Lab-scale evaluation of on-farm methods to mitigate gaseous emissions from staged swine carcasses

Animal health emergencies, such as infectious disease outbreaks, threaten livestock industries as depopulation of animals may require on-farm carcass retention until final disposal methods are available. As carcasses decay, they release gases that attract scavengers and insects that may spread the disease. This lab-scale study evaluated on-farm materials and approaches to temporarily manage carcasses and mitigate gas emissions. The tested materials included tarps, soil, corn stover (CS), and lime, and techniques used to manage carcasses focused on reducing oxygen availability, desiccating carcasses, and using chemical additives. Carcass mass, temperatures, headspace gas, and leachate were collected over 91 days. Pairwise comparisons of rates and means were made when treatments were significantly different. Covering or containing carcasses in tarp material reduced air exchange and significantly (p < 0.05) reduced decomposition rates by 40 and 90 %, respectively; CS material desiccated carcasses and significantly (p < 0.05) reduced decomposition rates by 50 % while covering carcasses with soil or lime had no effect on decomposition. Covering carcasses significantly reduced C and N emissions by over 50 %, and wrapping carcasses reduced emissions of C and N by over 80 %. However, no treatment effectively reduced emissions of dimethyl disulfide, a chemical that attracts scavengers. While growers and animal health officials work to reduce decomposition and prevent contamination of carcass material from entering the environment, these efforts could be undermined if gases emitted from carcasses attract scavenger organisms that subsequently gain access to carcasses and spread of diseased tissues. These findings highlight the need for integrated management strategies reduce carcasses decomposition with increased biosecurity.