Chute N The Bull

Heat stress can greatly impact cattle producers through decreased milk
production and subsequent calf growth, decreased reproductive
performance in cows and bulls, and decreased stocker and feeder
performance. It has been estimated that heat-related events in the
Midwest have cost the cattle industry over $75 million in the past 10
years. As summer approaches, make preparations to reduce the risk of
heat stress in your cattle.
The ideal temperature range for beef cattle is between 41° F and 77° F.
When temperatures exceed this, cattle are at risk of heat stress. Many
environmental factors affect the potential for heat stress, including
relative humidity, wind speed, solar radiation, ground cover, access to
water, diet, shade and nighttime temperatures. In addition, individual
animal characteristics can contribute to heat stress. These include hide
color, breed, health, adaptation, hair coat length and disposition. When
a combination of these factors and ambient temperature cause an animal's
heat load to exceed its ability to dissipate that heat, heat stress
occurs.
Identifying Heat Stress
When heat stressed, cattle exhibit many physical and behavioral changes.
Heat-stressed animals will have increased body temperatures, increased
water consumption, decreased feed consumption and decreased weight
gains. These changes may be subtle and difficult to recognize or
impractical to measure. Fortunately, there are many signs of heat stress
that are easy to recognize. The most obvious are cattle congregating in
shady areas or standing in ponds, and decreased grazing activity. You
may also notice cattle panting. According to the USDA's Agricultural
Research Service, more than 90 breaths per minute is an indication of
heat stress, and a respiration rate over 110 indicates a dangerous heat
stress level.
Tools are available to help producers identify conditions that are
potentially dangerous for cattle. The Livestock Weather Hazard Guide
provides guidelines that indicate the potential of heat stress at
different temperatures and relative humidity.
Another way to monitor heat stress conditions in your area is the Heat
Stress Forecast. The USDA has developed a Web site that reports heat
stress forecasts for the central United States. These forecasts provide
a more accurate prediction because they account for wind speed and solar
radiation in addition to temperature and humidity. This Web site can be
found at: www.ars.usda.gov/Main/docs.htm?docid=17130.
Managing Heat Stress
Provide fresh, clean water to cattle at all times. Water intake
increases during times of heat stress, so make sure that piped water can
refill tanks fast enough to keep up with cattle demand. If ponds are the
only source of water, monitor water quality throughout hot, dry periods.
Be sure that cattle have adequate shade. If shade is limited, heat
stress can be compounded by animals crowding together.
If possible, avoid working and transporting cattle during periods of
heat stress. If cattle must be worked or rotated to a new pasture, do it
as early as possible in the morning.
Heat stress can also affect the reproductive performance of cows and
bulls so plan your breeding season to avoid the hottest months. Keep in
mind that heat stress can impact semen quality for up to eight weeks.
Be prepared by planning now for heat stress. As hot weather approaches,
monitor the Heat Stress Forecast or use your local conditions with the
Livestock Weather Hazard Guide to determine the potential for heat
stress in your cattle. You can find this and past articles on the web
at www.mycountrytractor.com for your reference. Extension programs
serve of all ages regardless of socioeconomic level, race, color, sex,
religion, disability, or national origin. The Texas A&M University
System, U.S. Department of Agriculture, and the County Commissioners
Courts of Texas Cooperatings serve of all ages regardless of
socioeconomic level, race, color, sex, religion, disability, or national
origin. The TeAgriculture, and the County Commissioners Courts of Texas Cooperating




Thank you,
Tommy Neyland
County Extension Agent
Texas Agrilife Extension Service
P.O. Box 188
Centerville, Texas 75833
903.536.2531 phone
903.536.3804 fax