| Sea cucumber (Stichopus japonicus Selenka), with high edible and medicinal value, contains abundant of various nutrients. In China, Russia, Japan and South Korea, sea cucumber is important economic breeding species, which enjoys a huge market demand. So the yield and quality requirements of the sea cucumber culture is higher and higher. Chinese sea cucumber culture scope mainly concentrated in the north, always with big breeding density. It is very important to study the efficient and healthy of sea cucumber feed additives. This paper used chitosan and chitosan oligosaccharide and its complexes as sea cucumber feed additives, to study the influence on sea cucumber growth, non-specific immune related enzyme activity and quality related indexes, and to provide a scientific basis for the application of chitosan and chitosan oligosaccharide and its complexes in sea cucumber culture. The main experimental contents and results are as follows:1. An 8-weeks trail was conducted to evaluate how did low molecular weight chitosan (LMWC,35 kDa) and high molecular weight chitosan (HMWC,400 kDa) exert an influence on growth and the activity of nonspecific immune related enzymes and quality related indexes of sea cucumber(Stichopus japonicas Selenka). The juvenile sea cucumber, whose initial average weight was 6.77±0.01 g, was used as the experimental subject. Moreover, the basic diet was used as control, and two experimental diets were formulated by adding 1% different molecular weight chitosan to the basal diet. Results showed that both LMWC and HMWC could promote the growth of sea cucumber, and the specific growth rate (SGR) of LMWC group had a remarkably difference compared with control group (P<0.05). Compared to the control, the activity of total superoxide dismutase (T-SOD) of coelomocytes was strikingly increased in experimental groups (P<0.05). LMWC could enhance acid phosphatase (ACP) activity significantly (P<0.05), as well as alkaline phosphatase (AKP) and nitric oxide synthase (NOS) activities. The activities of AKP and NOS in HMWC group were conspicuously higher than control group (P<0.05). The resaults of quality related indexes showed that LMWC could remarkably enhance the content of collagen protein, total polysaccharide and unsaturated fatty acids in body wall of sea cucumber (P<0.05). HMWC could also increase the content of collagen and total polysaccharide. Both LMWC and HMWC didn’t influence the content of total glycosides. All the results demonstrated that chitosan supplemented in diets could stimulate sea cucumber’s growth and activities of immune related enzymes and have a beneficial effects on quality of sea cucumber.2. An 8-weeks trail was conducted to evaluate the effect of chitosan oligosaccharide (≤3000 Da) on growth and the activity of nonspecific immune related to enzymes and quality related indexes of sea cucumber(Stichopus japonicas Selenka). The experimental subjuct was juvenile sea cucumber, whose initial average weight was 6.77±0.01 g. The basic diet was used as control, and experimental diet was formulated by adding 1% chitosan oligosaccharide to the basal diet. Results showed that COS could promote the SGR of sea cucumber remarkably (P<0.05), and promoted the activity of T-SOD, ACP and AKP significantly (P<0.05), showing obvious immunological enhancement effect. At the same time, researches on the quality related indexes of body wall showed that the total polysaccharide content in experimental group was significantly higher than the control group (P<0.05), collagen content increased. All the results demonstrated that COS can promote the growth of sea cucumber, improve immunity, and have a certain role in promoting the quality index.3. An 8-weeks trail was conducted to evaluate how did chitosan oligosaccharide complex with rare earth elements (COS-REE) exert an influence on growth and the activity of nonspecific immune related enzymes and quality related indexes of sea cucumber (Stichopus japonicas Selenka). The juvenile sea cucumber, whose initial average weight was 6.77±0.01 g, was used as the experimental subject. Moreover, the basic diet was used as control, and four experimental diets were formulated by adding 300 mg/kg COS-La (COS-Lal),600 mg/kg COS-La (COS-La2),300 mg/kg COS-Ce (COS-Ce 1),600 mg/kg COS-Ce (COS-Ce 2) to the basal diet. The experimental results show that, all the experimental group significantly increased the SGR (P<0.05). 600 mg/kg COS-REE can significantly improve the activity of SOD, AKP and ACP (P<0.05).300 mg/kg adding amount also had an enhancing effect on immune enzyme activity. But all the experimental groups did not influence the activity of NOS. Quality reletated indexes of sea cucumber showed that COS-Lal, COS-Cel and COS-Ce2 could significantly increase the collagen content (P<0.05). COS-Lal, COS-La2 and COS-Ce2 could significantly increase the total polysaccharidecontent (P<0.05). All the experimental groups did not affect the content of total glycosides in sea cucumber. Compared with the control group, the PUFA content was lower than that of control group. Experiments confirmed that the addition of certain amount of COS-REE can promote the growth of sea cucumber, improvement of nonspecific immunity, and can correspondingly improve the quality of Stichopus japonicas. |
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