<0.05), and no significant difference was found among the other groups (P>0.05). The specific growth rate was the highest in 1.5% inulin group. The hepatosomatic index and intraperitoneal fat were significantly lower in inulin-included groups. The hepatosomatic index first decreased then increased with increasing levels of dietary inulin, with the lowest value in 0.9% inulin group. 1.2% and 1.5% inulin groups had significantly lower hepatosomatic index than the other groups. The fish fed with inulin-included diets had higher gut villus height than that in the control group. Proteobacteria, Firmicutes and Bacteroidetes were the predominant species of intestinal microbiota communities, but their abundance varied. The highest and lowest abundances of Proteobacteria were observed in 1.5% and 0.6% inulin groups, respectively. 0.6% inulin group had the highest abundances of Bacteroidetes and Firmicutes. The lowest abundances of Firmicutes and Bacteroidetes were found in 1.5% inulin group and control group, respectively. The predominant species at genus level were Achromobacter, Brevundimonas and Pandoraea. Achromobacter was most abundant in 1.5% inulin group. 0.6% inulin group had the lowest abundances of Achromobacter, Brevundimonas, Pandoraea, Delftia and Sphingomonas. Inulin supplementation increased the abundances of bacteria that are beneficial to the host such as Achromobacter and Prevotella. The results indicate that dietary supplementation of inulin at 1.5% can improve the survival and growth performance of T. ovatus.