| Hu sheep has become a breed that has been introduced all over the country because of its excellent traits.With the establishment of large-scale Hu sheep farms in recent years,Hu sheep respiratory infectious diseases occur frequently,especially sheep pneumonia,which seriously restricts the development of Hu sheep breeding industry.In this study,the microbial diversity of the upper and lower respiratory tracts and lungs of Hu sheep with pneumonia was analyzed by high-throughput sequencing of 16 S r RNA,and then epidemiological investigation was carried out on the respiratory pathogens of Hu sheep farms in some counties and districts of Yulin City,and finally mycoplasma isolation and identification were carried out.In thses three aspects above,the respiratory pathogens of Hu sheep in Yulin City were studied,and the results can provide scientific basis for the prevention and control of Hu sheep pneumonia.1.After sterile necropsy of 3-month-old Hu sheep showing symptoms of respiratory tract infection in a large-scale Hu sheep farm in Yulin City,mucus cotton swabs and lung tissues were collected from the upper and lower respiratory tracts,and DNA was extracted;through the variable v4 of the 16 S gene PCR amplification,library construction and computer sequencing were carried out in the region.Finally,the microbial communities of the upper respiratory tract and lower respiratory tract lung tissue of Hu sheep were analyzed through OTUs clustering,species composition analysis,species diversity analysis and searching for marker species.The results showed that the upper and lower respiratory tracts of Hu sheep with respiratory infectious diseases collected in the experiment had abundant microbial groups,and the number of species was similar.In particular,the lung tissue also exhibited a large number of microorganisms at the same time,and it was found that mycoplasma microorganisms accounted for a certain proportion.The results indicated that the Hu sheep involved in this study may be infected by mycoplasma,suffering from mycoplasma pneumonia and secondary to abnormalities in the distribution and ecology of other microorganisms.2.Based on the results of the analysis of respiratory microflora in Hu sheep with pneumonia,483 nasal swabs were collected from six counties and districts of Yuyang District,Suide County,Dingbian County,Wubao County,Mizhi County and Qingjian County,and the infection of Mycoplasma ovipneumoniae,Mycoplasma capricolum subsp.capricolum,Mycoplasma capricolum subsp.capripneumoniae,Mycoplasma mycoides subsp.Mycoides,Mycoplasma mycoides subsp.capri and Mycoplasma arginini was investigated by specific PCR.The results showed that mycoplasma infection was found in different degrees in the other 5 surveyed counties except Qingjian County.Generally speaking,Mmm and Movi were the most infected,with positive rates of 14.08% and 6.21%,respectively.Mmc 1.45%,Mcc 0.21%,Marg0.83%.However,the types and positive rates of mycoplasma infection were different in different counties and districts,among which Yuyang District had the highest positive rate,and the positive rates of Mmm and Movi reached 44.35% and 22.58%;The four mycoplasma involved in this study were detected in Dingbian County which were Movi,Mmc,Mmm and Marg and the positive rates of Mycoplasma were 0.66%,2.33%,2.66%,and 1.33% respectively;Hu sheep in Wubao County and Mizhi County were only detected with Mmm with a positive rate of 25%;only one case in Suide County was infected with Mccp.goat pneumonia,with a positive rate of 5.00%.The results of the study showed that there was a high rate of mycoplasma infection in large-scale Hu sheep farms in Yulin City.Therefore,on the basis of clarifying the infection of mycoplasma,the isolation,culture and identification of the corresponding mycoplasma will be one of the basic tasks for the prevention and control of pneumonia in large-scale Hu sheep farms.3.In this study,positive samples of lamb lung tissue and epidemiological investigation of pneumonia in a Hu sheep farm in Yulin were collected aseptically,and isolated culture,bacterial morphology and colony morphology were identified after smear Gram staining microscopy,PCR detection,and strain identification of isolates by PCR detection and sequencing.The results showed that no bacteria were observed on smear Gram staining microscopy,and PCR tests were only positive for mycoplasma nucleic acid,and negative for the rest of the pathogenic nucleic acid.The isolate was negative for Gram staining,the bacteria were pleomorphic,and typical omelet-like colonies with a "central umbilicus" were formed on PPLO solid medium;PCR species identification of the isolates showed that the primer amplification products of Mycoplasma and Mycoplasma arginine were as expected,and the sequencing results of the Mycoplasma arginine primer amplification products were100% similar to the sequence similarity of Mycoplasma arginine in Genebank.Therefore,it is Mycoplasma arginine that is clearly isolated.In this study,through the analysis of the microbial communities of upper and lower respiratory tract and lung tissues of Hu sheep with respiratory infection symptoms,the epidemiological investigation of Mycoplasma in large-scale Hu sheep farms,and the isolation and identification of Mycoplasma arginine,it was clarified that one of the key pathogens of respiratory tract infection in Hu sheep farms in Yulin City was Mycoplasma,and in addition to conditional Marg infection,Movi,Mcc,Mccp,Mmm,Mmc and Marg had a high pathogenic rate.This study laid a biological foundation for the etiology of respiratory infectious diseases in Hu sheep,and also provided a reference for the prevention and control of respiratory infectious diseases in large-scale Hu sheep farms in Yulin City. |
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