Fate of pathogens in a simulated bioreduction system for livestock carcasses

The EU Animal By-Products Regulations generated the need for novel methods of storage and disposal of dead livestock. Bioreduction prior to rendering or incineration has been proposed as a practical and potentially cost-effective method; however, its biosecurity characteristics need to be elucidated. To address this, Salmonella enterica (serovars Senftenberg and Poona), Enterococcus faecalis, Campylobacter jejuni, Campylobacter coli and a lux-marked strain of Escherichia coli O157 were inoculated into laboratory-scale bioreduction vessels containing sheep carcass constituents. Numbers of all pathogens and the metabolic activity of E. coli O157 decreased significantly within the liquor waste over time, and only E. faecalis remained detectable after 3 months. Only very low numbers of Salmonella spp. and E. faecalis were detected in bioaerosols, and only at initial stages of the trial. These results further indicate that bioreduction represents a suitable method of storing and reducing the volume of livestock carcasses prior to ultimate disposal.

► Bioreduction is a novel on-farm storage option for livestock carcasses.
► Legislation demands that pathogens are contained and do not proliferate during carcass storage.
► We examined the survival of key pathogens in lab-scale bioreduction vessels.
► Pathogen numbers reduced in the resulting liquor waste and bioaerosols.
► The results indicate that bioreduction should be validated for industry use.