David
E. Baker and Rusty Lee
University of Minnesota Extension Service
Few
farmers view livestock as a source of danger. Yet animal-related
accidents cause numerous deaths and serious injuries each
year. A recent National Safety Council study ranked beef cattle
farms second and dairy operations third among all farming
enterprises in injuries per hours of work. Seventeen percent
of all farm injuries involved animals. This equaled the percentage
of injuries caused by farm machinery.
Removing
hazards brings you one step closer to a safe work environment.
Whether you are operating equipment or working with animals,
taking a few precautions and observing safety rules can save
you precious time, prevent injury, or even save your life.
Anyone who works with livestock knows each animal has its own
personality. Animals sense their surroundings differently than
humans. Their vision is in black and white, not in color. They
also have difficulty judging distances. And differences exist
between the vision of cattle, swine and horses. For example,
cattle have close to 360-degree panoramic vision (Figure 1).
A quick movement behind cattle may "spook" them.
Animals
have extremely sensitive hearing and can detect sounds that
human ears cannot hear. Loud noises frighten animals, and
research proves that high-frequency sounds actually hurt their
ears. These factors explain why animals are often skittish
and balky, particularly in unfamiliar surroundings.
Watching
animals for signs of aggressiveness or fear alerts you to
possible danger. Warning signs may include raised or pinned
ears, raised tail or hair on the back, bared teeth, pawing
the ground or snorting.
Although
handling methods may vary greatly for different types of livestock,
there are some generally accepted rules for working with any
animal:
- Most
animals will respond to routine; be calm and deliberate.
- Avoid
quick movements or loud noises.
- Be
patient; never prod an animal when it has nowhere to go.
- Respect
livestock - don't fear it!
- Move
slowly and deliberately around livestock; gently touch animals
rather than shoving or bumping them.
- Always
have an escape route when working with an animal in close
quarters.
Many
livestock handling injuries are directly related to equipment
or building structures. Poor facilities and equipment can also
cause injuries to animals. This can mean considerable economic
loss at market time.
Tripping
hazards such as high door sills, cluttered alleyways and uneven
walking surfaces can cause serious injury and a considerable
amount of lost work time. Studies have found that falls account
for 18 percent of all animal-related accidents.
Concrete
floors are best for livestock. The finish on concrete floors
should be roughened to prevent slips under wet conditions.
High traffic areas, such as alleyways, should be grooved.
Floors should allow water to drain easily. Slatted floors
often are used to keep animals dry in a confinement system.
Fencing
and gates should be strong enough to contain crowded livestock.
A variety of materials are available, but the key is strength
and durability. A protruding piece of lumber, a nail or a
bolt can cause painful and infectious injuries. If backed
or pushed into, one of these objects can cause a serious back
injury.
Alleys
and chutes should be wide enough to allow animals to pass,
but not wide enough to allow them to turn around. A width
of 30 inches is recommended for a cow-calf operation. For
cattle in the range of 800 to 1,200 pounds, a 26-inch width
is recommended. Solid wall chutes, instead of fencing, will
lower the number of animals that balk in the chute.
Lighting
should be even and diffused. Bright spots and shadows tend
to make animals more skittish, especially near crowding or
loading areas. Animals move more readily from dark areas into
light, but avoid layouts that make them look directly into
the sun.
Handling
equipment can speed up livestock confinement work operations,
reduce time and labor requirements, cut costs, and decrease
the risk of injury.
Hygiene
is vital to good livestock management, particularly in confinement
systems where diseases can spread quickly. Maintaining a clean,
dry environment is obviously important, but other factors also
are crucial.
Ventilation
should minimize dust. Various molds that can cause respiratory
as well as digestive problems may be present in feed. All
feeds should be carefully checked before they are fed to livestock.
Deal only with reliable feed dealers and have suspect feed
tested.
All
animals, domesticated or wild, can be a source of human illness
and parasitic infestation. Diseases that can be transmitted
between animals and people are referred to as zoonoses.
Rabies Rabies is
a deadly virus that affects the central nervous system. It can
be transmitted by saliva from an infected animal through a bite,
open wound or sore. Although widespread pet inoculation has
greatly reduced the threat of rabies, rural people are at greater
risk due to their proximity to wild animals. A veterinarian
should be called to examine animals observed acting abnormally.
Seek immediate medical attention if you are bitten by an animal
that you suspect is rabid.
Lyme
Disease (LD)Lyme Disease
(LD), while only a remote possibility in Missouri, is another
potential threat. Although the tick species known to transmit
LD are not present in the state, the organisms that cause LD
have been found in the Lone Star tick, which is found in Missouri.
It is not known at present whether this tick transmits LD to
humans. It may transmit LD to animals, but is known to do so
only in its nymphal stage when it is usually found on rodents,
birds and feral animals such as deer.
If LD
occurs, its symptoms may develop within 2 to 30 days of the
tick bite. A small red bump appears near the bite and enlarges
into a spreading red ring. This is followed by a general sickness,
including fever, chills, headaches and backache. Some may
experience palpitations, dizziness and shortness of breath.
LD responds
well to antibiotics in its early stages, but if left untreated,
it may advance into a chronic stage involving rheumatoid arthritis
or cardiac problems.
Brucellosis
(Bands Disease)Brucellosis
(Bangs Disease) affects cattle, goats and swine. It can be transmitted
to people in unprocessed milk, infected carcasses, or by an
aborted fetus or afterbirth from an affected animal. Good sanitation
practices reduce the chances that herds will be infected. Animals
should be tested periodically for this disease.
Trichinosis Trichinosis,
caused by tiny parasites, can be painful and sometimes fatal
to humans. It is transmitted by consumption of uncooked or partially
cooked pork. Trichinosis has nearly been eradicated in North
America. Thorough cooking is the best prevention.
Salmonella Salmonella
organisms are found in poultry and in wild and domestic animals.
They can be transmitted to people through contaminated food
or water. The disease can cause severe gastrointestinal distress
and fever. Prevention includes proper storage and cooking of
animal-derived foods. Good sanitation procedures when handling
food reduce the risk of salmonella poisoning.
Other
zoonoses also exist. However, preventive measures such as
keeping animal facilities clean, testing and immunizing, and
using sanitary practices in handling animals and their products
minimize the danger.
Toxic gases, especially in confined spaces such as manure pits,
silos and grain bins, can pose hazards to humans and animals
(Figure 2). Four gases of major concern can be found in manure
pits. They are hydrogen sulfide (H2S), ammonia (NH3),
carbon dioxide (CO2) and methane (CH4).
The
primary health hazards of these gases are:
- Toxic
or poisonous reactions that can occur in people or animals.
Hydrogen sulfide is the most toxic of these gases.
- Oxygen
depletion, which can result in asphyxiation. Hydrogen sulfide,
ammonia and carbon dioxide gases are all heavier than air.
During agitation of the pit and under conditions of poor
ventilation, these gases will replace the oxygen in the
air.
- Explosions
that can occur when oxygen mixes with the gases. This is
primarily a problem with methane.
Characteristics
Hydrogen
sulfide:
- Most
dangerous gas associated with waste decomposition.
- Distinct
rotten egg smell; heavier than air.
- After
breathing this gas a short time, sense of smell becomes
fatigued and you may no longer be able to detect any odor.
Gives a false sense of security. At low concentrations the
gas irritates the eyes and respiratory tract; at moderate
levels, causes headaches, nausea and dizziness; at high
concentrations, death will occur.
Ammonia:
- Distinct,
sharp, penetrating odor detectable at very low concentrations.
- Heavier
than air.
- At
moderate levels of concentration, can irritate eyes and
respiratory tract; at high concentrations, can cause ulceration
to the eyes and severe irritation to the respiratory tract.
Carbon
dioxide:
- Odorless,
heavier than air, difficult to detect.
- Primarily
replaces oxygen in air and acts as an asphyxiant. At moderate
concentrations, shortness of breath and dizziness can occur.
- A
major contributing factor to animal deaths by asphyxiation
in confinement buildings, which often occurs during ventilation
failure.
Methane:
- Odorless
and lighter than air, so it tends to accumulate near the
tops of manure pits.
- Considered
an asphyxiant at extremely high concentrations. Main hazard
is its flammable, explosive nature.
Under
normal conditions in a well-designed, properly constructed building
with good ventilation, you should not have many problems with
gas accumulation. But serious problems can occur if the proper
precautions are not followed.
- Provide
as much ventilation as possible in the pit and building
during agitation of the waste. Although pits are agitated
only a few times a year, most human and livestock deaths
or illnesses occur at these times.
- No
workers should be near the pit or in the building during
agitation. If possible, remove all animals from the building.
- Avoid
entering a manure pit at any time, if at all possible. Even
if the pit has been emptied, it still may be lacking in
oxygen or have high concentrations of toxic gases.
- Always
keep at least one foot of space between the highest manure
level and the slats. This protects the animals who lie on
the slats and inhale the gases that will accumulate at the
surface of the pit.
Grain, particularly corn, can accumulate high amounts of nitrates.
During the first 24 to 48 hours of fermentation, significant
amounts of nitrogen dioxide (NO2) can be released (Figure 3).
When this gas is inhaled by silo workers, it can cause a severe
chemical pneumonia known as "silo filler's disease."
Nitrogen
dioxide is one of the most hazardous lung irritants. It has
a pungent, sweetish odor, even in low concentrations of 5
parts per million (ppm). It has a reddish-brown color, visible
only when concentrations reach a dangerous level (75-150 ppm).
It is heavier than air and can settle at the bottom of enclosed
spaces.
Any
concentration over 25 ppm can be hazardous. The effect on
the lungs is often so subtle that the victim may not realize
the serious nature of the exposure until too late. Inhalation
of 50 to 75 ppm for 30 to 60 minutes can cause bronchitis;
50 to 100 ppm causes chemical pneumonia; 150 to 200 ppm, a
severe fibrosis type of pneumonia; 300 to 400 ppm, severe
lung damage, fatal in 2 to 10 days; over 500 ppm, acute pulmonary
edema, fatal in less than 48 hours.
- Do
not allow anyone to enter the silo during the filling process
until the blower has run for at least 30 minutes. The height
of the chute doors should be kept as close as practical
with the silage level. This allows heavier-than-air gases
to be blown down the chute.
- Do
not for any reason allow anyone to enter the silo for 7
to 10 days after the filling process is completed. It is
during this time that the fermentation process is occurring
and producing the toxic gases.
- Provide
good ventilation around the base of the silo during the
fermentation process so that the gases will be carried away.
- Provide
fencing to prevent children and animals from straying into
any spaces adjoining a silo during this dangerous period.
- When
the silo is opened, the blower again should run for a minimum
of 30 minutes before entry. Given a proper fermentation,
no further gas production should occur.
- Never
enter a silo without someone on the outside monitoring your
activity.
For
information about grain storage, see MU publication G01969,
Safe Storage and Handling of Grain.
Dusts
are the most common danger in the air when working around livestock.
Some types of dust are more dangerous than others. But all dust
can cause serious health problems to an individual, depending
on the amount, type and length of exposure.
Some
dust carries antigens that cause severe irritation to the
respiratory tract and lungs. This often results in lung damage.
The most common form is known as "farmer's lung." It results
from breathing moldy forage or grain, normally hay. Farmer's
lung is one of the most disabling diseases among dairy farmers.
Farmer's
lung symptoms often are not noticed until several hours after
exposure to the dust. Symptoms often are mistaken for bronchitis
or pneumonia. If the disease is not diagnosed early, irreversible
lung damage and sometimes death can result.
Farmer's
lung will limit the amount of work a farmer can do because
shortness of breath will require frequent rest periods.
"Nuisance
dust" is the term for other forms of dust that are often inhaled
while working with livestock. Breathing dusty air of this
type for long periods will cause areas of your lungs to become
hardened and inelastic, and your capacity to take in needed
oxygen will be reduced. Furthermore, your susceptibility to
respiratory diseases like pneumonia may increase.
- Store
only dry, well-cured forage or grain. Mold develops from
the heat generated by moist or wet stored forage and grain.
- Burn
moldy grain or hay.
- Keep
livestock areas as clean as possible to prevent dust from
collecting.
- Wear
a dust mask in dusty work areas to keep harmful dust out
of your lungs.
Foot
injuries are frequent in all types of livestock facilities.
Wear safety shoes or boots. Composition and type of sole configuration
also are important to combat the problems of uneven and wet
footing.
If you
must enter a manure pit or silo without a self-contained breathing
apparatus, turn on all forced ventilation equipment for a
minimum of 30 minutes.
Wear
a harness or tie a rope around your waist and have at least
one person holding the lifeline. If you are overcome by the
gas, this lifeline is your only means of rescue without endangering
other people.
A self-contained
breathing apparatus is recommended, but its high cost may
make it impractical to have this equipment readily available
on most farms.
- Liquid
manure holding facilities should be secured against entry.
Outdoor lagoons and ponds should be fenced.
- Good
housekeeping is essential, not only for your personal safety,
but also for the health and well being of your stock.
- Keep
children away from animals, particularly in livestock handling
areas.
- Most
male animals are dangerous. Use special facilities for these
animals and practice extreme caution when handling them.
- Be
calm and deliberate when working with animals. Always leave
yourself an "out" when working in close quarters.
- Respect
all animals. They may not purposely hurt you, but their
size and bulk make them potentially dangerous.
- Most
animals tend to be aggressive when protecting their young;
be extra careful around newborn animals.
- Stay
clear of animals that are frightened or "spooked." Be extra
careful around strange animals.
- Monitor
entry into your operation; sales and service personnel could
bring diseases from other farms.
- Keep
facilities in good repair. Chutes, stalls, fences and ramps
should be maintained regularly.
Disclaimer
and Reproduction Information: Information in NASD does not represent
NIOSH policy. Information included in NASD appears by permission
of the author and/or copyright holder. More
NASD Review: 04/2002
This
document is
GO1931
,
published by Missouri University Extension, the University
of Missouri-Columbia, Columbia, MO 65211. Publication date:
October 1993. Partial funding for this guide sheet was provided
by the University of Missouri-Columbia/National Institute for
Occupational Safety and Health Cooperative Agricultural Promotions
Agreement.
David
E. Baker and Rusty Lee, Department of Agricultural Engineering,
University of Missouri-Columbia, Columbia, MO 65211.
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