Effect of dietary chitosan oligosaccharide complex with Ce (IV) on growth, immunity and disease resistance against Vibrio splendidus of sea cucumber, Apostichopus japonicas

摘要

An 8-week feeding trial was conducted to investigate the effects of dietary chitosan oligosaccharide complex with cerium (Ce IV) (COS-Ce) on growth performance, nonspecific immunity and disease resistance of sea cucumber, Apostichopus japonicas. Five isonitrogenous (18.6) and isolipidic (1.1) practical diets were formulated with graded level of COS-Ce (0, 150, 300, 600 and 1200mgkg(-1) dry feed), which were named as COS-Ce/0, COS-Ce/150, COS-Ce/300, COS-Ce/600, COS-Ce/1200 respectively. Each diet was allocated to four replicates of sea cucumbers (Initial weight: 6.72 +/- 0.02g). Sea cucumbers were fed to apparent satiation once daily (19:00hours) for 56days. During the experiment, water temperature was kept at 16 +/- 0.5 degrees C, pH 7.8-8.2, dissolved oxygen beyond 5mgL(-1), ammonia nitrogen below 0.5mgL(-1) and salinity from 30 parts per thousand to 31 parts per thousand. Results showed that the specific growth rate of sea cucumbers was significantly higher in COS-Ce/600 than that in other four treatments. Activities of phagocytosis, respiratory burst, acid phosphatase and alkaline phosphatase in COS-Ce/600 were significantly higher than that in COS-Ce/0 (P<0.05) respectively. On the contrary, cumulative mortality was the lowest in COS-Ce/600 following 14days exposure to Vibrio splendidus (P<0.05). In conclusion, these results confirmed that dietary COS-Ce had beneficial effects on growth performance, nonspecific immunity and disease resistance of sea cucumber.