Abstract
A 4-week feeding trial was conducted to determine the effects of different dietary supplements on the growth, immunity and resistance of sea cucumber Apostichopus japonicus against Vibrio splendidus infection. The control group was supplied with blank microcapsules, and Astragalus polysaccharide (APS) microcapsules, tuckahoe polysaccharide (TPS) microcapsules, (APS + TPS) microcapsules, (APS + TPS) microcapsules + Bacillus subtilis, were tested for effects. Coelomic fluid was collected at 7-day intervals to test activities of lysozyme (LSZ), superoxide dismutase (SOD), alkaline phosphatase (AKP), and complement 3 (C3) content. After the feeding trial, the specific growth rate of sea cucumbers fed a diet supplemented with (APS + TPS) microcapsules + B. subtilis was significantly increased (P < 0.05); activities of LSZ, SOD, AKP and C3 content were significantly higher than in other groups (P < 0.05). The challenge test showed that the cumulative mortality of sea cucumbers fed a diet supplemented with (APS + TPS) microcapsules + B. subtilis reduced significantly (P < 0.05). In conclusion, dietary combinations of (APS + TPS) microcapsules + B. subtilis has a potential for use in diet formulations for sea cucumbers to significantly increase growth, immunity and disease resistance against V. splendidus infection.
Highlights
As a traditional food and invigorant, sea cucumber is nowadays extensively cultivated in China, which brings severe diseases
Wang et al [14] showed that supplements of 3 % conventional fine powder (CP) or superfine powder (SP) of Astragalus membranaceus root or 0.3 % Astragalus polysaccharide (APS), given over a period of 60 days could enhance the immune responses of A. japonicus
Some studies showed that feeding Chinese herb polysaccharides or their combinations could improve the growth of animals [18, 23]
Summary
As a traditional food and invigorant, sea cucumber is nowadays extensively cultivated in China, which brings severe diseases. That’s why antibiotics and chemotherapeutics are used today Abuse of these results in the spread of drug-resistant pathogens, environmental pollution and unexpected residues in aquaculture [1,2,3,4]. The most promising method for controlling sea cucumber disease in aquaculture is to strengthen its defense mechanisms by prophylactic administration of immunostimulants [5]. Many feeding trials and other tests have shown that polysaccharides have significant immunostimulatory effects through different mechanisms, for example by activating mouse B cells and macrophages, regulating the intestinal microbiota to improve productive performance, as well as enhancing the nonspecific immunity of some animals, such as lysozyme, superoxide, and alkaline phosphatase activities in fish or A. japonicus [10,11,12,13]. Application of microcapsule technology in polysaccharides has not been investigated, and has not been applied in A. japonicus, either
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