Split Marketing as a Risk Factor for Salmonella enterica Infection in Swine

Livestock Behavior Research Unit, Agricultural Research Service, U.S. Department of Agriculture, West Lafayette, Indiana 47907, USA.
Foodborne Pathogens and Disease (Impact Factor: 1.91). 09/2009; 6(7):865-9. DOI: 10.1089/fpd.2009.0309
Source: PubMed


On-farm reduction of Salmonella carriage prevalence in pigs requires the identification of risk factors to direct interventions development. This study was designed to determine if split marketing of finishing pigs constitutes a risk factor for Salmonella infections, by comparing Salmonella prevalence in the first group of pigs selected for harvest ("first pull") versus the prevalence in the last group of pigs selected for harvest ("close out") from multiple commercial finishing lots. Nine paired samplings were conducted consisting in matched groups of pigs from individual barns as the first pull and the close out with a 4-week interval between groups. From each group, fecal and meat samples were collected, on-farm and at harvest, respectively. Fecal samples were selectively enriched, and analyzed for the presence of Salmonella, whereas meat juice samples were analyzed for the presence of antibodies against Salmonella. In 7/9 (77.8%) of the studied barns, an increase in Salmonella prevalence was observed, based on both bacteriologic and serologic analysis. Overall, there was an increase of 9.2% (p < 0.05) in bacteriologic prevalence, and 31.3% (p < 0.05) in serologic prevalence from first pull to close out groups. This study demonstrates that a significant increase in Salmonella prevalence occurs between the first and the last group of pigs harvested from finishing lots, with close out groups of market pigs posing a higher risk for Salmonella contaminations.

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    • "Recently, the use of molecular tests was used to assess the presence of Salmonella in ICLN and the results indicate that the concentration of Salmonella was very low and bacterial cells were mostly unevenly distributed within the tissue (Mann et al., 2014). It should also be pointed out that stress factors associated with transport have been linked to increased pathogen carriage, disease susceptibility, carcass contamination and pathogen shedding (Burkholder et al., 2008; Rostagno et al., 2009). Detection of Salmonella in the cecal content may be due to either active infection or transit through gut, whereas the presence in lymph nodes suggests infection that unlikely occurred between the farm and slaughter. "
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    • "2011) and in experimentally infected and slaughtered swine (Wingstrand et al., 1997; Lundén et al., 2002). Meat juice is also used for the detection of other foodborne pathogens, such as Trichinella, Ostertagia ostertagi, Fasciola haepatica, Taenia saginata , Salmonella, and Porcine reproductive and respiratory system virus (Beck et al., 2005; Abuseir et al., 2007; Charlier et al., 2009; Rostagno et al., 2009; Gó mez-Laguna et al., 2010). "
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    • "It has been shown that when the heaviest pigs are removed first for market, the lighter pigs that remain in the barn present significantly higher levels of Salmonella prevalence in faeces, indicating some potential reactivation of the infection at that time and, therefore, an increased exposure to Salmonella for the non-infected pigs in the box. However, under this scenario, a serological response is detected at the slaughterhouse (Rostagno et al., 2009). In our farms, this practice is common and the time between both groups of pigs usually reaches up to 30 days, which would have allowed for the detection of an immune response if pigs were infected. "
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