The screening of traditional Chinese herbs on nonspecific immune response and protection of Pacific white shrimp (Litopenaeus vannamei) from Vibrio harveyi infection

Abstract

Twenty-three species of dry Traditional Chinese herbs (TCHs) were examined for the experiment. Bacteriostasis experiments in vitro were carried out for screening 23 TCHs on inhibiting Vibrio harveyi and four screened species (Galla chinensis, Terminalia chebula, Scutellaria baicalensis, Rheum officinale) which have antibacterial activity were decoct, concentrated, and mixed with diets at 2%, respectively. After feeding for 28 days, shrimps were challenged by V. harveyi, and then mortality was recorded. With regard to hemocyte phagocytic activity, activities of lysozyme (LZM) were measured on day 0, 7, 14, 21, and 28. Relative percentage survival (RPS) was also investigated in each TCH group. Phagocytic activity (PA) phagocytic index (PI), LZM, and RPS (with the exception of T. chebula and R. officinale) of Pacific white shrimp can be significantly increased when fed 2% TCH extracts. RPS of S. baicalensis was the highest, reaching 51.86% on day 28, then the G. chinensis group, whereas R. officinale group was the lowest, when the Pacific white shrimp challenged with V. harveyi. It can be concluded that S. baicalensis and G. chinensis could be used to enhance shrimp’s immunity and disease resistance in cultured Pacific white shrimp.