The Survey Of Feedstuff Contamination Of Escherichia Coliform And The E. Coli Serotyping And Toxicity Genes Detection Of Beef Cattle Farms In Xinjiang

Beef cattle production is one of the leading animal husbandry industries in Xinjiang. Aksu prefecture in the south of Xinjiang, Yili and Tacheng prefectures in the north of Xinjiang are the main producing areas for beef cattle production. The hygiene and quality situation of feedstuff for beef cattle is strongly associated with that of animal and its products. There is lack of clearly systemic background information about the hygiene and quality of feedstuff for beef cattle in Xinjiang. Therefore the fallowing investigations were conducted in beef cattle farms in the aforementioned prefectures:1. 422 samples of 6 categories of feedstuff, i.e., hull, concentrates, straw, mixed feeds, hay and silage were taken from 5 beef cattle farms in Aksu, Yili and Tacheng prefectures. The coliform bacteria was detected according to the method mandated in the national standard GB/T18869-2002, the changes of the coliform bacteria in the feedstuff were compared between different beef cattle farm locations, seasons and the raising model.2. The feeds samples and fecal samples were also collected from abovementioned farms for E. coli screening, and the multiple serum types of O antigens was detected by using polyvalent O antigen plate agglutination test. The virulence genes of eae、stx1、stx2 were detected by multiplex-PCR method.Results showed that:1. the positive rate of coliform bacteria tested in the feedstuff was 67.0% in general, with the down gradient of 87.8% in the hull, 78.9% in the concentrate, 76.3% in the straw, 73% in mixed feeds and 52.1% in the hay, however negative in the silage; There was certain degree of contamination by coliform bacteria in the feedstuff between farms located both in the north and south of Xinjiang, but showing no difference from point of view of the contaminated level; the positive rate of coliform bacteria in the feedstuff was higher in the summer(58.6%) than in the winter(10%) in the northern beef cattle farms, whereas that in the feedstuff in the southern beef cattle farms was both in high level between the summer and winter. The positive rate of coliform bacteria in the feedstuff was 46.3% in intensive beef cattle farms and 47% in extensive beef cattle farms, there was no any difference.2. 59 strains of E. coli were identified has polyvalent serum type among the 77 strains of in from feed samples. polyvalent serum type O5 and O19 were the advantage type polyvalent serum(detection rate of 11.86%). followed by polyvalent serum antigen O16(10.17%), polyvalent serum antigen O14, O15, O18 also have high rate, more than 6%. 205 strains E. coli isolated from feces, 123 strains have polyvalent serum type, O5 and O6 were strength polyvalent serum type, 13.82% and 10.57% of detection rate. In addition polyvalent O antigen in serum, O4, O13, O14, O17 and O20 contained more than 6%. The virulence gene test showed 48 E. coli strains carrying virulence genes, in which the detection rate of stx1,stx2 and eae was 43.7%, 45.8%and 37.5%, respectively. There was a correlation of polyvalent serum type of O antigen with virulence gene existed. The present study provides basic scientific data for the risk evaluation of feedstuff microbial contamination and hence lays a fundamental base for setting the standard of controlling feedstuff contamination.The overlapping of polyvalent serum type of O antigen and virulence genes between feedstuff and feces origins suggests that the pathogenic E. coli in the feedstuff should be concerned.