In-vessel bioreduction provides an effective storage and pre-treatment method for livestock carcasses prior to final disposal

The EU Animal By-Products Regulations forbid the burial of livestock carcasses on land. Farmers would benefit from the availability of biosecure and economically viable alternatives for storing and disposing of dead animals. We assessed the efficacy of bioreduction vessels as a mechanism of storing and reducing the volume of fallen livestock prior to ultimate disposal. Two experimental scenarios were tested: (1) a single input of 300 kg of dead sheep with no further inputs for 3 months, and (2) a continuous 'on-farm' addition of dead sheep over 12 months (ca. 2-3 t animals vessel^-1). The trials involved half-filling the vessels with water, addition of the dead sheep with subsequent heating (40 °C) and aeration of the liquor. Each trial was repeated three times. Our results showed a complete biodigestion and liquefaction of the animals alongside a significant bioreduction in the volume of the liquid. No pathogens could be detected in either the waste or the gaseous emissions. Calculations showed that bioreduction may offer significant long-term savings for farmers in terms of animal disposal costs. Our findings suggest that bioreduction may offer a practical, biosecure, and cost-effective method of storing fallen livestock prior to disposal via rendering or incineration.