Risk Factors at Slaughter Associated with Presence of Salmonella on Hog Carcasses in Canada

Abstract

Despite application of HACCP systems at slaughter and during processing, Salmonella contamination is still a significant biological hazard associated with pork products. A better understanding of slaughterhouse risk factors and contamination sources are therefore critical to improve control of this bacterium at slaughter level. The overall objective of this study was to identify the risk factors, at slaughter, associated with the presence of Salmonella in hog carcasses. We were also interested in the genetic characterization of the strains in order to assess the origin of contamination. A questionnaire on various potential risk factors was developed, Over 7400 hogs were tested. These hogs originated from 312 randomly selected production lots. The lots came from 8 different provinces and were tested at time of slaughter in 10 different abattoirs. The tests included serology and bacteriology cultures from mesenteric lymph nodes (MLN) and carcasses. Furthermore, pulsed field gel electrophoresis (PFGE) was conducted to establish genetic profiles of selected isolates from carcasses and MLN to compare their profiles to those recovered from the slaughter environment. Multivariate regression analysis indicated that the cleanliness of the hogs and the status of the scald water were significant factors associated with the final bacteriological status of the carcasses. PFGE analysis showed that most isolates from carcasses were similar to those from animals (MLN) and/or pre-evisceration environment.

Prevalence and serovars of Salmonella enterica on pig carcasses, slaughtered pigs and the environment of four Spanish slaughterhouses

“…This fact has been previously described by other authors and has been associated with scalding water of inadequate temperature (Hald et al, 2003;Swanenburg, Urlings, Snijders, et al, 2001). As previously proposed (Giovannacci et al, 2001;Letellier et al, 2009), the temperature of the scalding water seems to be of crucial importance, and Salmonella was not identified in the scalding tank in slaughterhouse D where the water was always around 62°C.…”

Abattoir based survey of Salmonella in finishing pigs in the United Kingdom 2006–2007

“…Salmonella positive meat juice is likely to come from a pig that has been infected at the farm rather than at the abattoir. Therefore more information such as status and size of farm of origin or other farm practices would be necessary to confirm the association between the carcass weight and the positive meat juice or to clarify whether certain abattoirs received pigs from higher Salmonella prevalence farms -which was a risk observed by Letellier et al (2009).…”

“…Nevertheless, although results from different studies varied, all suggested some level of variation between hygiene standards, which may have an effect on the carcass' Salmonella status. Furthermore, studies have found it possible to lower carcass contamination with good slaughter practices, suggesting that a control programme at abattoir level may be promising (Letellier et al, 2009;Mannion et al, 2012).…”

“…However, the risk of carcass contamination is likely to be associated with a number of factors including line speed, number of pigs slaughtered prior to the sampled one, time of day, slaughterhouse hourly throughput and operator competence (Letellier et al, 2009;Arguello et al, 2013). A number of these factors are likely to be correlated at the abattoir level.…”

Cross-contamination and recontamination by Salmonella in foods: A review

“…Continuous environmental infection sources may maintain Salmonella in slaughterhouses indicating inefficient or poor hygiene practices (Botteldoorn et al, 2003). In regard to risk factors at slaughter associated with the presence of Salmonella on hog carcasses, Letellier et al (2009) underlined the importance of the preslaughter and pre-evisceration environment on the final contamination status of carcasses. They observed that cleanliness of the hogs and status of scald water were significant factors associated with Salmonella status of the carcasses at the end of the slaughtering process.…”