Studies On High Performace Immunostimulants For White Shrimp Litopenaeus Vannamei And Sea Cucumber Apostichopus Japonicus Selenka

Six feeding trials were conducted in indoor circulating system to investigate the effects of dietary glycyrrhizin, soybean isoflavones, levamisole, nucleotide and bovine lactoferrin on growth, non-specific immunity and disease resistance for shrimp (L. vannamei) and sea cucumber (A. japonicus Selenka). The results are summarized as follows:1. The growth response, total haemocyte count (THC), respiratory burst (release of superoxide anion), phenoloxidase (PO), superoxide dismutase (SOD), nitric oxide synthase (NOS) as well as resistance to the pathogen V. alginolyticus were measured in shrimps which had been fed diets supplemented with glycyrrhizin at 0, 50, 100, 150 and 200 mg kg-1 diet for 8 weeks. Dietary glycyrrhizin had no significant influence on survival rate of the shrimps (P>0.05). Significantly higher SGR was observed in the treatments with dietary glycyrrhizin supplementation than that in control (P<0.05). However, no significant differences in body composition were noticed among dietary treatments (P>0.05). Shrimps fed the diet with 200 mg kg-1 glycyrrhizin had significant higher THC, PO activity, respiratory burst activity and SOD activity than that in control (P<0.05). Increased THC, respiratory burst activity and NOS activity were also noticed in shrimps fed diets with 100 or 150 mg kg-1 glycyrrhizin (P<0.05). Significantly lower cumulative mortality after challenge was observed in shrimps fed the diets supplemented with glycyrrhizin (8.33 -16.67%) than that in control group (36.67%) (P<0.05). These results indicated that glycyrrhizin might elevate the function of nonspecific immunity and enhance disease resistance of L. vannamei as well as improve production in shrimp farming. 2. The growth response, total haemocyte count (THC), respiratory burst (release of superoxide anion), phenoloxidase (PO) activity, superoxide dismutase (SOD) activity, nitric oxide synthase (NOS) activity and resistance to the pathogen Vibrio alginolyticus were measured in the white shrimp (L. vannamei) which had been fed diets supplemented with soybean isoflavones (SI) at 0, 5, 10, 20, 40 mg kg-1 for 8 weeks. Dietary SI had no significant influence on survival rate of the shrimps (P>0.05). Significantly higher SGR was observed in treatments with 10, 20 and 40 mg kg-1 SI supplement than that in control (P<0.05). No significant differences in body composition were noticed among dietary treatments. Shrimps fed a diet with 20 mg kg-1 SI supplementation showed significant increase in THC, PO activity, respiratory burst activity, SOD activity as well as NOS activity (P<0.05). Increased THC, respiratory burst activity, SOD activity and NOS activity were also noticed in shrimps fed the diets with SI supplementation at 10 or 40 mg kg-1 (P<0.05). Significantly lower cumulative mortality after challenge with V. alginolyticus was observed in shrimps fed the diets with SI supplementation (10.0-13.3%) than that in control group (36.7%) (P<0.05). It is therefore concluded that oral administration of SI at 20 mg kg-1 for 8 weeks could enhance the immune ability of shrimps and improve production in shrimp farming.3. An 8-week feeding experiment was conducted to evaluate the effects of glycyrrhizin on growth, non-specific immunity of sea cucumber (A. japonicus Selenka) as well as its resistance against V. splendidus. Glycyrrhizin was administered to sea cucumbers through the diets at four levels (0, 50, 100 and 200 mg kg-1 diet, respectively). The basal diet (0 mg kg-1 diet) was used as the control. Each diet was randomly allocated to triplicate groups of sea cucumbers in indoor fiberglass (200 l) tanks with circulating seawater and constant aeration. And each tank was stocked with 30 sea cucumbers (initial average weight 6.80±0.10g). The results showed that dietary glycyrrhizin had no significant influence on survival rate of sea cucumber. Glycyrrhizin supplemented at 200 mg kg-1 significantly enhanced the specific growth rate of sea cucumbers (P<0.05), whereas other supplementation did not (P>0.05). No significant difference in body composition was observed among dietary treatments. Sea cucumbers fed diet with 200 mg kg-1 glycyrrhizin had significantly higher nitric oxide synthase (NOS) activity and lysozyme (LZM) activity than that fed other diets(P<0.05). The intracellular O2- production (COP), LZM, NOS, superoxide dismutase (SOD) and acid phosphatase (ACP) activity in sea cucumbers fed diets with 100 and 200 mg kg-1 glycyrrhizin were significantly higher when compared with the control and 50 mg kg-1 supplementation groups (P<0.05). However, no significant difference of the above immunological parameters was observed between the control and 50 mg kg-1 glycyrrhizin groups (P>0.05). The challenge experiment showed that sea cucumbers fed the diet with 100 and 200 mg kg-1 glycyrrhizin had significantly lower accumulative morbidity compared with the control and 50 mg kg-1 supplementation groups (P<0.05). And no significant difference was observed between 100 and 200 mg kg-1 supplementation groups. These results suggested that feeding glycyrrhizin at a dose of 200 mg kg-1 could enhance growth, non-specific immunity as well as resistance against V. splendidus of sea cucumber (Apostichopus japonicus Selenka).4. An 8-week feeding experiment was conducted to evaluate the effects of dietary levamisole on growth, non-specific immunity as well as resistance against V. splendidus of sea cucumber (A. japonicus Selenka) (initial body weight 6.80±0.01 g). Results showed that dietary levamisole has no influence on survival rate of A. japonicus (Selenka) (P>0.05). The specific growth rate (SGR) in sea cucumbers fed diet with 0.04% levamisole was significantly increased when compared with the control group (P<0.05). However, no significant difference in SGR was oberved among 0.01%, 0.02% and the control groups (P>0.05). Dietary levamisole had no significant influence on body composition of A. japonicus (Selenka) (P>0.05). Significantly higher intracellular O2- production (COP), lysozyme (LZM) activity, superoxide dismutase (SOD), nitric oxide synthase (NOS) activity and acid phosphatase (ACP) activity in coelomocyte were observed in sea cucumbers fed the diet with 0.04% levamisole when compared with control group (P<0.05). Increased SOD activity and ACP activity were also noticed in sea cucumbers fed diet containing 0.02% levamisole (P<0.05). The SOD activity and ACP activity in sea cucumbers fed a diet containing 0.04% levamisole were showed significantly higher when compared with the other treatments (P<0.05). After 8 weeks of feeding trial, a challenging test was conducted by injecting the sea cucumbers with Vibrio splendidus. Significantly lower (P<0.05) cumulative morbidity was observed during the following 14 days after challenge in sea cucumbers fed the diet containing 0.04% levamisole than that in the control group. The presents results suggested that 0.04% levamisole supplementation in diet could improve growth, non-specific immunity and disease resistance of sea cucumber.5. An 8-week feeding trial was conducted to evaluate the effects of dietary nucleotide on growth, non-specific immunity and disease resistance against V. splendidus of sea cucumber, A. japonicus (Selenka). Nucleotide (GMP) was administered to sea cucumbers through the diets at four levels (0%, 0.03%, 0.06% and 0.12%, respectively). The basal diet (without nucleotide supplementation) was used as control. Each diet was allocated to triplicate groups of sea cucumbers stocked in indoor 200 l circular fiberglass tanks with circulating seawater and constant aeration. And each tank was stocked with 30 sea cucumbers (initial weight 6.80±0.00 g). The results of the feeding trial showed that dietary nucleotide had no significant influence on survival rate of A. japonicus (Selenka). Sea cucumbers fed diets containing 0.06% or 0.12% nucleotide proved to have a significantly better growth than those fed the diet supplemented with 0.03% nucleotide (P<0.05). No significant difference in body composition was observed among dietary treatments. Sea cucumbers fed the diet containing 0.06% dietary nucleotide showed a significant (P<0.05) increase in intracellular O2- production (COP), lysozyme (LZM) activity, superoxide dismutase (SOD), nitric oxide synthase (NOS) activity as well as acid phosphatase (ACP) activity in coelomocyte. Increased LZM activity and SOD activity were also noticed in sea cucumbers fed the diet supplemented with 0.12% nucleotide (P<0.05). No significant difference in the above immune parameters was observed between sea cucumbers fed control diet and fed diet with 0.03% nucleotide supplementation (P>0.05). The challenge trial showed that sea cucumbers fed the diets with 0.06% and 0.12% nucleotide had significantly lower cumulative morbidity compared with the control and 0.03% nucleotide groups (P<0.05), and no significant difference was observed between 0.06% and 0.12% nucleotide groups. These results suggested that feeding nucleotide at a dose of 0.06% could enhance growth, non-specific immunity as well as resistance against V. splendidus of sea cucumber Apostichopus japonicus Selenka.6. An 8-week feeding experiment was conducted to evaluate the effects of bovine lactoferrin (LF) on growth as well as non-specific immunity of sea cucumber (Apostichopus japonicus Selenka). Lactoferrin was administered to sea cucumber through the diets at three levels (50, 100 and 200 mg kg-1 diet, respectively). The basal diet (without lactoferrin supplementation) was used as the control diet. The intracellular O2- production (COP), lysozyme (LZM) activity, superoxide dismutase (SOD), nitric oxide synthase (NOS) activity and acid phosphatase (ACP) activity in coelomocyte were measured at day 56. And the specific growth rate (SGR), survival and cumulative mortality after body injection with V. splendidus (100μl V. splendidus suspension at 1×109CFU ml-1 per sea cucumber) were assayed after 56 days feeding period. Dietary lactoferrin had no significant influence on survival rate of sea cucumber. Significantly higher SGR was observed in sea cucumber fed diet containing 100 mg kg-1 lactoferrin than that in control diet. No significant difference in body composition was observed among dietary treatments. Sea cucumbers fed the diet containing 100 mg kg-1 lactoferrin showed significant increase in COP, NOS activity, SOD activity, LZM activity as well as ACP activity (P<0.05). Increased NOS activity, SOD activity and ACP activity were also noticed in sea cucumbers fed the diet containing 200 mg kg-1 lactoferrin (P<0.05). Sea cucumbers fed the diet containing 100 mg kg-1 lactoferrin showed significantly higher LZM activity when compared with other treatments (P<0.05). The highest cumulative morbidity was observed in the sea cucumbers fed the control diet when challenged with injection of V. splendidus. Significantly lower cumulative morbidity at 14 days after challenge was observed in sea cucumber fed diets containing 100 or 200 mg kg-1 lactoferrin compared with the control (P<0.05). These results indicated that lactoferrin might elevate the function of nonspecific immunity and enhance disease resistance of A. japonicus (Selenka) as well as improve production in sea cucumber farming.