by
Susan Schoenian
Date of last revision:
10-Jan-2007 12:22
Sheep and lambs occasionally die and their carcasses can be a hazard to the
environment and other animals, so they require special handling. Dead animals
should be taken care of promptly.To minimize soil or water contamination and
the risk of spreading disease, guidelines for proper carcass disposal must be
followed. Laws pertaining to livestock deaths are different in each state. It
is important to follow the laws in your province, state, and local region.
|
Composting
has been shown to be an economically and environementally sound method
of animal mortality disposal.
|
 |
|
Simply
covering mortalities in manure |
Depending upon your location, disposal options may include incinerating, landfills, burial, rendering, and composting.
Incinerating
Incineration of dead animals is feasible, but it may not be economical. It is
energy intensive and has the potential for polluting the environment if the
incinerator is not operated and maintained properly. The ashes from properly
incinerated dead animals are harmless and do not attract rats, mice, or insects.
Sanitary
Landfills
In some areas, dead animals can be placed in sanitary landfills. Before taking
dead animals to a landfill, producers must check to see if the landfill will
accept dead animals. Even if a landfill is permitted to take dead animals, it
may not be the policy of the landfill operator to accept dead animals.
On-Site
Burial
Burial is the least-preferred method of disposal, due to the potential for water
pollution. However, it may be the only practical option for some producers.Burial
involves digging a grave or pit, filling it with the dead animal, and covering
it with soil. In time, the dead animals will decay. In cold climates, burial
is difficult when the ground is frozen. Areas that have permeable soils, fractured
bedrock, and a seasonable water table must be avoided. The burial site must
be located away (at least 300 feet) from water sources and structures and neighbors.
It needs to be protected from scavengers. Not all counties and states allow
burial of dead animals.
Rendering
Rendering usually recycles the nutrients contained in dead animals as an ingredient
in animal food, especially for pets. However, lack of rendering plants and animal
disease concerns make it difficult to use this option. In 1989, the rendering
industry in the U.S. and Canada began excluding sheep (1 year or older) from
entering the rendering system. This action resulted from the inference made
by British scientists that rendered sheep raw material included in the production
of meat and bone meal was likely an associative link in the transmission of
BSE ("mad cow" disease) in the U.K.
Composting
Composting is rapidly becoming the preferred method of dead animal disposal.
Composting is an aerobic biodegradation process used to decompose organic material.
It transforms a waste product (manure and dead animals) into a useful soil amendment.
Most compost is spread on land. Compost works well because it releases nutrients
slowly during the warm, moist soild conditions that encourage plant growth.
The compost N, P, and K should be considered part of the nutrient management
plan for the field. The compost generated from the decomposition of animal carcasses
should not be given or sold as compost for use off-farm.
1These
figures were taken from various sources.
|
||||||||||||||||||||||||||||||
To make composting work, you need to create and maintain the ideal environment for the microorganisms to function in your pile. There are four essential elements for successful composting: 1) carbon and nitrogen; 2) oxygen; 3) moisture; and 4) temperature. The carbon:nitrogen ratio (C:N) is very important to the composting process. To facilitate the composting process, you will need to add a substrate that is high in carbon to balance the high levels of nitrogen contained in the mortalities. Too low a C:N ratio may cause odors. Too high a C:N ratio may limit microbial activity, resulting in lowered temperatures and slowed decomposition. A C:N ratio ranging from 25:1 to 35:1 is ideal. Clean sawdust has proven to the best substrate for composting animal mortalities. However, other materials with high carbon content can be used, such as straw, corn stalks, corn silage, wood chips, straw-manure mixture, or old feedstuffs.
Oxygen must be present in the pile to support necessary microbial activity. An adequate moisture level is also needed to ensure proper microbial activity in the compost pile. The ideal moisture content is 45 percent, but levels from 40 to 60 are acceptable. Low moisture levels can reduce microbial activity while high moisture levels inhibit the flow of oxygen and can lead to odors. Heat is the result of the composting process and is necessary for composting to work. The more heat there is, the more heat is produced, and the faster the composting process. For proper composting, the temperature must reach at least 131° F (55° C) and remain there for several days or weeks. Temperatures above 131°F for 72 hours are necessary to destroy human pathogens and most plant pathogens. Extremely high temperatures are detrimental to the composting procedure.
How
to Compost
The practices of composting animal mortality are simple. You start by constructing
a base of sawdust or acceptable amendment at least one foot thick. This base
will collect fluids that are released during carcass decomposition. Next, place
the carcass on the sawdust base. Cover the carcass with 1 to 2 feet of damp
amendment. This cover acts as a biofilter for odor control around the pile and
insulates the pile to retain heat. When a new carcass is added to the pile,
hollow out a hole in the amendment, while maintaining 4 to 6 inches of amendment
over the carcass already in the pile. Place another carcass on the pile. Cover
the carcass with 1 to 2 feet of amendment. Adequate depth of materials on top
of the carcass should minimize odors and the risk of scavengers disturbing the
pile. To decrease composting time and to allow the carcass to be laid flat,
the body cavity of the animal can be opened.
Facility
site is important to successful composting. A site must be selected so that
surface and ground water sources will not be adversely affected. It is beneficial
to locate the facility away from neighbors and human dwellings. The facility
should be away from the production unit to lessen the risk of disease transmission
by rodents. The composting pad should be firm but does not need to be paved.
A roof may or many not be necessary. A tarp can be used to cover the pile during
periods of excessive rainfall. Usually only one bid is needed for a small flock
of sheep.
Suggested Additional Reading
Disposal Methods of Livestock
Mortality - University of Nebraska
[PDF]
Management of Animal Mortality in Georgia
[PDF]
Composting Animal Mortalities - University of Minnesota
[PDF] On-Farm Composting
of Livestock Mortalities - Washington State
Disposing
of Dead Goats -- by Dr. Mark J. Estienne
Composting
Dead Sheep -- by David. L. Greene
Animal Disposal-The
Environmental, Animal Disease, and Public Health Related Implications: An Assessment
of Options
