| Calf diarrhea is one of the common diseases in the growth stage of calves,and more than 50% of the mortality rate of calves before weaning is related to diarrhea,which restricts the economic benefits and healthy development of Xinjiang’s cattle breeding industry.The causes of calf diarrhea are complex,with diarrhea caused by infectious pathogens being the most serious.Common causes of diarrhea in calves include bovine coronavirus(BCo V),bovine rotavirus(BRV),bovine viral diarrhea virus(BVDV),bovine norovirus(BNo V),Escherichia coli,Salmonella,Cryptosporidium parvum,etc.In this study,the main infectious pathogens of calf diarrhea in some Angus cattle farms in southern Xinjiang were investigated,and the detected pathogenic bacteria were analyzed by susceptibility tests,the main viral pathogens were analyzed in genetic sequences,and corresponding prevention and control measures were proposed.In order to provide strong support for the prevention and treatment of calf diarrhea and the development of healthy breeding in Xinjiang.This study is as follows:1.In order to investigate the four-season epidemic of Angus calf diarrhea in southern Xinjiang,in2021,363 samples of calf feces with clinical symptoms of diarrhea were randomly collected from some Angus cattle farms in southern Xinjiang.Samples collected are tested using RT-PCR technology.A total of5 pathogens were detected.The detection rates of BCo V,BNo V,BRV,BVDV,and Shiga toxin-producing Escherichia coli(STEC)were 36.09%,25.07%,9.37%,2.75%,and 21.76%,respectively.BCo V has the highest rate of infection.In this study,calf diarrhea was dominated by single pathogen infection,while mixed infection was dominated by two pathogenic mixed infections.Calf diarrhea infected by viral pathogens is mainly concentrated in autumn and winter,and STEC is mainly concentrated in summer.The causes of diarrhea in calves are different in different seasons and fields.For the detected STEC,15 commonly used clinical antibiotics were used for susceptibility testing,and pathogens are only sensitive to7 antibiotics: amoxicillin,ceftiofur sodium,cefepime,neomycin,enrofloxacin,ciprofloxacin and kanamycin,which can be used as sensitive drugs for the prevention and treatment of bacterial diarrhea in calves in the region.According to the results of the previous investigation,the principle of prevention as the mainstay and prevention and control as the supplement is proposed,and according to the epidemic characteristics of calf diarrhea in different field areas,a high-energy oral rehydration salt program is provided,and corresponding prevention and control suggestions such as establishing isolation areas and doing a good job in disinfection are given.2.The three pathogen-positive samples with high detection rates(BRV,BCo V,BNo V)were amplified and cloned into the p GEM-T vector,and the recombinant plasmid was sequenced with the BRV VP7 gene,BCo V N gene and BNo V VP1 gene reference sequences included in the Gen Bank database for nucleotide and amino acid similarity analysis,and the evolution tree was constructed.The results showed that the BRV detected this time was in the same branch as the Chinese MN928490 reference strain,and the MF940666 found in Korea is farther on the evolutionary tree,while the BCo V was in the same branch as the Chinese MW711287 and MK903505 reference strains,and the similarity with foreign reference strains was also high,and the BNo V was in the same branch as the MZ573179 reference plant found in China.Homology is higher,at 92.9%,the lowest homology compared to the EU794906 strain found in Turkey,at 85.2%,and is farther on the evolutionary tree.In summary,through the investigation of the main infectious pathogens of Angus calf diarrhea in the southern Xinjiang region of Xinjiang,it was found that the main pathogens causing calf diarrhea were BRV,BCo V,BNo V and STEC.In the prevention and treatment of this disease,first establish isolation areas,do a good job of disinfection,and secondly,can be treated with high-energy oral rehydration salts and sensitive drugs.Due to the large number of viral genotypes and the difficulty of vaccine research and development,genetic evolutionary analysis was carried out for the three main viral pathogens,and the genotype of the conservative sequence of BRV,BCo V and BNo V circulating strains in southern Xinjiang was determined,which provided a preliminary reference for disease prevention and vaccine research and development in the region,and helped the prevention and treatment of calf diarrhea and the development of healthy breeding in southern Xinjiang. |
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