MPS And AR In Large-scale Pig Farms In Shandong Province And Research On Immune Prevention And Control Technology

Mycoplasmal pneumonia of swine(MPS)is a chronic interstitial pneumonia,also known as swine asthma,caused by Mycoplasma hyo pneumoniae(Mhp).swine infectious atrophic rhinitis(AR)by bronchial defeated blood wave’s coli(Bordetella bronchisepfica,Bb)and kill Pasteurella(Pasteurella multocida,Pm)infection caused by a chronic respiratory infectious disease,two conditions are difficult to cure bacterial respiratory system disease,pig prevalent in our country,to cause great economic losses in pig.According to the investigation,most large-scale pig farms in shandong province only had one MPS inactivated vaccine immunization at the age of 14 days,and AR was not immunized.In order to understand the current epidemic status of the two diseases in large-scale pig farms in shandong province,evaluate the effect of vaccine immunization prevention and control,and provide theoretical basis for the adjustment and optimization of immunization procedures and comprehensive prevention and control of the two diseases.From 2018 to 2019,throat mucus swabs and nose swabs were collected from large-scale pig farms in some regions of shandong province at all stages to detect the pathogenic infection of MPS and AR.The lungs of slaughtered pigs were randomly examined for ocular and microscopic lesion scores.The nasal lesions of some dead pigs from pig farms were sampled to evaluate the status of AR infection.Isolation culture and drug sensitivity test were carried out on Mhp to determine the sensitive drug of Mhp epidemic strain.In 2019,experimental pig farms were selected to adjust and optimize the immune procedures of MPS and AR respectively,and the above investigation was conducted on the prevalence of the two diseases in the experimental pig farms and compared with the investigation and experimental pig farms in 2018.The results showed that,in the throat mucus swabs,qPCR detection showed that the Mhp infection rate increased significantly after the transfer from conservation to fattening pigs in2018,and the Mhp infection risk was the highest from February to May.Based on this,the MPS immunization program of a certain experimental pig farm in Linyi was adjusted and optimized in 2019.Piglets were injected with live vaccine at 7-day and inactivated vaccine at21-day.The sows were intramuscular injected inactivated vaccine once before breeding with reference to piglet immunization procedure.Then,they were injected inactivated vaccine at 3to 5 weeks before delivery.The results showed that the levels of Mhp antibody in all stages ofthe pigs were maintained at a high level.The overall infection rate reduced 72.23% compared with that before the adjustment,which eliminated the infection risk of transfering from the preserved pigs to the fattening circle.The detection of antibodies of CSFV,PRRSV,PRV gE and PCV2 in the serum of Mhp vaccine immunized pigs at each stage showed that no significant difference was found compared with that of the non-immuned pigs.It indicated that MPS immunity did not affect the immune effect of the vaccine against viral diseases.In2018,lung consolidation was more serious in slaughtering pigs,with the majority of lung consolidation in the apical and cardiac leaves,and the detection rate of lung consolidation was as high as 87.27%(48/55).Hemorrhage and congestion of lung accounted for 67.27%(37/55).Emphysema lesions in the lungs accounted for 12.73%(7/55).In 2019,the detection rate of lung consolidation was 12.70%(8/63),mainly presenting small area consolidation of apical and cardiac leaves,and presenting mild interstitial pneumonia.The drug susceptibility test proved that the Mhp strains which had been prevalent in the past two years had developed resistance to ciprofloxacin,however,high sensitivity to tyromycin,tyromycin,temicol,tetracycline,lincomycin.From 2018 to 2019,some pig farms in Laiwu,Zibo,Jining,Linyi,Weifang and Dezhou were investigated for AR epidemiology.Most of the pig farms were not immunized with AR vaccine.Through autopsy in pig farms and analysis of nasal images,it was found that there were a high proportion of AR infection lesions in dead pigs,and the lesions were mainly at grade 1,accounting for 5.52%(28/507).The proportion of AR infection in pig farms in Jining was the highest,accounting for 11.83%(11/93).Nasal swabs from some pig farms in Jining,Linyi and Laiwu,shandong,were detected by PCR.The results showed that the infection rate of 2-week-old piglets was higher than others.It reached40% in Laiwu(12/30).Two doses of Bb+Pm inactivated vaccine was administered to the piglets at 1 week.Sows were vaccinated in the 6 weeks and 2 weeks before the delivery.The incidence of AR infection in 2-week-old piglets in the three pig farms decreased by 23% on average.Laiwu had the best immune effect,reducing the positive rate of 2-week piglets by26.67%,3-week piglets by 28.57%,and 4-week piglets by 9.33%.In summary,the pig farm carried out MPS immunization procedures: piglets were snorted at 7 days old live seedlings and intramuscular injected at 21 days old inactivated seedlings.Intramuscular injection of inactivated sow before mating;Sows are inactivated by intramuscular injection 3 to 5 weeks before delivery,and boars are exempted from inactivation twice a year.MPS prophylaxis: 2 courses of prophylaxis in accordance with the therapeutic dose of tyromycin and temicox after the pigs were transferred to the fattening zone.AR immunization procedure: piglets 7 days old Bb+Pm combined inactivation of oilspray nose;Intramuscular injection of sows on Tuesday before delivery.It can significantly reduce the incidence of MPS and AR infection and the degree of pulmonary lesions.