An Investigation into the Efficacy of Washing Trucks Following the Transportation of Pigs—ASalmonellaPerspective

Abstract

Washing of trucks before leaving the abattoir is mandatory in the Republic of Ireland; however, little is known about the efficacy of the cleaning methods in use on trucks following the transportation of live pigs in Ireland. A National Salmonella Control Programme is in place in the Republic of Ireland, which requires the categorization of all pigs according to their Salmonella status. Herds in categories 1, 2, and 3 have a serological prevalence of infection with Salmonella serotypes of <or=10%, >10% to <or=50%, and >50% to <or=100%, respectively. Healthy pigs can carry Salmonella serotypes in their intestine, and the stress of transport may induce these carriers to shed the bacterium at a higher rate. Salmonella-contaminated trucks may infect other farms, abattoirs, and other animals if the trucks are not cleaned between trips. The main objective of this study was to determine the efficacy of washing trucks transporting pigs from category 1 and category 3 herds. In total, six category 3 and three category 1 herds were followed to three separate abattoirs. Salmonella organisms in samples collected from farm pens and from trucks preload, postload, and after washing were quantified and compared using serotyping, phage typing, and pulsed-field gel electrophoresis (PFGE). Enterobacteriaceae counts were also evaluated to indicate the level of contamination of the environment with enteric bacteria. Results suggest that although trucks are visually clean after cold-water power hosing, such washing is not effective at reducing levels of Enterobacteriaceae regardless of category. Of the 108 samples taken from trucks transporting category 3 herds, 6% were positive for Salmonella spp. preload, 17% postload, and 18% after washing. In contrast, of the 54 samples taken from trucks transporting the three category 1 herds, 11% were positive for Salmonella spp. preload, 11% postload, and 6% after washing. Salmonella isolates from the trucks postload and after washing were indistinguishable, based on PFGE patterns, from salmonellae isolated on farm, indicating the probable shedding by carrier pigs during transit. These results demonstrate the need for better cleaning of trucks after each load, particularly when transporting pigs from high-risk herds.

Prevalencia de Salmonella spp. en carne porcina, plantas de beneficio y expendios del Tolima

“…en el estabulado de los animales de un rango de 20-100% a intervalo de 0 a 15% mediante la aplicación de protocolos de limpieza e higiene estrictos en cerdos asociados. De la misma manera, Mannion et al, (2008) demostraron la necesidad de una limpieza más exigente de los camiones de transporte para reducir el potencial de contaminación de los cerdos.…”

Scientific Opinion on a Quantitative Microbiological Risk Assessment of Salmonella in slaughter and breeder pigs

“…In addition, age-(and where possible source-) segregated rearing can reduce Salmonella pressure and thereby avoid contamination spread throughout the entire farm, provided efficient biosecurity measures and all-in/all-out management is strictly applied (see below). In close relation to pig movements stands the role of trucks or other vehicles used for pig transportation (Mannion et al, 2008). Only clean, disinfected and dry vehicles should be allowed to enter the farms to load pigs, hence avoiding contamination.…”

“…Despite cleaning and disinfection efforts, residual Salmonella contamination can occur (Mannion et al, 2008). Data published on the proportion of pigs being transported to slaughter and between farms at national level are scarce in the EU.…”

“…The effect of separate transport, lairage and slaughter depending on the farm status (logistic slaughtering) was assessed and suggested (Boes et al, 2001;Swanenburg et al, 2001b). Trucks used for transport can remain contaminated even after being cleaned and, thereby, be a source of Salmonella for incoming pigs (Dorr et al, 2009;Mannion et al, 2008). The skin of the pigs can easily get contaminated on board since physical contact with the floor is favoured through the fighting behaviour the pigs use to express and through the truck movements as well.…”

“…Modelling this lack of compliance may not be straightforward. Hence, it is assumed in this opinion that all EU regulations are complied with.Despite cleaning and disinfection efforts, residual Salmonella contamination can occur (Mannion et al, 2008). Data published on the proportion of pigs being transported to slaughter and between farms at national level are scarce in the EU.…”