Studies on survival of pseudorabies virus, Actinobacillus pleuropneumoniae, and Salmonella serovar Choleraesuis in composted swine carcasses

Objective: To monitor survival of pseudorabies virus (PRV), Actinobacillus pleuropneumoniae (App), and Salmonella serovar Choleraesuis (Sc) in composted swine carcasses. Methods: In Experiment One, pigs were infected with PRV, infected 2 days later with App, and euthanized 15 to 16 hours after App infection. Carcasses were then composted for 35 days. In Experiment Two, pigs were infected with Sc and euthanized 3 days later, and carcasses were composted for 10 days. Compost piles were constructed inside buildings with concrete floors. In both experiments, temperature of the composting piles was monitored daily, and samples were obtained from the carcasses for microbiologic evaluation at intervals throughout the composting period. Results: Temperature of the composting piles ranged from 27 to 51 degrees C in Experiment One, and 27 to 62 degrees C in Experiment Two. Composted carcasses degraded rapidly. After 7 days, only bones, teeth, large muscles, and portions of the hide were physically recognizable. Muscle and bone were discolored, and bones were more easily crushed or broken. The hide was less collagenous and tore into several pieces when carcasses were extracted from piles. In Experiment One, tissue samples collected on Composting Days 7 and 14 were culture negative for PRV and App. In Experiment Two, Sc was recovered from samples collected on Composting Days 0, 1, and 3, but not from samples collected on Days 7 or 10. Implications: Under the conditions of these experiments, composting can be used to dispose of swine carcasses containing PRV, App, and Sc.