Investigation Of Calves Viral Diarrhea Related Pathogen Of Large-scale Dairy Farm In Northern Xin Jiang Region

Bovine rotavirus(BRV),Bovine coronavirus(BCV) and Bovine viral diarrhea virus(BVDV) were the main three kinds of pathoens for causing calf diarrhea,its affect the production performance of animal seriously and bring huge economic losses to the development of animal husbandry.North Xinjiang area was the main base of cattle industry,but,the systematic investigation of three kinds of pathogen about calf viral diarrhea has not been reported.Between January 2014 and September 2015,173 feces,intestinal content and serum samples were collected from seven major large-scale dairy farm of northern Xinjiang area such as Shi Hezi,Sha Wan,Kui tun,Bo le,Hu tubi.Among them,there were 125 diarrhoeic calf samples and 48 healthy calf samples at the same age.Reverse transcription polymerase chain reaction(RT-PCR) and Sandwich ELISA method were used to investigate infection situation;sequence analysis was used to analyze the virus genotype,calf diarrhea relatively pathoens were detected from calf samples at the same time.Bovine rotavirus,coronavirus and viral diarrhea virus infection situation were investigated in this region′s large-scale diary farm.This investigation ruselt will provide certain theoretical basis for the prevention calf viral diarrhea related diseases and vaccine development.The research methods and results were as follow:1. Pathogenic investigation of calf diarrhea rotavirus in parts region ofnorthern XinjiangThe results show that 29 positive samples were deteced by ELISA with rate of0~30%.Except positive antigen was not deceted from Hu Tubi`s dairy farm, positive antigen was deceted from others dairy farms.65 positive samples were deteced by method of RT-PCR with rate of 24%~90.91%,only bovine rotavirus antigen were deteced from health calves in Shi hezi`s dairy farm.Nucleotid sequence analyzed result show that I2 genotypes was identified which caused by calf diarrhea from northern Xinjiang region.The virus strains homology with standard strain were above91.4%.This implied that widespread bovine rotavirus infection situation was existed in parts of northern Xinjiang region`s major large-scale dairy farm,and parts dairy farm infection rate was higher.2. Pathogenic investigation of calf diarrhea coronavirus in parts region ofnorthern XinjiangThe results show that 20 positive samples were deteced by ELISA with rate of0~40%. Except positive antigen was not deceted from Hu Tubi`s and Kui Tun`s dairy farm, positive antigen was deceted from others dairy farms,bovine coronavirus werenot deteced from healthy calf.35 positive samples were deteced by method of RT-PCR with rate of 0~60%. Except positive antigen was not deceted from Hu Tubi`s dairy farm, positive antigen was deceted from others dairy farms,bovine coronavirus were not deteced from healthy calves too,this result consistent with the ELISA test result.N gene and S1 gene were analyzed by DNAMAN and DNAStar software,the result show that however,infection of the Xinjiang region of bovine coronavirus was keep the high homology with reference strains,variation was still existed with the characteristics of regional classification.Strains had the close genetic relation in the same area.3. Pathogenic investigation of calf diarrhea bovine viral diarrhea virus inparts region of northern XinjiangELISA and RT-PCR method were used to detect BVDV of Shi hezi`s dairy farm of NO.2 and NO.3 and Bo le`s dairy farm with positive rate of 60%,32%,13.3%;100%,48%,13.3%.The positive BVDV strains sequence analyzed result show that BVDV-1b gene subtype was identified from cloning of 12 strains of BVDV positive strains of the trial.Clone strain had high homology with standard strain Osloss with rate of 97.6~98.3%.