Composting as a means of managing large numbers of livestock mortalities
Summary
Composting has the potential to resolve some of the logistical, practical and environmental problems associated with other available options for managing animal mortalities (e.g. burning or burial). If done properly, composting provides immediate carcase containment and creates temperatures in excess of 55 degrees C, which are sufficient to kill many types of pathogens and disease causing organisms in the carcases and contaminated manure. Since composting is done above the ground, it also poses fewer threats to shallow groundwater than burial.
Consequently, industry, environmental and biosecurity agencies have expressed their interest in composting as an option for managing livestock mortalities arising from intensive agricultural industries, exotic diseases or natural disasters, such as drought and bushfires. However, animal mortality composting has not been trialled in Australia, and no published standard operating procedures exist. This is seen as a major impediment to the use of on-farm composting in an emergency animal disease outbreak. Therefore a need exists to evaluate the risks and benefits of composting as an option for managing large numbers of animal mortalities under Australian conditions.
To address these issues, a trial was established at EMAI in March 2007 with the objectives of:
- determining whether composting is a viable option for managing livestock mortalities;
- evaluating the potential risks associated with composting;
- developing protocols and standard operating procedures for composting animal mortalities; and
- building stakeholder confidence in the use of composting as an option for managing large numbers of livestock mortalities.
This is a collaborative project involving numerous Divisions, Units and sections of the DPI. The role of CROA in the project is to undertake monitoring and evaluation to compare the effectiveness of different options (surface disposal, static pile composting and above-ground burial) for managing livestock mortalities.
The project commenced in March with the construction of the windrows and burial of 35 cattle carcasses. Temperature monitoring has revealed temperatures of the carcases subjected to composting are consistently between 50-60oC, suggesting conditions are adequate to pasteurise the carcasses and the material immediately adjacent to them. In contrast, temperatures surrounding the carcasses subjected to above ground burial were only 20-25oC.
Faecal coliforms and E.coli have been used as indicators for evaluating the survival of disease causing organisms in each of the management options. After 4 weeks, none of the indicators survived in the static pile composting treatments, although viable cultures were obtained from the surface disposal and above ground burial treatments. These results are very encouraging and demonstrate composting is a viable option for managing animal mortalities and reducing biosecurity risks associated with them. Monitoring and evaluation will conclude in September with the 5th and final sampling period.
Duration
2006-2008
Funding body
Commonwealth Department of Agriculture, Fisheries and Forestry (DAFF)
Collaborating organisations
NSW Department of Primary Industries
Project Leader
Dr Chris Dorahy
Elizabeth Macarthur Agricultural Institute, Menangle