title: The impact of biosecurity and partial depopulation on Campylobacter prevalence in Irish broiler flocks with differing levels of hygiene and economic performance.
abstract: BACKGROUND
  Campylobacter jejuni is the leading bacterial food-borne pathogen within the European Union (EU), and poultry meat is the primary route for transmission to humans.
  
  
  METHODS
  This study examined the impact of partial depopulation (thinning), season, and farm performance (economic, hygiene, and biosecurity) on Campylobacter prevalence in Irish broilers over a 13-month period. Ten caecal samples were taken per flock, for a total of 211 flocks from 23 farms during the duration of the study. Campylobacter was isolated and enumerated according to modified published ISO methods for veterinary samples. Biosecurity was evaluated through a questionnaire based on risk factors for Campylobacter identified in previous studies. Hygiene compliance was assessed from audit records taken over the course of 1 year. All information relating to biosecurity and hygiene was obtained directly from the processing company. This was done to ensure farmers were unaware they were being monitored for Campylobacter prevalence and prevent changes to their behaviour.
  
  
  CONCLUSIONS
  Farms with high performance were found to have significantly lower Campylobacter prevalence at first depopulation compared with low-performance farms across all seasons (P≤0.01). Peak Campylobacter levels were observed during the summer season at first thin in both the high- and low-performance groups. Campylobacter prevalence was found to increase to ≥85% in both high- and low-performance farms across all seasons at final depopulation, suggesting that Campylobacter was introduced during the first depopulation. On low-performance farms, four biosecurity interventions were found to significantly reduce the odds of a flock being Campylobacter positive (physical step-over barrier OR=0.17, house-specific footwear OR=0.13, absence of water body within 0.5 km OR=0.13, two or more broiler houses on a farm OR=0.16), compared with farms without these interventions. For high-performance farms, no single biosecurity intervention was identified as significant as this group had full compliance with multiple factors. High-performance farms had significantly better feed conversion ratios compared with low-performance farms (1.61 v 1.67 (P≤0.01)). No differences in flock mortality rates were observed (P≥0.05). This highlights the impact of season, biosecurity, partial depopulation, and farm performance on Campylobacter prevalence in Irish broilers.
authors.affiliation: UCD School of Veterinary Medicine, University College Dublin, Belfield, Dublin, Ireland; shaunandrewsmith@gmail.com.
authors.forename: Shaun
authors.initials: S
authors.lastname: Smith
authors.affiliation: UCD School of Veterinary Medicine, University College Dublin, Belfield, Dublin, Ireland.
authors.forename: Locksley L McV
authors.initials: LL
authors.lastname: Messam
authors.affiliation: UCD School of Veterinary Medicine, University College Dublin, Belfield, Dublin, Ireland.
authors.forename: Joseph
authors.initials: J
authors.lastname: Meade
authors.affiliation: UCD School of Veterinary Medicine, University College Dublin, Belfield, Dublin, Ireland.
authors.forename: James
authors.initials: J
authors.lastname: Gibbons
authors.affiliation: UCD School of Veterinary Medicine, University College Dublin, Belfield, Dublin, Ireland.
authors.forename: Kevina
authors.initials: K
authors.lastname: McGill
authors.affiliation: Teagasc Ashtown Food Research Centre, Ashtown, Dublin, Ireland.
authors.forename: Declan
authors.initials: D
authors.lastname: Bolton
authors.affiliation: UCD School of Veterinary Medicine, University College Dublin, Belfield, Dublin, Ireland.
authors.forename: Paul
authors.initials: P
authors.lastname: Whyte
keywords: Campylobacter; FCR; Ireland; food safety; poultry; season; thinning