Effects of traditional Chinese medicine on nonspecific immunity and disease resistance of large yellow croaker, Pseudosciaena crocea (Richardson)

Abstract

The influence of traditional Chinese medicine (TCM) formulated from Astragalus Root ( Radix astragalin seu Hedysari) and Chinese Angelica Root ( Radix angelicae sinensis) at the rate of 5:1 (w/w) on nonspecific immunity including the number of phagocytes, lysozyme and complement activities, and disease resistance to Vibrio alginolyticus in large yellow croaker, Pseudosciaena crocea (Richardson) was determined. Minced fish (surimi) supplemented with 0.5% TCM had no influence on the nonspecific immunity of the fish ( P>0.05). On the other hand, the surimi with 1.0% and 1.5% TCM resulted in a significant increase in nitroblue tetrazolium (NBT) positive cells and lysozyme activities ( P<0.05) of experimented fish on 20, 25 and 30 days after feeding and led to evident enhancement of complement activities ( P<0.05) after 15 days of feeding. The highest survival rates (93.3%) in fish infected with V. alginolyticus were achieved with surimi containing 1.0% and 1.5% TCM, but the cumulative mortalities were 37% and 75% in fish fed with surimi containing 0.5% TCM and TCM-free surimi, respectively. These results indicated that the TCM formula might elevate the function of nonspecific immunity and enhance disease resistance of large yellow croaker.