In Vitro Bacteriostatis Chinese Herb Compound Selection For Acute Hepatopancreas Necrosis Syndrome In Litopenaeus Vannamei

Litopenaeus vannamei was one of the three most important farmed shrimp species in the world. New aquaculture models mainly included high density breeding and intensive breeding. The excessive growth of raising speed caused a series of problems, and the most serious problem was disease, which brought huge losses to aquaculture industry. People tended to choose antibiotic drugs to treat disease, this action caught drug residue, threated the health of humans and caught widespread attention to food safety. Chinese herbals were becoming safe alternative to antibiotics with its own characteristics and the advantage of non-toxic. Researching and developing Chinese herbals for aquaculture were the current hot spot. This thesis studied Chinese herbal compounds which had better bacteriostatis than others for the major six pathogens of AHPND in Litopenaeus vannamei. It also studied this Chinese herbal compound whether was safety and had immune effect to Litopenaeus vannamei.This study determined the bacteriostasis of 24 kinds of Chinese herbals for six AHPND pathogens( V. parahaemolyticus、V. Metschnikovii、V. Alginolyticus、V. Harveyi、Vibrio.sp.Ex-25、Aeromonas hydrophila) in Litopenaeus vannamei. The results showed that Sanguisorba officinalis L.、Terminalia chebularetz、Thalictrum simplex、F. mume had batter bacteriostasis effect than the other ones, their average minimum bacteriostatic concentration(MIC) were < 6.38 mg/ml、6.38 mg/ml、11.98 mg/ml、7.68 mg/ml, and the average minimum bactericidal concentration(MBC) were > 25 mg/ml, 19.27 mg/ml, > 25 mg/ml, 16.15 mg/ml. According to orthogonal experiment, these four kinds of Chinese herbal were designed 16 kinds of compounds, compounds had batter bacteriostatic effect with biggeer bacteriatisis circle and lower MIC、MBC. The maximum bacteriostatic circle diameter was 22.08 mm, the average lowest average MIC was 2.67 mg/ml, and the average lowest MBC was 6.90 mg/ml. Comprehensive above, the bacteriostatic effect of HD-4 compound was more significant than other compounds, and the best quality ratio with Sanguisorba officinalis L.: Terminalia chebularetz: Thalictrum simplex: F. mume=1:4:4:4.The research designed 8 groups with different doses of HD-4, proportion of HD-4 from 40, 000 mg to 639 851mg/Kg. The study determined the safety of HD-4 compound with feeding mixed through oral. Results showed that LD50 of compound HD-4 to Litopenaeus vannamei in 120 h was(138537.17±4881.93) mg/Kg, according to the toxicological evaluation criteria, HD-4 compound was non-toxic(LD50>10000 mg/Kg means non-toxic). Weight gain results indicated that the trend were raised first and lowed then from 1 to 8 group. Weight gain rates of the first five groups within 120 h were between 20% ~ 30%, which had significant difference with 6、7、8 groups(P<0.05). Weight gain rates of the later groups slowed significantly, especially the group of 8,whose weight gain rate within 120 h was less than 5%.Litopenaeus vannamei were fed with basal diet supplemented 0.5%、1%、2% HD-4 compounds respectively. Control group was fed with basal diet, but without herbs. While the positive control group’s diet supplemented 1% Yeast cell wall polysaccharides. The activities of ACP、AKP、SOD and LSZ in serum were determined every 5 days after feeding. Then research the weight changes of tested shrimp during 30 days and study the influence of herbal compounds on shrimp organization structure, finally determined RPS through infection experiments. The results found that the activity of AKP fed with 2% HD-4 were enhanced significantly, better than control group on 15 th and 20 th days(P<0.05). The activity of AKP fed with 1% HD-4 enhanced remarkably compared to control group on 20 th day(P<0.05). The activity of ACP fed with 1% HD-4 were enhanced significantly, better than control group on 10 th and 15 th days(P<0.05). The activity of ACP fed with 2% HD-4 enhanced remarkably compared to control group on10thday(P<0.05).The activity of SOD and LSZ fed with HD-4 did not produce significant change compared to control group. With the increase of HD-4 adding, achieved the relative weight gain rate and the specific growth rate was also associated with increased, The best group was 2% HD-4 group which the weight gain rate was(69.71±0.09) % and the specific growth rate was(13.3±2.1)%. Regression curve showed that adding 2.39% HD-4 would gain the highest rate of weight gain. Artifical infection results with adding 0.5%、1%、2% HD-4 groups were showing certain immune protection function, the immune protection gate respectively(23.33±6.67) %,(30.00±10.00) %,(46.67±6.67) %. Tissue section results found that HD-4 for all achieved in hepatopancreas and midintestine tissue did not produce damage.