Effects of dietary compound acidifiers supplementation on growth performance and intestinal health of juvenile American eels (Anguilla rostrata) cultured in cement tanks

Abstract

This experiment was conducted to investigate the effects of compound acidifiers (CAs) on the growth performance and intestinal health of juvenile American eels (Anguilla rostrata) cultured in cement tanks. Six cement tanks with similar fish size and weight (approximately 4 g/fish and 87 kg/tank) were randomly divided into control group and CAs group with three replicates each. The fish of two groups were fed commercial diet and commercial diet supplemented with 4 g/kg CAs, respectively. The trial period was 56 days. The dietary CAs supplementation significantly increased final fish weight, weight gain rate, specific growth rate and feed intake (P<0.05). There were no significant differences in feeding rate, feed efficiency, and survival rate between the control group and CAs group (P>0.05). Protease activity in intestine was increased significantly by CAs supplementation (P<0.05). Lipase activity and amylase activity were similar between control group and CAs group (P>0.05). CAs supplementation significantly increased the villi length and thickness of the intestinal muscular layer (P<0.05). Dietary CAs supplementation increased the richness and the diversity of intestinal microbiota. At the phylum level, the higher relative abundances of Proteobacteria, Actinobacteria and Bacteroidetes and the lower relative abundance of Firmicutes were observed in CAs group compared to the control group. At the genus level, dietary CAs supplementation significantly increased the relative abundances of Faecalitalea, Sphingomonas, Sutterella and Mycobacterium (P<0.05). In conclusion, the dietary 4 g/kg CAs supplementation might improve the growth performance and intestinal health of juvenile American eels cultured in cement tanks.