Abandoning animal carcasses and allowing scavengers to dispose of them is risky.
Though dragging off a carcass to the boneyard has been a historical practice, abandonment is NOT recommended and is likely ILLEGAL in most states. Examples include: carcasses abandoned on the surface, in open pits, ditches, water features and sinkholes or in wells. Abandonment promotes extreme biological and disease hazard, threats to water quality, odors, flies, scavengers, rodents and visual pollution.
The need to dispose of livestock or poultry carcasses is an inevitable part of farming and ranching. What is this process and is it environmentally sound?
Composting is a natural process in which microorganisms convert organic matter into a stabilized product termed compost, which can then be used as a beneficial soil amendment. In the case of livestock mortality composting, the carcass can be placed in a compost bin. At this location, we have used net wire supported by t-posts as our compost bin. The carcass is then covered with a supplemental carbon source. In this case, we have used wood shavings mixed with manure. The carcass is then allowed to decompose through natural microbial activity which breaks down both soft tissue and bones. This process usually takes several months to form a stabilized product.
Composting livestock and poultry carcasses is a cost effective way to manage mortalities on a farm or ranch.
The cost of composting livestock depends largely on the cost of your local carbon source. Sometimes wood chips or shavings can be obtained locally for free from tree removing companies or from local county fair barns and arenas. If building a compost bin, a producer can spend around $50 per bin constructing when using tee-posts and net wire construction. Keep in mind that the carbon source and the bin can be reused for future mortalities.
Composting livestock and poultry carcasses is becoming a more common way to manage mortalities. There are several reasons for this.
Composting is relatively inexpensive when low cost carbon materials are utilized. The high temperatures generated during composting create a very biosecure process which eliminates pathogens and reduces disease transmission when properly managed. Composting is also an environmentally sound method for carcass disposal as it reduces odors as well as carcass leachate by surrounding the carcass with a carbon filter. The composting process creates a beneficial by-product rich in nutrients which can be land-applied as a fertilizer. Composting promotes a positive public perception by adequately disposing of animal carcasses in a sustainable manner without negatively affecting the environment.
Research studies have been done to correlate the temperature of a compost pile containing livestock or poultry carcasses and the amount of pathogen kill achieved at those temperatures. How do you take the temperature of a compost pile? And how does that temperature correlate to pathogen reduction?
Maintaining a temperature of 131 deg F for at least 4 hours assures us that we have reached an appropriate temperature for pathogen reduction. However, to destroy most pathogen and viruses, compost pile should sustain temperature 131 °F or greater for at least 3 consecutive days. The heat is the result of microbial metabolic activity within the compost pile as they are consuming the carcass.
Most bones break down when composting animal carcasses, but a few large bones will usually remain.
With proper composting, the bones will break down over time. This may take several months for larger livestock bones and as little as 60 days for smaller carcasses such as poultry. If large bones remain in the compost pile, they can be added to additional compost piles until completely degraded.
There are many options available for disposing of livestock and poultry carcasses. Rendering is an option in areas where the service is offered, but has some limitations on the type of animals they will pick up.
Compost containing animal carcasses should probably be utilized on crops that are not meant for human consumption for a couple of different reasons.
Disposal of the end product with regard to roadkill compost…we use it on the roadsides and plant vegetation on the roadsides.
With [farm] mortality compost, we want to be careful about where we are putting cows and chickens because we are using it back on the farm. So we may want to remove the large bones [and reuse them as part of the base for the next mortality compost pile]. We do not want to puncture any tires. But the bones do get pitted and will start breaking apart after a couple of cycles of the composting process. We do not want to use this on food crops. We may prefer to use this on field crops where the soil is tilled. We can apply the compost and then till it in. Definitely use it on crops that are harvested above the ground…corn and things like that. Do not use [mortality compost] on root vegetable or on things where we risk contamination if there is a problem.
Mortality compost can also be used in forested areas.
Improperly disposed livestock or poultry carcasses represent a threat to water and air quality.
Proper management of on-farm animal mortalities is vital to every farming operation. Improper disposal of dead animal carcasses can negatively impact surface water and groundwater from carcass leachate. If the animal died of an infectious disease, pathogenic bacteria and viruses may be present within the carcass. These pathogens can be spread by insects, rodents, predators, and subsurface or above ground water movement, as well as through direct contact with other livestock or poultry leading to increased disease transmission risks. Furthermore, many states have rules regulating the proper disposal of livestock and poultry mortalities. Therefore, the purpose of proper mortality disposal is to prevent the spread of infectious, contagious and communicable diseases and to protect air, water and soil quality. Note that regulated AFOs must abide by their animal mortality disposal plan outlined in their nutrient management plan.
Reviewers: Shafiqur Rahman, North Dakota State University and Jean Bonhotal, Cornell University
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