title: Dynamics of Salmonella Shedding and Welfare of Hens in Free-Range Egg Production Systems.
abstract: The current study investigated the effect of environmental stressors (i.e., weather changes) onSalmonellashedding in free-range production systems and the correlations with behavioral and physiological measures (i.e., fecal glucocorticoid metabolites). This involved longitudinal and point-in-time surveys ofSalmonellashedding and environmental contamination on four commercial free-range layer farms. The shedding ofSalmonellawas variable across free-range farms and in different seasons. There was no significant effect of season on theSalmonellaprevalence during this investigation. In this study, the combinedSalmonellamost probable number (MPN) counts in environmental (including feces, egg belt, dust, nest box, and ramp) samples were highest in samples collected during the summer season (4th sampling, performed in February). The predominant serovars isolated during this study wereSalmonella entericaserovar Mbandaka andSalmonella entericaserovar Typhimurium phage types 135 and 135a. These two phage types were involved in several egg product-relatedSalmonellaoutbreaks in humans. Multilocus variable-number tandem-repeat analysis (MLVA) results indicated that MLVA types detected from human food poisoning cases exhibited MLVA patterns similar to the strains isolated during this study. AllSalmonellaisolates (n =209) were tested for 15 different genes involved in adhesion, invasion, and survival ofSalmonellaspp. We also observed variations forsopA,ironA, andmisLThere were no positive correlations between fecal corticosterone metabolite (FCM) andSalmonellaprevalence and/or shedding in feces. Also, there were no positive correlations betweenSalmonellaprevalence andSalmonellacount (log MPN) and any of the other welfare parameters.IMPORTANCEIn this study, the welfare of laying hens andSalmonellashedding were compared over a prolonged period of time in field conditions. This study investigated the long-term shedding ofSalmonellaserovars in a free-range egg production system. Given that there is increasing demand for free-range eggs, it is essential to understand the risks associated with such a production system.
authors.affiliation: School of Animal and Veterinary Science, University of Adelaide, Roseworthy, South Australia, Australia.
authors.forename: Vaibhav C
authors.initials: VC
authors.lastname: Gole
authors.affiliation: Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Woodhouse
authors.affiliation: School of Animal and Veterinary Science, University of Adelaide, Roseworthy, South Australia, Australia.
authors.forename: Charles
authors.initials: C
authors.lastname: Caraguel
authors.affiliation: School of Animal and Veterinary Science, University of Adelaide, Roseworthy, South Australia, Australia.
authors.forename: Talia
authors.initials: T
authors.lastname: Moyle
authors.affiliation: Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Jean-Loup
authors.initials: JL
authors.lastname: Rault
authors.affiliation: Biosecurity SA, Primary Industries and Regions SA, Adelaide, South Australia, Australia.
authors.forename: Margaret
authors.initials: M
authors.lastname: Sexton
authors.affiliation: School of Animal and Veterinary Science, University of Adelaide, Roseworthy, South Australia, Australia kapil.chousalkar@adelaide.edu.au.
authors.forename: Kapil
authors.initials: K
authors.lastname: Chousalkar
mesh_terms: D000827:Animal Welfare; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics; D057138:Bacterial Shedding; D001434:Bacteriophage Typing; D002645:Chickens / Q000382:microbiology*; D003430:Cross-Sectional Studies; D004269:DNA, Bacterial / Q000235:genetics; D004391:Dust; D004531:Eggs / Q000382:microbiology*; D004777:Environment; D005243:Feces / Q000382:microbiology; D005260:Female; D005517:Foodborne Diseases / Q000382:microbiology; D014644:Genetic Variation; D005938:Glucocorticoids / Q000378:metabolism; D008137:Longitudinal Studies; D018598:Minisatellite Repeats; D011201:Poultry Diseases / Q000453:epidemiology; D015995:Prevalence; D012475:Salmonella / Q000235:genetics* / Q000302:isolation & purification* / Q000472:pathogenicity; D012481:Salmonella Infections, Animal / Q000453:epidemiology; D019779:Salmonella enterica / Q000235:genetics / Q000302:isolation & purification; D012486:Salmonella typhimurium / Q000235:genetics / Q000302:isolation & purification; D012621:Seasons; D065288:Serogroup; D014774:Virulence / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004391:Dust; D005938:Glucocorticoids
keywords: Salmonella; eggs; free range; hens; welfare