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Two feeding trials were conducted in indoor circulating system to investigate the effects of complex immunostimulants in diets on growth, survival rate and nonspecific immunity of American white shrimp Litopenaeus vannamei.The results are summarized as follows:1. The growth response, respiratory burst (release of superoxide anion), phenoloxidase (PO), superoxide dismutase (SOD) and nitric oxide synthase (NOS) were measured in shrimps which had been fed diets supplemented with 0.1%G(β-glucan),0.2% G,0.03% N (Yeast Nucleotides),0.06% N,0.1% G+0.03% N,0.1% G+0.06% N,0.2% G+0.03% N,0.2% G+0.06% N in diets for 8 weeks. All treatments had no significant influence on survival rate of the shrimps (P>0.05). Significantly higher SGR was observed in all the treatments than that in control (P<0.05). Among the complex treatments:Shrimps fed the diet with 0.1% G+0.03% N had significant higher SOD activity and NOS activity; 0.1% G+0.06% N had significant higher respiratory burst activity, SOD activity and NOS activity; 0.2% G+0.03% N had significant higher respiratory burst activity, SOD activity and NOS activity; 0.2% G+0.06% N had significant higher respiratory burst activity, SOD activity and NOS activity.2. The growth response, respiratory burst (release of superoxide anion), phenoloxidase (PO), superoxide dismutase (SOD) and nitric oxide synthase (NOS) were measured in shrimps which had been fed diets supplemented with 0.1% VC(Vitamin C),0.2% VC,0.2% M (Mannose oligosaccharides, MOS),0.4% M, 0.1% VC+0.2% M,0.1% VC+0.4% M,0.2% VC+0.2% M,0.2% VC+0.4% M. All treatments had no significant influence on survival rate of the shrimps (P>0.05)。Significantly higher SGR was observed in all the treatments than that in control except the treatments with 0.1% VC,0.2% VC (P<0.05). Among the complex .treatments:Shrimps fed the diet with 0.1% VC+0.2% M had significant higher PO activity, SOD activity and NOS activity; 0.1% VC+0.4% M had significant higher respiratory burst activity, PO activity and NOS activity; 0.2% VC+0.2% M had significant higher respiratory burst activity, PO activity and NOS activity; 0.2% VC+0.4% M had significant higher respiratory burst activity, SOD activity and NOS activity.
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