Decline of zoonotic agents in livestock waste and bedding heaps

Abstract

To measure the rates of decline of zoonotic agents introduced into heaps of spent bedding and faecal wastes generated by commercially farmed livestock and managed in a similar way to that of a working farm. Livestock isolates of Salmonella, pathogenic Listeria, Campylobacter and Escherichia coli O157 were laboratory cultured and used to inoculate 5 m3 heaps of cattle, sheep or pig wastes mixed with bedding materials. Decline of each of the infectious agents was monitored with time as was the temperature inside each heap. Temperatures of >50 degrees C were typically achieved at the core of the heaps. Pathogen decline was rapid, typically <3 days for a 1-log reduction in levels. The longest time that zoonotic agents were isolated from the heaps was 93 days. Movement of heaps of livestock bedding waste from animal pens to a secondary store, and storing them under conditions conducive for increased temperature is a simple and cost-effective treatment for rapidly lowering levels of zoonotic agents in solid farm wastes. This study demonstrates a simple and cheap treatment that can be used to help prevent the spread of zoonotic agents through agricultural environments.