When animals die or are slaughtered on farms,
carcasses and parts that are unfit for use as food should be disposed of
properly. Safe and environmentally responsible disposal of animal
carcasses, whether an individual death or during significant mortality
events, is an essential consideration. Premises should be promptly
cleaned in a manner that prevents any infectious or toxic health hazard
to domestic or wild animals or people. Information on the safe and
lawful disposal of carcasses can be obtained from local environmental
protection agencies. When the circumstances under which death has
occurred suggest a transmissible disease or toxic hazard, the nearest
animal health official should be notified immediately.
As general precautions, persons handling carcasses and
disinfectants should wear protective clothing and be properly equipped
to complete the tasks of disposition and disinfection. The method of
disposal should preclude contamination of soil, air, and water. Hides
and other parts of animals that have succumbed to infectious diseases or
toxins should be safely disposed of and not retained for use.
There are restrictions on carcass disposal for cattle
≥30 mo old because of specified risk materials (tissues in which prions
that cause
bovine spongiform encephalopathy [BSE] concentrate). Sheep or cattle diagnosed with or suspected of being affected by
scrapie (see
Scrapie) or BSE (see
Bovine Spongiform Encephalopathy),
respectively, must not be rendered. The preferred means of disposal for
these animals is incineration, although they may also be buried (
see below).
Rendering
Ordinarily, rendering is a safe, rapid, and economical
method of disposal of carcasses. Renderers are required to use
equipment and methods that prevent health hazards. Local regulations
specify requirements for transportation of carcasses to rendering
plants. During transportation, biosecurity must be considered to avoid
spreading infectious agents into the environment.
Burial
When a site acceptable to the local environmental
protection agency is available, burial is usually the preferred method
of disposal. In selecting a burial site, it is necessary to consider the
adequacy of soil depth and to avoid underground electrical cables,
water pipes, gas pipes, septic tanks, and water wells. The prevention of
secondary toxicosis or exposure to infectious agents to scavengers or
groundwater must be considered (eg, the burial of a carcass infected
with blastomycosis could potentially contaminate the soil thereafter).
The burial pit or trench should be at least 2.3 m wide and 3 m deep (7 ×
9 ft). The pit is a cave-in hazard and must not be entered without
proper shoring, and any other appropriate precautions should be taken.
At this depth, 1.3 m2 (15 ft2) of floor space will
accommodate a mature bovine or equine carcass, 5 mature pigs or sheep,
100 mature chickens, or 40 mature turkeys. For each additional meter (3
ft) in depth, the number of animals per 1.3 m2 of floor space
may be doubled. Contaminated litter, soil, manure, feed, milk, or other
material should be placed in the pit with the carcasses and covered
with at least 2 m (6 ft) of soil. The covering soil should not be
compacted. Decomposition and gas formation cause cracking, bubbling, and
leaking of fluids from a compacted burial site. The soil should be
mounded and neatly graded.
Burning
Burning in an incinerator that is operated in
compliance with local laws and ordinances is an excellent means to
dispose of one or a few carcasses and is the preferred means for sheep
with scrapie and cattle with BSE.
Burning carcasses in an open site should be done only
when legally permitted. Burning poultry carcasses should be considered
only when burial is not feasible. The burn site should be away from
public view and on flat, open ground that is clear of buildings, hay or
straw stacks, overhead cables, and shallow underground pipes or cables.
Locations upwind from houses, farm buildings, roads, or populated areas,
and those from which precipitation runoff may contaminate the
environment, should be avoided.
Carcasses must be placed on a quantity of combustible
supporting materials sufficient to reduce them completely to ashes. The
material must also be arranged in a manner to permit an adequate flow of
air to the fire. Gasoline or other highly volatile combustible liquids
should not be used.
To prepare the fire bed, an area of ground should be
staked out to accommodate the number of carcasses to be burned: 8 × 3 ft
for each mature cow or horse, 5 mature pigs or sheep, 100 mature
chickens, or 40 mature turkeys. The fire bed burns best if at a right
angle to the prevailing wind.
Under favorable conditions, burning should be complete
in 48 hr. Additional combustible material should be added as needed.
When the fire has died out, the ashes should be buried and the area
cleaned, graded or plowed, and prepared for seeding.
Other Disposal Methods
Composting, fermentation, and dry extrusion methods
have been developed to process certain dead animals and animal waste,
destroy pathogenic organisms, reduce volume, and produce feedstuffs.
Local environmental protection agencies and state agriculture
departments should be consulted concerning the acceptability of these
and other possible alternative disposal methods.
Disinfection of Premises
Removal and safe disposal of manure, feed, and debris
by burial or burning, followed by thorough scraping and cleaning of all
buildings and equipment, must precede the application of chemical
disinfectant. Except for steam cleaning, cleaning with aqueous solutions
is practical only at temperatures above freezing. A cleaning agent such
as trisodium phosphate or sodium carbonate dissolved in hot water will
facilitate cleaning. All traces of the cleaning agent must be rinsed
away with clear water before disinfectant is applied. Provision must be
made to contain and safely dispose of cleaning solutions, rinse water,
and disinfectant.
Disinfectants recommended for general use on surfaces
free of organic matter are sodium or calcium hypochlorite (1,200 ppm
available chlorine), iodine, phenol, and quaternary ammonium compounds.
Newer disinfectants use a combination of products (eg, quaternary
ammonia and glutaraldehyde) to enhance efficacy. Information on
disinfectants for specific animal disease agents can be obtained from
state or federal animal health agencies. Disinfectants should bear the
approval statement of the Environmental Protection Agency in the USA or
of a similar agency in other countries. Label instructions for
application must be followed.