Assessing and managing the risk posed by Salmonella in pig feed

Anne Marie Burns

    Research output: Types of ThesisDoctoral Thesis


    Salmonella in pigs and derived pork is a significant food safety concern in Ireland. During commercial pig production, it is proposed that a number of risk factors including commercial feed can introduce Salmonella to fattening pig herds and may thereby cause human infections via consumption of contaminated pork. The objective of this work was to carry out an in-depth study on ten high Salmonella sero-prevalence pig farms to firstly identify which production stages were the principal harbours of Salmonella infection and secondly, to assess the occurrence of Salmonella in feed throughout the different production stages on these farms and thereby assess potential risks as well as epidemiological relationships. Isolates were characterized by serotyping, antibiotic resistance profiling, pulsed field gel electrophoresis (PFGE) and multiple locus VNTR analysis (MLVA). Eleven serotypes were recovered, with a monophasic variant of Typhimurium (4,[5],12:i:) accounting for 41.1% of all isolates recovered. Five Salmonella 4,[5],12:i:- isolates were recovered from the commercial feed mills supplying our pig farms. Typing of all isolates resulted in two common distinct MLVA profiles for both mills and farms. The Salmonella 4,[5],12:i:- variant that predominated in the pigs and feed is an emerging strain in Europe and are of increasing food safety concern. The objective of the final study was to determine the survival characteristics of Salmonella 4,[5],12:i:- strains. The thermal inactivation of the five feed strains at 55, 60 and 65°C was investigated using an immersed heating coil apparatus. The ability of the five strains to survive during storage on weaner pig feed premixed with Sodium Butyrate was also assessed over 28 day storage. The key findings in this study is the confirmation of monophasic Salmonella Typhimurium occurrence in new geographical settings and the indication of its possible role in the transmission of Salmonella from contaminated feed ingredients and feed to pigs.
    Original languageEnglish
    Awarding Institution
    • Gardiner, Gillian E., Supervisor
    • Duffy, Geraldine, Supervisor, External person
    • Lawlor, Peadar G., Supervisor, External person
    Publication statusUnpublished - 2015


    • Salmonella


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