Abstract:The study was conducted to investigate the impact of Astragalus polysaccgarudes(APS) microcapsules (drug loading 17%) on the growth, nonspecific immune indices and resistance of Apostichopus japonicas against Vibrio splendidus infection.APS microcapsules were added at graded levels (1%, 3%, and 5%) to the basal diet to formulate three practical compound diets. Continuous 35-day feeding trials were carried out on A. japonicus at initial body weight of 22.0±1.0g. After feeding the diets for 35 days, specific growth rate (SGR) for the 5% treatment was 0.51%/d, which was significantly higher than the control. The activities of serum acid phosphatase (ACP), superoxide dismutase (SOD), and myeloperoxidase (MPO) increased significantly (P<0.05) in the 3% treatment. During the experiment these factors were determined at 7-day intervals. The activity of ACP was 11.2U/100ml at 28d during the experiment (P<0.05), the activity of SOD was 63.3U/ml at 21d (P<0.05), and the activity of MPO was 40MPO unit/ml at 21d (P>0.05). After the feeding trial, a V. splendidus injection challenge was given to the sea cucumbers to test the effects of APS microcapsule. The 3% treatment showed significantly better survival than the control (P<0.05). It is suggested that supplementation of 3% APS microcapsules has the greatest effects on growth, immunity and disease resistance in A. japonicas against V.splendidus. In addition, there was a direct relationship between the level and time of treatment, and the immunity.
