Bacterial survival studies to assess the efficacy of static pile composting and above ground burial for disposal of bovine carcases

Abstract

To assess the survival of bacteria during two alternative means of cattle carcase disposal in windrows: static pile composting (SPC) and above ground burial in soil (AGB), under temperate climate conditions on agricultural land, compared to surface disposal as the control method. Bacteriological reference materials (pooled bovine faeces in permeable nylon bags and lyophilized cultures of Escherichia coli in glass ampoules) were positioned above and below each of 33 beef cattle carcases (250-300 kg). Temperatures at these sites were monitored with data loggers, while temperature and CO(2) probes were applied repeatedly at varying depths along the windrows. Aliquots of each reference material were cultured from three randomly selected animals from the SPC and AGB group and from all three control animals on five occasions (at 28, 56, 84, 126 and 182 days). SPC was highly efficacious in the destruction of coliforms in faeces and E. coli in ampoules within 28 days, while AGB was not significantly better than controls until 84 days, and bacteria in reference materials above the AGB carcases were still viable after 182 days. Temperature probes and loggers showed SPC provided sustained temperatures of 55-70°C, while AGB did not reach temperatures of 30°C, and the temperature differences correlated with bacteriological findings. In relation to emergency disease management, SPC can be successfully applied to eliminate pathogenic bacteria in cattle carcases, but AGB is unsuitable for carcase disposal. In emergency, animal disease outbreaks in temperate climates requiring large-scale ruminant carcase disposal, SPC can be successfully applied for the destruction of micro-organisms.