Co-composting of swine mortalities with swine manure and sawdust

The treatment of livestock fatalities caused by epidemic diseases must be timely. Simultaneously, the contaminated excreta and bedding materials must also be treated on site without removal. The composting of manure with bulking materials is widely used on the farm, and the temperature during the composting reaches over 60 degrees C under appropriate conditions of moisture and oxygen, with a suitable carbon to nitrogen ratio. These characteristics of composting can be applied to the degradation of dead livestock. Hence, this study was conducted to evaluate the degradability of mortalities during composting with bulking material comprised of swine manure and sawdust. The laboratory and field studies were conducted using mimic swine mortalities (MSM) and real swine mortalities, respectively. The sawdust to swine manure ratios of 20:80, 40:60, 70:30, and 100:0 were treatments identified as T-1, T-2, T-3, and T-4. In the laboratory study, high degradation of the mortalities (>85%) occurred in all treatments, except the T-1 treatment. The T-2 treatment obtained high degradation at a desirable level. In the field study, the degradation of the soft tissues of the mortalities in the T-2 and T-1 treatments reached 99.7 and 84.5%, respectively. The final C/N ratio of treatment T-2 (17.5) was higher than treatment T-1 (16.8). The addition of swine manure helped to develop relatively rapid temperature homogeneity between the mortality and the bulking materials, and the sawdust to swine manure ratio of 40:60 proved best for swine carcass degradation.