Epidemiological Survey Of PRRS In Henan Province And The Application Of Banlangen Granules And Yinhuang Powder On PRRSV

Porcine reproductive and respiratory syndrome(PRRS)is a viral infectious disease caused by the porcine reproductive and respiratory syndrome virus(PRRSV).In recent years,the PRRSV pathogen positive rate in pig farms across Henan has been increasing year by year,seriously threatening the development of pig farms.In this study,we conducted a comprehensive survey of PRRS prevalence in Henan province from January to December 2021 and carried out a study on the application of Banlangen granules and Yinhuang powder on the PRRSV wild virus domestication of gilts,in order to provide a basis for PRRS prevention and control in production.To systematically grasp the situation of PRRSV wild virus infection in PRRS vaccine non-immunized pig farms in Henan Province,8504 serum samples from 485 PRRS vaccine non-immunized pig farms in Henan Province were carried an antibody tested by ELISA.The results showed that the PRRSV antibody positive rate in non-immunized farms in Henan was 70.4%;the antibody positive rate among different regions varied(65.9%-80.1%)in ascending order: South,Central,East,West,and North Henan.The antibody positive rates in different pig stages are different(47.9%-83.0%)in ascending order: weaning pigs,piglets,boars,feeders,sows,gilts.The antibody positive rates among different quarters were also different(61.6%-77.6%)in ascending order: the fourth quarter,third quarter,second quarter,and first quarter.The results showed that PRRSV wild virus infection in non-immunized pig farms was prevalent in all stages and in different quarters in Henan Province.To systematically grasp PRRSV antibody positive rate in PRRS vaccine immunized pig farms in Henan Province,3925 serum samples from 279 PRRS immune pig farms in Henan Province were carried an antibody tested by using the ELISA method.The results showed that the antibody positive rate in PRRS vaccine immunized pig farms in Henan Province was 75.2%;the antibody positive rate among different regions varied(71.9%-78.9%)in ascending order: East,Central,West,South,and North Henan.The antibody positive rates in different pig stages are different(60.9%-87.1%)in ascending order: weaning pigs,piglets,boars,sows,feeders,gilts.The antibody positive rates among different quarters were also different(68.7%-82.8%)in ascending order: the fourth quarter,first quarter,second quarter,and third quarter.The results showed that there were antibody negative pigs in PRRS vaccine immunized farms at different stages,quarters,and regions in Henan province.To understand the PRRS pathogenic situation in Henan’s pig farms,FQ-PCR testing was performed on 1360 diseased materials from clinically suspected cases throughout Henan.The results showed that there were 379 PRRSV pathogen positive samples with a positive rate of 27.9%;PRRSV pathogen positive rates in East,South,West,North,and Central Henan were respectively 19.3%,24.0%,18.0%,38.1%,and36.7%;the PRRSV positive rates from the first to fourth quarters were respectively33.2%,34.3%,12.7%,and 27.2%.The pathogen positive rates of pig groups in different stages also differed(14.1%-36.4%)in ascending order: gilts,sows,feeder pigs,gilts,piglets,and weaning pigs.The results showed that PRRSV infection rates of pig herds in different quarters,regions,and stages in Henan in 2021 were different.To address the problem of PRRS outbreaks in pig herds caused by persistent,recessive toxic carriage and detoxification after PRRSV domestication of gilts in pig farms,40 gilts were randomly divided into experimental and control groups in this study,all of which were infected and domesticated with PRRSV wild virus positive serum.In the experimental group,1.5kg of Banlangen granules and 1kg of Yinhuang soluble powder were added per ton of feed for 15 days after infection,while the feed was left untreated in the control group,so that durations of PRRSV antibodies and viraemia in the pigs before and after the test were measured.The results showed that the pigs in both experimental and control groups were PRRSV antibody positive before the test,with no significant difference(p﹥0.05).After the test,the antibody S/P values increased in both groups,and the corresponding immune responses occurred in both groups.After 7 days,14 days,21 days,28 days,and 35 days of PRRSV wild virus serum domestication,the PRRSV pathogen positive rates in the experimental groups were 100%,50%,25%,0%,and 0% respectively,and the PRRSV pathogen positive rates in the control group were 100%,60%,35%,20%,and10% respectively.The results showed that the viraemia in the experimental group had completely disappeared after 28 days of domestication,while in the control group,10% of the pigs were still in the viraemic phase at the end of the whole observation period.The results showed that the antibody S/P values were higher in the experimental group than in the control group with significant differences(P<0.05),indicating that the addition of Banlangen granules and Yinhuang powder to the diet can shorten the duration of viremia after PRRSV wild virus serum domestication,improve the pigs’ immune response ability,and reduce the risk of continued viral carriage,detoxification,and dispersal after wild virus domestication of gilts.