Effects of Dietary Proanthocyanidins Supplementation on Growth Performance, Digestive Enzymes Activities and Microbiota in the Intestine of Juvenile American Eels (Anguilla rostrata) Cultured in Cement Tanks

Abstract

This trial was conducted to investigate the effects of proanthocyanidins (PACs) on the growth performance, digestive enzymes activities and microbiota in the intestines of juvenile American eels (Anguilla rostrata) cultured in cement tanks. Six cement tanks stocked with similar fish size and weight (about 120 g/fish and 2116 kg/tank) were randomly divided into a control group fed with a commercial diet and a PACs group fed with a commercial diet supplemented 400 mg/kg PACs, with three replicates in each group. The trial period lasted 60 days. The finial fish weight and weight gain rate were significantly improved by PACs supplementation (P<0.05). There were no significant differences in feed efficiency and feeding rate between the control group and PACs group (P>0.05). Activities of protease in intestines were significantly enhanced by PACs supplementation (P<0.05), however dietary PACs supplementation had no significant effect on the activities of amylase and lipase (P>0.05). Furthermore, dietary PACs supplementation increased the richness and decrease the diversity of intestinal microbiota. At the phylum level, the higher relative abundance of Proteobacteria and the lower relative abundances of Firmicutes and Actinobacteria were found in PACs group compared to control group. At the genus level, PACs supplemented in diet significantly increased the relative abundances of Candidatus Arthromitus, Paracoccus and Eubacterium hallii (P>0.05). In conclusion, dietary 400 mg/kg PACs supplementation improved growth performance and activity of protease in intestine, and modulate intestinal microbiota of juvenile American eel cultured in cement tanks.

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

“…In the present study, juvenile American eels of CAs group had a lower abundance of Firmicutes compared with the control group. Firmicutes was the main phyla in many fish species, but some of these bacteria could cause the lower growth rate of European eel (Shi et al, 2020;Wang et al, 2020). These results indicated that CAs might increase the abundance of beneficial microbiota at the phylum level related to nutrient digestion and absorption.…”

“…The microbiota plays an important role in the development of normal intestinal function, stimulation of the innate immune response, and maintenance of the balance of the intestinal environment (Wang et al, 2020). Alpha diversity could reflect the richness and diversity of microbial communities, mainly including indexes of Chao1, Shannon and Simpson (Xu et al, 2019).…”

“…In this study, the proportions of Proteobacteria, Actinobacteria and Bacteroidetes in the intestine of juvenile American eels from CAs group were higher than those of the control group. Proteobacteria members have been reported to decompose chemical compounds that can serve as a source of energy and metabolites, and several researchers have verified that some bacteria of Proteobacteria in the gut of healthy fish might significantly contribute to the digestive function, and identified as protease-producing bacteria dominant in carnivorous fish (Shi et al, 2020;Wang et al, 2020). Some members of the Actinobacteria have been shown to positively stimulate the immune system and have recently been used as probiotics to protect against Vibrio anguillarum infection ( Navarrete et al, 2013).…”

“…Since eel was introduced to China in the early 1990s with continuous development, it has become one of the most important economic species for freshwater aquaculture in China and has made an important contribution to the development of the Chinese fisheries economy (Zhai et al, 2020;Yuan et al, 2021). With the natural stocks of European eel (Anguilla anguilla) and Japanese eel (Anguilla japonica) declining sharply, American eel (Anguilla rostrata) has become one of the main eel farming species in southeastern China and is mostly cultured in cement tanks (Wang et al, 2020;Zhai et al, 2020). Therefore, this experiment was conducted to investigate the effects of dietary CAs supplementation on growth performance, activity of intestinal digestive enzymes, morphology and microbiota in the intestine of juvenile American eels cultured in cement tanks.…”

Effects of Dietary Supplementation of Peanut Skin Proanthocyanidins on Growth Performance and Lipid Metabolism of the Juvenile American Eel (Anguilla rostrata)

“…Eels, reputed as “ginseng in water”, are one of the most common fish species cultured around the world, and they play an important role in international trade [ 14 ]. The American eel has become the main cultured eel species in Asia since European eels ( Anguilla anguilla ) have been listed as extremely endangered species [ 14 , 15 ]. The purpose of the present study was to investigate the effects of dietary supplementation of PSPc on the growth performance and lipid metabolism of juvenile American eels.…”