Department of Large Animal Sciences, Faculty of Life Sciences, University of Copenhagen, Grønnegårdsvej 8, DK-1870 Frederiksberg C, Denmark.
Prev Vet Med. 2010 Jul 1;95(3-4):231-8. doi: 10.1016/j.prevetmed.2010.04.007. Epub 2010 May 26.
The Danish Salmonella Surveillance-and-Control Programme in finisher pigs includes both herd and carcass surveillance. Herd surveillance consists of serological testing of meat-juice samples and classification of herds into three Salmonella seroprevalence levels. At the abattoirs, carcass swabs from five pigs are collected daily and analysed as a pooled sample to evaluate the Salmonella carcass prevalence. This study aimed to investigate factors associated with Salmonella carcass prevalence in Denmark. A total of 20,196 pooled carcass swabs collected in 23 Danish abattoirs were included in the analysis. A multilevel logistic regression model was used taking into account the two-level data structure (abattoir, carcass pool) and adjusting the parameter estimates to the random variation at the abattoir level. Study results indicated that carcass contamination was mainly influenced by the probability that at least one pig contributing to the pool was seropositive, the log-transformed number of seropositive pigs delivered to the abattoir on the same day and weekday. No other factors were found to be significant (P>0.05). Large reductions in the number of seropositive pigs delivered to slaughter are unlikely to result in large reductions of the Salmonella carcass prevalence, unless the number of seropositive pigs can be kept below approximately 200. On average, individual Salmonella carcass prevalence can be kept below 1% by keeping a Salmonella input to the abattoir below approximately 50 seropositive pigs. Variation between abattoirs suggested that improved hygiene practices in some of the abattoirs would reduce the Salmonella carcass prevalence further.
丹麦育肥猪中的沙门氏菌监测和控制计划包括群体和胴体监测。群体监测包括肉汁样本的血清学检测，并将群体分为三个沙门氏菌血清流行率水平。在屠宰场，每天从五头猪采集胴体拭子并进行混合样本分析，以评估沙门氏菌胴体流行率。本研究旨在调查与丹麦沙门氏菌胴体流行率相关的因素。共纳入了来自丹麦 23 个屠宰场的 20,196 份混合胴体拭子进行分析。采用多水平逻辑回归模型考虑了两级数据结构（屠宰场、胴体池），并根据屠宰场水平的随机变异调整参数估计值。研究结果表明，胴体污染主要受以下因素影响：至少有一头猪对池体呈血清阳性的概率、同一天和同一周送入屠宰场的血清阳性猪的对数转换数量。未发现其他因素有显著影响（P>0.05）。如果不能将送屠宰的血清阳性猪的数量保持在 200 头以下，那么降低送屠宰的血清阳性猪的数量不太可能导致沙门氏菌胴体流行率的大幅降低。平均而言，通过将沙门氏菌输入屠宰场保持在大约 50 头血清阳性猪以下，可以将个体沙门氏菌胴体流行率保持在 1%以下。屠宰场之间的差异表明，在一些屠宰场提高卫生实践将进一步降低沙门氏菌胴体流行率。
