Compound Chinese herbal extract (RMCP) supplementation improves defense against Aeromonas veronii infection in Chinese mitten crab Eriocheir sinensis

Chinese herbal medicinal preparations are considered promising immunoprophylactic agents in aquaculture. Yet the protection of Chinese mitten crabs Eriocheir sinensis against Aeromonas veronii infection using Chinese herbal medicinal preparations is still unknown. In this study, a 45-day feeding trial was carried out to examine the defense ability against A. veronii infection in E. sinensis fed diets supplemented with the compound Chinese herbal extract (RMCP), a combination of water extracts from Rhizoma coptidis, Moslae herba, Caesalpinia sappan, and Punica granatum. The results revealed that the RMCP supplementation significantly and dose-dependently augmented weight gain and specific growth rate of crabs as well as their serum and hepatopancreatic acid phosphatase, alkaline phosphatase, catalase, lysozyme, and superoxide dismutase activities, resulting in significant improvement in the growth performance, immunity, and antioxidant capability of crabs. Additionally, the RMCP supplementation notably improved the abundance and diversity of the intestinal bacterial community in crabs and conferred significant protection of crabs against A. veronii infection with 10-day survival rates ranging from 40.00 to 63.33%. To the best of our knowledge, this is the first study to clarify the protective effects of a compound Chinese herbal extract against A. veronii infection in Chinese mitten crabs.