Scientific Abstract
Composting for routine and catastrophic mortality management has become an accepted practice in the United States. Compost provides an environmentally and economically sustainable method to recycle nutrients from the animals into the agricultural system. To date, composting of whole carcasses has been the primary methodology for both routine and catastrophic events. Four issues have been identified with whole animal composting during a foreign animal disease (FAD) event: disease inactivation, length of time for composting, bone management, and carbon quantities.
African Swine Fever (ASF) is a disease of major concern for the swine industry, potentially causing severe economic loss (You, 2021). Research has shown the inactivation of ASFv occurred within 3-7 days using whole carcasses in compost piles through both PCR and live cell culture (Gabbert et al., 2023, Hutchinson, et al. 2023, and Fisher, et al. 2020). The USDA Livestock Mortality Composting Protocol (USDA, 2017) provides guidelines for static windrow composting, a 6-12 weeks process that would significantly impact business continuity during a FAD event. Prior work has shown that particle reduction accelerates tissue degradation during the compost process. Particle reduction has been primarily accomplished by using large horizontal grinders. An alternative would be to use a compost turner after a period of pre-composting.
In this proof-of-concept project, the researchers used a compost turner in windrows with whole sow carcasses to determine when and if turning reduces particle size and soft tissue degradation. Very little carcass soft tissue was found after the turning process, including just 7 days following initial composting. There was no significant difference in soft tissue presence when turned at 7, 14, or 28 days. However, large bones were still present at all times. The turner was compared with a horizontal grinder after 14 days of composting. Soft tissue degradation scores were 5 (no soft tissue or bones present) and 4 (no soft tissue; some bone present) for grinding and turned windrows, respectively. The difference in the scores is a reflection of the large bones present when a compost turner is used, whereas horizontal grinding eliminates bone presence. The amount of carbon material required for composting if carcasses are pre-conditioned and turned vs. round was reduced, but not quantitatively measured. The largest reduction in carbon requirements was the result of no additional carbon being required for capping the windrows. Reducing the particle size significantly reduces the time needed for the compost process. Particle reduction could potentially decrease the loss of production time to 14-21 days, reducing carbon inputs with minimal risk of virus spread.
