Volkova Victoriya V, Bailey R Hartford, Wills Robert W
Epidemiology Group, Centre for Infectious Disease, School of Biological Sciences, University of Edinburgh, Ashworth Laboratories, Edinburgh, United Kingdom.
PLoS One. 2009 Jul 28;4(7):e6403. doi: 10.1371/journal.pone.0006403.
Contamination of litter in a broiler grow-out house with Salmonella prior to placement of a new flock has been shown to be a precursor of the flock's Salmonella contamination further down the production continuum. In the southern USA, broiler grow-out houses are primarily built on dirt pad foundations that are placed directly on top of the native soil surface. Broiler litter is placed directly on the dirt pad. Multiple grow-out flocks are reared on a single litter batch, and the litter is kept in the houses during downtime between flocks. The effects of environmental determinants on conditions in broiler litter, hence Salmonella ecology within it, has received limited attention. In a field study that included broiler farms in the states of Alabama, Mississippi and Texas we assessed Salmonella in broiler litter at the end of downtime between flocks, i.e. at the time of placement of a new flock for rearing. Here we utilized these results and the U.S. General Soil Map (STATSGO) data to test if properties of soil at farm location impacted the probability of Salmonella detection in the litter. The significance of soil properties as risk factors was tested in multilevel regression models after accounting for possible confounding differences among the farms, the participating broiler complexes and companies, and the farms' geographical positioning. Significant associations were observed between infiltration and drainage capabilities of soil at farm location and probability of Salmonella detection in the litter.
在新一批肉鸡群入舍前，肉鸡育成舍内的垫料被沙门氏菌污染已被证明是该鸡群在后续生产过程中被沙门氏菌污染的先兆。在美国南部，肉鸡育成舍主要建在直接位于原生土壤表面之上的泥土地基上。肉鸡垫料直接铺在泥土地面上。多批育成鸡群在同一批垫料上饲养，并且在鸡群之间的空舍期垫料保留在鸡舍内。环境决定因素对肉鸡垫料状况以及其中沙门氏菌生态的影响受到的关注有限。在一项涵盖阿拉巴马州、密西西比州和得克萨斯州肉鸡养殖场的实地研究中，我们评估了鸡群之间空舍期结束时，即新一批鸡群入舍饲养时肉鸡垫料中的沙门氏菌情况。在此，我们利用这些结果以及美国通用土壤图（STATSGO）数据来检验养殖场所在地土壤的特性是否会影响垫料中检测到沙门氏菌的概率。在考虑了养殖场之间、参与研究的肉鸡养殖联合体和公司之间可能存在的混杂差异以及养殖场的地理位置之后，在多水平回归模型中检验了土壤特性作为风险因素的显著性。研究发现养殖场所在地土壤的渗透和排水能力与垫料中检测到沙门氏菌的概率之间存在显著关联。
