| Porcine reproductive and respiratory syndrome(PRRS)is characterized by reprodu ctive failures in late-term pregnant sows,high mortality in unweaned piglets and respi ratory problems in pigs of all ages.The clinical syndrome includes: difficulties breathi ng of piglets and sows reproductive disorder(infertility,abortion,mummy and weakly piglets).PRRSV caused a great economic loss in pork production industry.Pigs infect ed with PRRSV could reduce immunity and increase susceptibility to other pathogeni c factor.At present,vaccine was used to protect the pigs from the PRRSV infection.T he vaccine has two kinds(inactivated vaccine and live virus vaccine).Inactivated vac cine is safety but cannot stimulate cell immunity and antibody dependence enhanceme nt(ADE)may cause long-term persistent infection in infected pigs.Mortified live vir us vaccine can induce more effective immune response than killed virus,but the safet y aspect is still arguing in academia.Therefore,it is particularly important to find a m ethod which can enhance the immune effect and reduce pigs residual poison.Polysaccharides can improve animal immunity and production performance.In this study,residual poison and immune-regulating abilities of astragalus polysaccharides were investigated through a series of experiments.Preliminary exploring the immunor egulatory effects of astragalus polysaccharides and offered the theory basis for develo ping polysaccharides as immunopotentiators.1.Effect of APS on PRRSV antibody in the serum of immunized pigs.Purpose: studying astragalus polysaccharides on the influence of live PRRSV vacci ne immune antibody.Method: using astragalus polysaccharides and live PRRSV vaccine to immune pigs.Blooding at different time points.Using ELISA for detecting PRR SV antibody levels.Results: astragalus polysaccharides as an immune regulator,it can improve the antibodies level and make antibodies level stable later.2.Effect of APS on PRRSV titer in the serum of immunized pigsPurpose: measuring the nucleic acid load change of the pigs feeding with astragalus polysaccharides.Method: Blooding at different time points before and after immuniz ation.Using Real-time PCR for detecting the change of PRRSV residue.Result: Contr ol group PRRSV virus nucleic acid load present a tendency of increasing loads.Exper imental group PRRSV virus nucleic acid load mostly present a downward trend.Astra galus polysaccharides can effectively reduce load of PRRSV virus nucleic acid in the blood,purify PRRSV residual poison in the blood and improve state of health in swin ery.3.Effect of APS on weaning pig growth performancePurpose: studying the influence of astragalus polysaccharides on weaning piglet gro wth performance.Method: Selecting of weaned piglets and dividing into 2 groups ran domly.Experimental group feeding astragalus polysaccharides with radix isatidis parti cle and silver yellow soluble powder.Blank control group feeding fundamental feed.Recording the performance index and the incidence of disease of weaning piglets.Res ult: The average daily gain of treatment group is higher than the control group and the comprehensive incidence is lower than the control group. |
