Managing Heat Stress in
During the summer months, heat stress in cattle can result
in poor animal performance. Hot, humid weather creates dangerous
conditions for all livestock, particularly heavy-fed cattle. Dark-coloured
beef cattle on a high-energy diet, carrying lots of body condition,
will be the first affected by heat and humidity.
Be aware of heat stress and what to do about it. Use the cattle
and water management tips below to help minimize the impact of
heat stress on cattle.
If possible, keep current on marketing finished cattle at
the start of the hot months of summer. Monitor hot weather,
as it affects intake and performance. See the OMAFRA website
for additional information.
Space and shade availability become critical during severe
heat conditions. For normal conditions, Guidelines for Housing
Beef Cattle, a Canada Plan Series publication, recommends:
2.5 m2 (27 ft2) per head on slatted
2.8 m2 (30 ft2 ) of barn and 4.6 m2
(50 ft2 ) yard space per head with a barn and paved
2.8 m2 (30 ft2 ) of barn and 28 m2
(300 ft2 ) yard space per head with barn and dirt
In excessive heat situations, increase your shaded area to
allow cattle to spread out. If a shed is available, too many
cattle may crowd in looking for shade. Find ways to create temporary
Maximize airflow to all cattle, and especially those most
susceptible. Open up barns if possible and use fans to move
air, doubling winter ventilation rates to 5.7 cubic metres (200
cubic feet) per minute.
Avoid peak daytime temperatures when working cattle. Truck,
work or process cattle early in the morning or late in the evening.
Try to avoid movement between 8 am and 8 pm, since working cattle
will raise body temperatures.
Adjust the feeding schedule, shifting daily feed delivery
toward evening. This puts rumination and its associated heat
production in the cooler hours of the evening.
Monitor weather forecasts for high-alert conditions. High
temperatures, high humidity and low wind speed can be a deadly
When the temperature/humidity index reaches the Caution and
Warning categories (see Figure 1, above), watch cattle closely
for signs of heat stress and stroke. Excessive respiration or
panting, bunching (trying to reduce solar radiation), dullness
and a stumbling gait may be indicative of heat stroke. Animals
with rectal temperatures of 40°C are in immediate danger
and will require immediate cooling. Emergency slaughter is a
possibility, but there is a higher incidence of dark cutters
in heat-stressed cattle.
Temperature/Humidity Index. (Livestock Trucking Guide,
Livestock Conservation Institute)
equivalent of Figure 1
Adequate water supply must be available at all times. Finishing
steers will require up to 76 L (20 gal)/ head/day. Usually
0.4 m2 (4 ft2) of water surface per 100
head is adequate, but daily demand may double during hot humid
periods. If cattle are crowding existing water sources, consider
placing extra stock tanks in pens.
Wetting down the pen or mound surface will help give cattle
a cooler place to lie down. In emergency situations, try to
shade the ground and move animals to a cooler surface if possible;
grass is cooler than bare ground, which is cooler than concrete.
Set up sprayers or sprinklers to wet down cattle. In a pinch,
a hose and sprinkler running on and off every 20 min during
the hottest part of the day will alleviate some stress and associated
death loss. This increased evaporation helps lower the cattle's
Note: Wetting cattle or pen surfaces may require
an additional 38 L (10 gal) of water/animal/day or more! Do you
have a large enough supply of water to do this?
Hot, humid days will create problems for heavy cattle on
Have an emergency plan in place - water and shade sources.
Monitor weather reports and try to alleviate heat stress
on most susceptible cattle.
If cattle are showing signs of heat stroke, reduce animal
For more information:
Toll Free: 1-877-424-1300