Identification of risk factors for Campylobacter contamination levels on broiler carcasses during the slaughter process

• Slaughterhouses can improve their ability to control Campylobacter.
• Five slaughter process characteristics have been identified as risk factors.
• Carcass contamination is associated with Campylobacter caecal colonization level.
• External contamination of incoming birds has been identified as a risk factor.
• The longer transport and holding time, the lower Campylobacter counts on carcasses.

Campylobacter carcass contamination was quantified across the slaughter line during processing of Campylobacter positive batches. These quantitative data were combined together with information describing slaughterhouse and batch related characteristics in order to identify risk factors for Campylobacter contamination levels on broiler carcasses. The results revealed that Campylobacter counts are influenced by the contamination of incoming birds (both the initial external carcass contamination and the colonization level of caeca) and the duration of transport and holding time that can be linked with feed withdrawal period. In addition, technical aspects of the slaughter process such as a dump based unloading system, electrical stunning, lower scalding temperature, incorrect setting of plucking, vent cutter and evisceration machines were identified as risk factors associated with increased Campylobacter counts on processed carcasses. As such the study indicates possible improvements of the slaughter process that can result in better control of Campylobacter numbers under routine processing of Campylobacter positive batches without use of chemical or physical decontamination. Moreover, all investigated factors were existing variations of the routine processing practises and therefore proposed interventions are practically and economically achievable.