新疆部分集约化肉牛养殖场饲料大肠杆菌污染调查及大肠杆菌分型和毒力基因检测

发布时间：2018-07-23 10:46

【摘要】：肉牛养殖业是新疆畜牧业的主导产业之一,南疆阿克苏地区和北疆伊犁、塔城地区是新疆肉牛养殖业的主产区,南疆肉牛养殖主要以农区养殖模式为主,而北疆大多采用暖季放牧冷季舍饲的养殖模式。饲料等养殖投入品的卫生质量与畜产品质量安全关系密切,但新疆肉牛养殖业中饲料卫生质量特别是受微生物污染状况缺乏系统研究,背景不清,为了解南北疆地区肉牛饲料卫生状况,本研究开展了如下研究:1.以阿克苏地区、伊犁和塔城地区肉牛养殖场为对象,采集了秕壳、精料、秸秆、混合饲料、干草、青贮等6大类饲料及原料样品共422份,按照中华人民共和国国家标准GB/T18869-2002规定的饲料中大肠菌群的测定方法,对其进行了测定,并对不同地区(南、北疆)、不同季节(冬、夏两季)和不同养殖模式(集约化养殖、个体散养户)饲料大肠杆菌污染进行了比较。2.采集上述肉牛养殖场饲料、粪源样品进行大肠杆菌分离鉴定,采用多价O抗原平板凝集试验进行多价血清型分型,并进一步采用多重PCR方法对其毒力基因(stx1、stx2、eae)进行了检测分析。实验结果如下:1.饲料大肠菌群总体阳性检出率为67.0%。各类饲料的阳性率从高到低依次是:秕壳类87.8%、精料类78.9%、秸秆类76.3%、混合饲料类73%、干草类52.1%、青贮料为阴性;从南北疆不同肉牛养殖场比较而言,主要饲料及其原料均呈现不同程度的大肠菌群污染,南北疆之间污染程度无可比性;从季节方面,北疆牛场夏季饲料样品中大肠菌群总阳性检出率为58.6%,冬季为10%,夏季污染大于冬季。而南疆夏季肉牛饲料大肠菌群总阳性检出率为44.7%,其中以精料、秸秆的阳性检出率最高,二者均超过50%。而南疆冬季肉牛饲料大肠菌群平均阳性检出率为64%,其中以混合饲料和精料为最高,二者也均超过50%。南疆肉牛养殖场不同季节的饲料大肠菌群污染都较高;从不同养殖模式比较而言,集约化肉牛场与散养模式间的饲料大肠菌群平均阳性检出率分别为46.3%和47%,无明显差异,但从共同拥有的饲料原料看,前者的精料污染较重,而后者的干草污染较重。2.从饲料样品中分离鉴定出的77株大肠杆菌中有59株鉴定出多价血清型,优势多价血清型有O5和O19(检出率均为11.86%),其次是多价抗原血清O16(10.17%),此外多价O抗原血清O14、O15、O18较多,检出率6%。而从粪源分离鉴定出的205株大肠杆菌中有123株鉴定出多价血清型,优势多价血清型有O5和O6,检出率分别为13.82%和10.57%,此外多价O抗原血清型O4、O13、O14、O17、O20较多,检出率均5%;毒力基因检测结果显示48株大肠杆菌携带毒力基因,其中毒力基因stx1的检出率是43.7%,毒力基因stx2的检出率是45.8%,毒力基因eae的检出率为37.5%。分析比较发现O抗原多价血清型与大肠杆菌毒力基因之间存在着相关性。比较养殖场中饲料源和粪源大肠杆菌的多价血清和毒力基因发现彼此有交叉重复,需要重视饲料中致病性大肠杆菌的污染。本研究结果为肉牛饲料微生物污染风险评估提供了科学数据,为肉牛饲料微生物污染限量标准制定奠定了基础。
[Abstract]:Beef cattle breeding is one of the leading industries in Xinjiang animal husbandry. Akesu area in southern Xinjiang and Yili in Northern Xinjiang and Tacheng are the main producing areas of beef cattle breeding in Xinjiang. The quality and safety of the products are closely related, but the lack of systematic research on the quality of feed hygiene in Xinjiang beef cattle breeding industry, especially by microorganism pollution, is not clear. In order to solve the health status of beef cattle feed in the southern and northern areas, the following study was carried out in this study. 1. the cattle farms in Akesu area, Yili and Tacheng area were collected as the object. 6 major types of feed and raw materials, such as husks, fine materials, straw, mixed feed, hay and silage, were measured in 422 parts. According to the determination method of coliform in the feed of People's Republic of China national standard GB/T18869-2002, it was determined in different areas (south, North Xinjiang), different seasons (winter, summer two season) and different culture mode (Intensive Culture). The feed of Escherichia coli in feed was compared with.2.. The animal feed was collected and the fecal samples were isolated and identified. The multivalent O antigen flat agglutination test was used to classify the multivalent serotype, and the multiple PCR method was used to detect the virulence gene (stx1, Stx2, EAE). The results are as follows: 1. the positive rate of 1. feed coliform group is that the positive rate of all kinds of feed is from high to low: 87.8% of husks, 78.9% of fine material, 76.3% of straw, 73% for mixed feed, 52.1% for hay and negative in silage; the main feed and its raw materials are different from the different beef and cattle breeding fields in the north and the south. The degree of coliform contamination was not comparable. From the seasonal aspect, the positive detection rate of coliform in the feed samples in the North Xinjiang cattle farm was 58.6%, the winter was 10% and the summer pollution was greater than the winter. The total positive rate of coliform bacteria in the summer beef cattle was 44.7% in southern Xinjiang, and the positive detection rate of the semen and straw in the southern Xinjiang cattle was 44.7%. The average positive rate of coliform bacteria of feed coliform in southern Xinjiang was higher than 50%., and the average positive rate of coliform bacteria was 64% in southern Xinjiang in winter. The mixed feed and fine material were the highest, and the two were higher than that of 50%. South Xinjiang beef cattle breeding farm in different seasons. The average positive rates of the positive feed coliform group were 46.3% and 47%, but there was no significant difference. But from the common feed raw material, the former was more polluted, and the hay pollution of the latter was more heavy.2. from 77 strains of Escherichia coli isolated and identified from the feed samples, and the dominant polyvalent serotypes were O5 and O19. The output rate was 11.86%), followed by the polyvalent antigen serum O16 (10.17%), in addition, the polyvalent O antigen serum O14, O15, O18 were more, the detection rate was 6%. and the 205 strains of Escherichia coli isolated from the fecal source identified the polyvalent serotype, the dominant polyvalent serotypes were O5 and O6, the detection rate was 13.82% and 10.57% respectively, and the polyvalent O antigen serotype O4, O13 The detection rates of O14, O17 and O20 were all 5%, and the results of virulence gene detection showed that 48 strains of Escherichia coli were carrying virulence genes, of which the detection rate of virulence gene stx1 was 43.7%, the detection rate of virulence gene Stx2 was 45.8%, and the detection rate of virulence gene EAE was 37.5%. analysis and found that there existed between O anti original polyvalent serotype and Escherichia coli virulence gene. This study provides scientific data for the risk assessment of microbial contamination in beef feed and lays a foundation for the establishment of the standard of microbial contamination limit for beef cattle feed. Set the foundation.
【学位授予单位】：新疆农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S852.61

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