21: Mortality Composting

Why can’t you dispose of carcasses on the “back 40”

It is illegal, and it is a source of contamination

Five methods of lawful carcass disposal

1. Rendering

2. Incineration

3. Landfills

4. Burial

5. Composting

Requirements for carcass burial in Oklahoma

• Not less than 1 ft above flood plains

• Not within 2ft of the water table or bedrock

• Not within 300 ft of water sources, houses, public areas, or property lines

• Must be covered with minimum 2.5 ft of soil

Three ingredients needed for mortality composting

Nitrogen, carbon, and water

What ingredient for composting does a carcass provide

Lots of Nitrogen!

Common sources of carbon for composting piles

• Sawdust

• Straw

• Old hay

• Corn stalks

• Peanut/rice hulls

• Finished compost

• Manure

• Etc.

Four conditions needed for mortality composting

• Proper C:N ratio

• Proper moisture content

• Available oxygen

• Adequate pore size or air space in the pile

What is the proper C:N ratio for mortality composting

C:N of 30:1

What type of decomposition do we want when doing mortality composting

Aerobic decomposition

T/F: you can use finished compost as a sole carbon source for mortality composting

F, often you need to mix it with something else

If you use poultry litter as your carbon source for composting, why does it need to be covered

It is high in phosphorous, and you need to avoid having runoff

Proper moisture amount for composting

50%

What happens if your compost has too little water

The decomposition is slow

What happens if your compost has too much water

It will displace the oxygen and you will end up with anaerobic decomposition

What happens if your compost switches to anaerobic decomposition

• Slower

• Cooler

• Smelly

How can you minimize runoff from your compost pile

Make sure that rain and storm water are directed away from the pile

How hot should your compost pile get

• >130F to kill plants and most pathogens

• <160F to keep the bacteria alive

Carbon source that alone may have too large pore sizes

Long stem hay or straw

Considerations when selecting your compost site

• Keep it away from water sources or buildings

• Put it where your heavy equipment won’t get stuck

• You may need a fence to keep critters out

How is composting different for large animal operations and CAFOs

They need plans, and some states require permits

What is the smallest diameter you can use for a free-standing compost pile

6-7 ft across, smaller than that and it won’t retain enough heat

How thick should the base of your compost pile be

At least 18 inches after being compressed

Where should a carcass be placed in a pile

In the middle of the base, minimum 12 inches from any walls or sides

If you are adding multiple carcasses to your compost pile, how should they be placed

• Back to back

• Feet towards the edge

• 8-10 inches apart for adults, 6 inches for kids/ewes

Why should you lance the rumen before composting

Speeds up microbial access and prevent anaerobic gas development within the carcass

If you are putting a second layer of carcasses on your compost pile, how much carbon source should be between your layers of carcass

6-12 inches

How thick should your cover layer be on your compost pile

18 inches of carbon source material

Function of top cover layer on your compost pile

• Retains heat

• Traps gases

• Absorbs moisture

• Discourages insects and scavengers

Why should you check on your compost pile

To make sure it doesn’t shrink too much and to ensure that nothing is scavenging your carcasses

Ways to assess the temperature of your compost pile

Long stem thermometer or bar of metal stuck into the core of the pile

When should a compost pile be turned

As the temperature starts dropping closer to ambient temperature, often close to 75 days

Why should you aerate your compost pile halfway through

Aerating the material speeds up the process

What is broken down by the first heat cycle of mortality composting

Flesh and some bone

What is broken down by the second heat cycle of mortality composting

Most of the rest of the bone

How long does it take for the second heat cycle of mortality composting to stabilizie

75 days

What color is good, finished compost

A very dark brown, almost black

If you are going to compost an animal that died from an infectious disease, where should you compost it

As close to the infected site as possible to prevent disease spread

T/F: you can compost animals that have died from prion diseases

More research is needed, but right now the state vet won’t let you :)

AVMA acceptable methods of euthanasia

• IV barbiturates

• Gunshot

• Penetrating captive bolt

• Non-penetrating captive bolt + adjunct method

AVMA adjunctive methods for euthanasia

• Exsanguination

• IV KCl or mag sulfate into an already unconscious animal

• Second gunshot

• Pithing

Best site for captive bolt euthanasia

Poll

Secondary site for captive bolt euthanasia

By the ear or on the forehead

T/F: you can compost animals euthanized via barbiturates

True, if your pile is managed properly, but there are some concerns with residues and secondary toxicosis

How much of your compost pile can be built with finished compost material

50%

T/F: you can use mortality composting as fertilizer for food crops

False