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Schmidt: Consider composting animal mortalities

By Staff | Sep 12, 2014

As many of you know, a big part of an extension agent’s job is continuing education. Last week I spent two days at the Carrington Research Extension Center with a number of my colleagues from across the state for our annual fall livestock in-service. As usual we received an abundance of great information to help us help the people we serve. In addition we had the opportunity to collaborate with other agents and specialists as part of NDSU Extension’s statewide livestock program team to develop and evaluate programs and activities to address priority issues across our state. While all of the details of our programming efforts are not in place yet, I can tell you to be on the lookout for some exciting learning opportunities in the areas of livestock immunology and livestock handling coming to a county near you in the next year!

One of the other issues we focused on that I’m excited to share with livestock producers is the option of composting animal mortalities which is one of the approved methods of managing animal mortalities in North Dakota.

Though dragging a dead animal carcass off to the boneyard has been a common historical practice, abandonment is NOT recommended and is likely ILLEGAL in many places. Proper mortality disposal prevents the spread of infectious, contagious and communicable diseases and protects air, water and soil quality.

There are four methods of disposing of livestock mortalities that are considered to be safe and environmentally friendly. These are: rendering, incineration, burial and composting.

During the time I spent working in the livestock industry in South Dakota, I had my first exposure to animal mortality handling methods different than I had experienced during my working experiences here in my home state. In the area of South Dakota where I worked, rendering was a common mortality disposal method.

Here in North Dakota where many areas are not regularly serviced by rendering trucks and managing animal mortalities through burial can pose a groundwater contamination risk if the burial site is not selected and managed properly, composting these mortalities is an easy economical option with lower air and water pollution risk.

During our livestock in-service, my extension colleagues and I were able to take part in a tour of the livestock mortality compost area at the Carrington Research Extension Center. Part of this experience included opening one of the mortality piles that contained the remains of a calf that had been started near mid-July. When the mortality pile was opened I was pleasantly surprised to see that the carcass of the deceased calf had already turned to compost and was ready to be used as a nutrient source on fields.

To help understand how this process works, let’s review the process of composting. Composting is nature’s way of using bacteria and fungi to break down decaying plant or animal material (organic matter) into basic elements which is recycled as a fertilizer to complete the food web.

This process generates high heat – 120-160 degrees Fahrenheit – which aids in the decomposition process in addition to destroying pathogens.

The basic process for composting animal mortalities involves:

1. Site selection – Choose a site that drains well and where runoff will not contaminate surface water or leach into ground water.

2. Base material – Two feet of base material should be placed on compost site. Recommended base materials include straw, old hay, sunflower hulls or sawdust and should have a high carbon:nitrogen (C:N) ratio.

3. Mortality placement – When placing the mortality on top of the base material allow at least a one-foot perimeter between the carcass and the edge of the base.

4. Bulking material – Cover the carcass with 6-8 inches of bulking material consisting of manure, finished compost or spoiled silage.

5. Cover material – Two feet of cover material should be placed on top of the mortality and bulking material. Recommended cover materials include straw, old hay, sunflower hulls or sawdust. Cover material aids in trapping and maintaining heat for the pile as well as keeping predators out. To maintain proper heat levels it is important that the cover material be maintained throughout the composting process.

6. Maintenance – Piles or windrows can be left untouched for 6-8 months or aerated every two months depending on the amount of time the producer wants to put into maintenance.

Animal size and age are major factors in the amount of time necessary for a mortality to compost. Animal mortality composting can be done all year – even in cold northern climates such as ours.

Keep in mind that livestock mortalities due to contagious or infectious diseases such as anthrax, hog cholera or swine erysipelas will need to be handled differently. If the owner of dead livestock suspects any of the above mentioned diseases he/she should immediately contact their local veterinarian or the State Veterinarian and the Board of Animal Health.

For more information on composting animal mortalities, check out NDSU publication NM-1422, “Animal Carcass Disposal Options.” It’s available online at ag.ndsu.edu/lem/resources/animal-mortality-management.

If you are interested in trying composting to manage your livestock mortalities, I would be happy to help you get started. Call the NDSU Extension Pierce County Extension office at 776-6234 ext. 5.

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