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University of Wisconsin-Extension
When
temperatures and humidity begin to rise in Wisconsin, keep
a close eye on livestock. Temperatures in the high 80s and
the 90s can cause problems, as well as a 75 degree F. day
coupled with high humidity. Heat stress can cause general
discomfort, decline in animal performance and animal death.
- If
animals are kept outside, provide shade during hot weather.
Heat from the sun is a major culprit in overstressed
animals.
- Swine
may sunburn during hot, sunny weather. Try to keep them
out of the sun. Sun shades can cut the radiant heat load
by as much as 40 percent; ask your county Extension agent
for information on their construction. Pasture wallows are
also effective for sunburn protection and wet skin cooling.
- Turn
cows outside at night to cool them and cool the barn. Since
animals cool themselves primarily through breathing, barns
tend to get warm and humid quickly.
Ample
drinking water is vital to animals during hot and humid conditions.
Animals cool themselves by panting (water loss from the lungs)
and through water evaporation from the skin. Increased respiration
during hot weather is especially important for pigs and other
animals that do not sweat. Animals must replace the water
loss to cool themselves.
- Maintain
access to water. Provide automatic drinking cups so
animals can meet their requirements during hot weather.
- Keep
water containers clean.
- Adjust
the drinking space for the size and number of animals in
the pen or group. Excessive volumes of water grow warm
and stale throughout the day. (See the fact sheet "Livestock
Water and Nutrition.")
- Check
the water delivery systems periodically for plugs or other
problems.
- If
necessary, spray water on animals to cool them.
Proper
ventilation helps maintain livestock health during hot and
humid weather. Without adequate air exchanges and airflow
distribution within livestock buildings, heat and moisture
accumulate and animal production is affected. Contact a ventilation
specialist to inspect and update your system, if necessary.
Your county Extension office also may be able to help you.
- Use
the temperature humidity index as a guide to heat stress.
Listen to local or regional weather reports for the
temperature humidity index (THI) for your area. Some levels
of concern include:
a)
Above 75 THI - Heat stress on high-producing cows begins
to decrease feed intake and lower milk production.
b)
Above 80 THI - Severe heat stress may occur for cows on
pasture. Shade and adequate ventilation are essential
to minimize milk loss.
c)
Above 83-85 THI - Danger of fatal heat stress occurs.
- Keep
an eye on animals. If heat stress is a concern, check
animal temperature. Dairy cow temperatures approaching 104
to 106 degrees F. are dangerous. At 107 degrees F., spontaneous
heart failure is possible. Call a veterinarian and use methods
listed above to keep animals cool.
Additional resources:
Your county agricultural agent, ventilation specialists, your veterinarian
Related publications:
UW-Extension publications-
"When Temperatures Go Up, Does Your Milk Production Go Down?" (A2881);
"Cooling Swine," (PIH87). Midwest Plan Service publications- "Heating, Cooling and Tempering Air for Livestock Housing," (MWPS-34);
"Mechanical Ventilating Systems for Livestock Housing," (MWPS-32).
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NASD Review: 04/2002
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