Broiler farming practices using new or re-used bedding, inclusive of free-range, have no impact on <i>Campylobacter</i> levels, species diversity, <i>Campylobacter</i> community profiles and <i>Campylobacter</i> bacteriophages

Abstract

<abstract> <p>A multi-stage option to address food-safety can be produced by a clearer understanding of <italic>Campylobacter</italic>'s persistence through the broiler production chain, its environmental niche and its interaction with bacteriophages. This study addressed <italic>Campylobacter</italic> levels, species, genotype, bacteriophage composition/ levels in caeca, litter, soil and carcasses across commercial broiler farming practices to inform on-farm management, including interventions.</p> <p>Broilers were sequentially collected as per company slaughter schedules over two-years from 17 farms, which represented four commercially adopted farming practices, prior to the final bird removal (days 39–53). The practices were conventional full clean-out, conventional litter re-use, free-range–full cleanout and free-range–litter re-use. Caeca, litter and soil collected on-farm, and representative carcases collected at the processing plant, were tested for <italic>Campylobacter</italic> levels, species dominance and <italic>Campylobacter</italic> bacteriophages. General community profiling via denaturing gradient gel electrophoresis of the <italic>flaA</italic> gene was used to establish the population relationships between various farming practices on representative <italic>Campylobacter</italic> isolates. The farming practice choices did not influence the high caeca <italic>Campylobacter</italic> levels (log 7.5 to log 8.5 CFU/g), the carcass levels (log 2.5 to log 3.2 CFU/carcass), the <italic>C. jejuni</italic>/<italic>C. coli</italic> dominance and the on-farm bacteriophage presence/levels. A principal coordinate analysis of the <italic>flaA</italic> distribution for farm and litter practices showed strong separation but no obvious farming practice related grouping of <italic>Campylobacter</italic>. Bacteriophages originated from select farms, were not practice-dependent, and were detected in the environment (litter) only if present in the birds (caeca).</p> <p>This multifaceted study showed no influence of farming practices on on-farm <italic>Campylobacter</italic> dynamics. The significance of this study means that a unified on-farm risk-management could be adopted irrespective of commercial practice choices to collectively address caeca <italic>Campylobacter</italic> levels, as well as the potential to include <italic>Campylobacter</italic> bacteriophage biocontrol. The impact of this study means that there are no constraints in re-using bedding or adopting free-range farming, thus contributing to environmentally sustainable (re-use) and emerging (free-range) broiler farming choices.</p> </abstract>