Presence and incidence of food-borne pathogens in Australian chicken litter

Abstract

1. Litter samples were collected at the end of the production cycle from spread litter in a single shed from each of 28 farms distributed across the three Eastern seaboard States of Australia.

2. The geometric mean for Salmonella was 44 Most Probable Number (MPN)/g for the 20 positive samples. Five samples were between 100 and 1000 MPN/g and one at 10⁵ MPN/g, indicating a range of factors are contributing to these varying loads of this organism in litter.

3. The geometric mean for Campylobacter was 30 MPN/g for the 10 positive samples, with 7 of these samples being <100 MPN/g. The low prevalence and incidence of Campylobacter were possibly due to the rapid die-off of this organism.

4. E. coli values were markedly higher than the two key pathogens (geometric mean 2⋅0 × 10⁵ colony forming units (cfu)/g) with overall values being more or less within the same range across all samples in the trial, suggesting a uniform contribution pattern of these organisms in litter.

5. Listeria monocytogenes was absent in all samples and this organism appears not to be an issue in litter.

6. The dominant (70% of the isolates) Salmonella serovar was S. Sofia (a common serovar isolated from chickens in Australia) and was isolated across all regions. Other major serovars were S. Virchow and S. Chester (at 10%) and S. Bovismorbificans and S. Infantis (at 8%) with these serovars demonstrating a spatial distribution across the major regions tested.

7. There is potential to re-use litter in the environment depending on end use and the support of relevant application practices and guidelines.

Acknowledgements

This research was supported by the Australian Rural Industries and Research Corporation. The technical assistance of Kate Russel and Adam Gale is acknowledged. The support of the companies and farms concerned is also acknowledged.