Following 2008 FDA requirements to exclude specified risk material from rendering, many rendering services have stopped collecting ruminant mortalities, or at least have placed restrictions on rendering cattle over 30 months of age. Reduced access to rendering has many cattlemen looking for other options for mortality disposal. Burial, landfilling, incineration and composting are options to consider. On-farm composting has many benefits that make it the best choice for many farms.
Composting of catastrophic cattle losses, large numbers of animals at one time, has special requirements and methods. This kind of mass event composting is covered in a series of information pieces from Iowa State University (ISU) Ag and Biosystems Engineering, www.abe.iastate.edu/cattlecomposting/training-info. In Iowa, catastrophic mortality must also be reported to the Iowa Department of Natural Resources. Guidelines for disposal and reporting may differ by state.
Composting of routine cattle losses, one at a time, is a relatively simple process. All that is required is a suitable site, some bulking agent—sometimes called co-compost material, and some minimal labor using farm equipment.
The process involves building a compost pile with the carcass surrounded by the bulking agent. Twenty-four inches of bulking agent below and over the carcass helps to provide carbon for the composting process as well as absorbing any liquid released and controlling odors, flies and scavengers. Typical bulking agents include ground cornstalks, bedding/manure mix, coarse sawdust and wood chips. The material should be porous to allow air to pass through, high in carbon and relatively dry.
Monitoring the internal temperature of the pile with a compost thermometer gives you an indication of composting progress. A temperature range of 130-160 degrees F indicates good compost activity. Maintaining adequate cover over the pile controls potential problems. Plan on six to 12 months of composting time for large carcasses. The resulting compost can be land applied with consideration to avoid runoff to a water of the state. All that should remain of the carcasses is clean, larger bones. — ISU Extension
