| Mud crab(Scylla paramamosain) is an important marine cultured species in southeast coast of China. However, with the cultivation area and intensity expending, incidence of disease was growing. The diseases, caused by viral, bacterial and parasites, seriously hindered the development of aquaculture. In recent years, Mud crab dicistrovurus-1 and crab reo-virus carry a high rate in farmed and wild mud crab, that are the main pathogens. For viral diseases, there is no effective treatment. Prevention is an important way to reduce the occurrence and economic losses. Herbs can not only sterilize and promote the growth of aquatic animals, but also enhance their immune function and improve disease resistance. In this study, Scylla was soaked with herbal extract water, and the survival rates of Scylla were compared in order to screen antiviral herbs, then the effects of these antiviral herbs on crab immune factors in serum were studied to investigate the mechanism of resistance.First, soaking Scylla with 200 kinds of herbs and screening herbs which could improve the survive rate of Scylla. Selected herbs are: Knotweed, Green suitcase, Elsholtzia, TCS, Guava leaves, Sophora, Plantain, Shegan, Dodder, Prunella, one hundred, Angelica, Radix, gentian, pomegranate rind and even Alice. The survive rate were: 51.1%, 38%, 40%, 56%, 50%, 40%, 42%, 60%, 30%,38%, 40%,40%, 47%, 31%, 42%, 50%, respectively, and the control group was 33%. These herbs improved the survive rate of Scylla except gentian and dodder. From the results of cumulative mortality, the crab in every treatment group started to die on the third day. Virus test results show that there were no virus detected in the group of Guava leaf, plantain and pomegranate rind, which proof that these three herbs could inhibit viral reproduction.Secondly, investigated Scylla immune factors, we found that in the case of shell length and weight has no difference. Fatness Scylla different immune function. farming Scylla’s LSZ、PO、ACP、AKP show significantly with fatness. conform to the law of quadratic equations, S curve equation offerings equation. Then the wild Scylla ‘s SOD significantly with fatness only. consistent with the law logarithmic equation. This can be concluded that farming Scylla has relationship with fatness.Finally. we study the effect of guava leaves, forsythia, TCS and licorice on activities of immune few of immunological factors in the serum of the mud crab by soaking them. Among them, The results showed that the average survival rate of trial group was(52.1±2.6)% and the control group was(32.4±0.6)%. Survival rate was increased by 60.8% than the control group. As the extension of experimental time, the activity of ACP、AKP、LSZ and SOD in serum of the mud crab increased firstly, the decreased and leveled off finally. AKP and LSZ activities of reached maximum at 24 h in the experimental group, which were significantly higher than the control group(P<0.05); ACP and SOD activities reached maximum at 48 h in the experimental group, which were significantly higher than the control group(P<0.05). PO activity had a sharp increasing at 72 h post treatment and was significantly higher than the control group(P<0.05). No significant differences were observed between the experimental and control groups at other sampling time(P> 0.05).The forsythia group’s PO and ACP reached maximum at 48 h, which were significantly higher than the control group(P<0.05),SOD and LSZ reached maximum at 24 h. which were significantly higher than the control group(P<0.05), SOD were not significantly at each time point; TCS group’s ACP and AKP reached maximum at 24 h. which were significantly higher than the control group(P<0.05), LSZ and PO reached maximum at 48 h, which were significantly higher than the control group(P<0.05), SOD were not significantly at each time point. those results shows that different herbs has different effects on Crab immune function.In conclusion, this study screened herbs which can suppress virus propagation, then after investigated Scylla immune factors, we studied the effect of guava leaves, forsythia, TCS and licorice on activities of immune few of immunological factors in the serum of the mud crab by soaking them. Provides theoretical basis for health and disease prevention mud crab farming. |
PDF Full Text Request