A foreign animal disease outbreak or other catastrophic event impacting the swine industry may require the need to depopulate facilities, resulting in mass mortalities. If these mass mortalities are responded to improperly, an economic burden and threat to biosecurity will be created. Existing methods pose a risk to biosecurity if the animals were diseased with a highly pathogenic virus. Removing carcasses from an infected facility poses an immediate threat to biosecurity because of the exposure of the pathogen to the environment via air, water, soil, vegetation, or fomites (i.e., people, vehicles, and carcass handling equipment); therefore, more biosecure methods of mortality management strategies are needed for swine. The goals of this project were to create a novel mobile test facility replicating a typical swine finishing barn, validate the facility performance, and execute tests for in-barn carcass management strategies to characterize carcass response.

A mobile, general-purpose laboratory replicating a typical swine production setting equipped with full instrumentation was designed and constructed for small-scale in-barn experimentation. The laboratory is built in style of a typical swine finishing building but allows more control than a full-scale barn and requires less labor and other monetary inputs. The model facility, built on a flat-bed trailer, has two identical, fully instrumented rooms (L × W × H) of 2.24 × 2.29 × 2.05 m (88.0 × 90.0 × 80.5 in.) with a 0.46 m (18 in.) shallow pit, replicating typical swine finishing rooms. Walls were composed of typical wood-frame construction with interior paneling and metal clad on the exterior. Instrumentation allows the environment and air quality of the rooms, along with other parameters, to be controlled and monitored. The rear portion of the trailer includes an instrumentation room to house necessary computers, controllers, and associated equipment. Commissioning of components and verifying function of equipment were performed, which included quantifying infiltration and performing a
thermal analysis for each room. Analysis showed that the infiltration equation was distinct for each room.

Carcasses were desiccated by subjection to heat at a room air temperature of 43°C (110°F) for 16 days. Three carcasses (average=82 kg, SE=1.27 kg) were elevated over individual leachate collection systems in DRA, thereby removing leachate from the room. Three carcasses in DRB were placed on concrete slats with cumulative leachate collection in the pit below. Environmental data were collected for DR, outdoor, and slat temperatures; CO2, CO, O2, and NH3 gas concentrations; and odor samples. Carcasses were characterized by rectal and shoulder temperature monitoring and daily weighing of carcasses and leachate in DRA. Air exchange rate for this unventilated system was quantified based on wind and thermal driven infiltration. Room environments were compared for thermal performance and air quality. Carcass temperatures were compared, and data suggested there was no significant impact of flooring material on internal carcass temperature. Gompertz and logistic models were fit to leachate production data and carcass mass reduction data. Ammonia generation rates were found to have a peak production rate of 96.5 g AU-1 day-1 (15.8 g animal-1 day-1) in DRA and 120 g AU-1 day-1 (19.7 g animal-1 day-1) in DRB. Over the entirety of the study, generation of NH3 in DRB (360 g) was nearly twice that of DRA (182 g) due to the removal of leachate. Olfactometry panel results concluded no significant difference between odor emission of the DRs and an average dilution to threshold level of 5,217.

Knowledge of environmental impacts on building construction and gas and odor production of carcass management in-barn will help inform future research for in-barn carcass management strategies. Additionally, knowledge of carcass decomposition rates and internal carcass temperature will help gauge when mortalities can be removed from group-housed confinements to continue decomposing using an established carcass management method. This research will assist the swine industry by providing more biosecure in-barn alternatives to carcass management than existing methods in the event of a disease outbreak or other mass mortality event. Further, this project has advanced the existing knowledge of in-barn strategies for swine and, if adopted, will aid in reducing potential disease spread due to poor carcass management.
For more information, please contact Dr. Brett Ramirez in the Department of Agricultural and Biosystems Engineering at Iowa State University; email: bramirez@iastate.edu

Key Findings
• A mobile, general-purpose laboratory replicating a typical swine production setting equipped with full instrumentation was designed and constructed for small-scale in-barn experimentation.
• Many useful features such as cameras, environmental monitoring, and remote ventilation control make the laboratory a preferred space to carry out a variety of studies on a small-scale.
• Release of NH3 by carcasses and leachate during in-barn swine carcass desiccation was found to be approximately twice that of desiccation in which leachate was removed.
• Gompertz and logistic models were found to fit data well for carcass mass reduction and leachate production, with a Gompertz model having a slightly better fit.
• No significant differences in odor dilution thresholds were observed by an olfactometry panel for the study.
• The parameters assessed aid in preliminary characterization of carcasses during in-barn carcass management for swine. Additional data collection may lead to creation of an accurate model for swine carcass decomposition under controlled conditions based on initial carcass mass and varying environmental factors.