Effects of dietary hydrolyzable tannins on growth performance, antioxidant capacity, intestinal microflora and resistance against Vibrio parahaemolyticus of juvenile Pacific white shrimp, Litopenaeus vannamei (Boone, 1931)

Abstract

Tannins have great potential as an alternative to in-feed antibiotics. However, no study has investigated the effects of tannins on shrimp. The present study assessed the eff ;ects of hydrolyzable tannins (HTs) fed at different inclusion levels (F0: control, F0.5: 0.05 %, F1: 0.1 %, F1.5: 0.15 % and F2: 0.2 % (g−1 feed) on the growth performance, antioxidant capacity, immune response, intestinal microflora and resistance to Vibrio parahaemolyticus of juvenile Pacific white shrimp (Litopenaeus vannamei). After 60 days of the feeding trial, a significant increase (P < 0.05) of weight gain rate (WGR), specific growth rate (SGR), activities of alkaline phosphatase (ALP), acid phosphatase (ACP), superoxide dismutase (SOD) and trypsin in serum and hepatopancreas, and the expression level of catalase (CAT), Cu/Zn superoxide dismutase (Cu/Zn-SOD) and glutathione peroxidase (GPx) gene in the hepatopancreas of 0.15 % HT treated groups were achieved. The dietary supplementation of HTs also changed the composition of intestinal microflora. At the phylum level, Proteobacteria accounted for the majority of bacteria, followed by Firmicutes, Bacteroidetes and Actinobacteria. At the genus level, Stenotrophomonas, Ruegeria, and Photobacterium were dominant in the F0.5, F1, and F1.5 groups, respectively. The relative abundance of Vibrio and Carboxylicivirga decreased in the intestines of shrimp fed with HTs diets. Furthermore, F1.5 group showed the highest relative percent survival value (80 %) (P < 0.05), which indicates that the supplementation of 0.15 % HTs in challenge test significantly enhanced the resistance of shrimp against V. parahaemolyticus infection after 24 h. These results indicated that 0.15 % HTs could remarkably improve the growth performance, antioxidant capacity, intestinal microflora, and resistance against V. parahaemolyticus of L. vannamei, and can be a potential feed additive for shrimp in aquaculture. According to our study, the optimal dietary supplementation dosage of HTs is 0.15 % feed in diets.