Shrimp Immune Enhancer And Application

A series of experiments were conducted to investigate the application of immunostimulants on Chinese shrimp Fenneropenaew chinensis larvae, the screening and application of compound immunostimulants on pacific white shrimp Litopenaeus vannamei, and the possible mechanism. The results are summarized as follows:(1) A review for crustacean immunity and current status of immunostimulants(2) The zoea-stage and mysis-stage larvae of Chinese shrimp Fenneropenaeus chinensis were immersed in 5 different concentrations of p-glucan suspension (0, 0.1, 0.3, 0.5 or Img/ml ) for 3 h, then culured normally for 48 h. Each immersion concentration was assigned to six replicate cone flasks. On 48 h after normal culture, larvae from triplicate flasks were challenged with Vibrio parahaemolyticm at a concentration of 5.9 106 cfu/ml for 48 h. The other triplicate flasks were under normal culture for another 48 h. Deaths were recorded after experimental infection, and growth and development index (DI) of larvae were examined when the second 48 h of normal culture was ended. Significantly higher survival rate was observed in zoea-stage larvae treated with 0.1, 0.3 and 0.5mg/ml glucan, in mysis-stage larvae treated with 0.3 and 0.5mg/ml glucan than that of larvae treated with 0 or 1 mg/ml glucan. Significantly enhanced growth and DI were observed in zoea-stage larvae treated with 0.3 and 0.5mg/ml glucan, but no significant enhanced growth and DI were observed in mysis-stage larvae. It therefore appears that p-glucan can be used as immunostimulant for shrimp larvae, and the concentration of 0.3-0.5 mg/ml was recommended when treated by immersion.(3) The P-glucan was administered orally at 4 concentrations (0.00%, 0.10%, 0.25% and 0.50% of dietary dry matter)for 10 days. Each diet was randomly assigned to triplicate tanks, and each tank was stocked larvae at the density of 100 L-1. The results showed significantly higher DI was observed in larvae fed glucan-containing diets than that of glucan-free diet (P<0.05) at 14 dph; Survival rates, body lengths and specific growth rates (SGR) of larvae fed glucan-0.25% and glucan-0.50% were significantly higher than that of larvae fed glucan-free diet (P<0.05) at 14 dph. Immune parameters, such as phenoloxidase (PO), superoxide dismutase (SOD), acid phosphatase (ACP) and alkaline phosphatase (ALP) of larvae were examined at 9 and 14 dph. The results suggested that these immune parameters could be improved byp-glucan, although not always significant. A pathogenic challenge test by V. parahaemolyticus at 14 dph showed that significantly higher cumulative mortality was observed in larvae fed glucan-free diet compared with those fed the glucan-containing diets (/><0.05). Since the highest values for different parameters examined were always observed in larvae fed glucan-0.25% diet, the supplementation of |3-glucan to microbound diet at concentration of approximately 0.25% is recommended for the culture of shrimp larvae.(4) The p-glucan was administered orally at concentrations 0.25% of dietary dry matter, which were fed to the larvae in different feeding schedules: DO (permanently control diet); Dl (permanently 0.25% glucan diet); 3D1-3DO (three days with 0.25% glucan diet-three days with control diet); 1D1-3DO (one day with 0.25% glucan diet-three days with control diet) . So there were 4 treatments and each treatment was randomly assigned to triplicate tanks, and each tank was stocked larvae at the density of 100 L'1.The results showed that survival rate, DI, body length and SGR of larvae fed glucan-0.25% diet were higher than those of larvae of other three groups, although not always significant. Immune parameters, such as PO, SOD, ACP and ALP of larvae were examined at 9 and 14 dph. The results suggested that these immune parameters of larvae fed glucan-0.25% diet were higher than those of larvae of other three groups, although not always significant. A pathogenic challenge at 14 dph showed that cumulative mortality for glucan-0.25% diet treatment was significantly higher than glucan-f...