During hot weather, cattlemen need to track weather conditions, watch their cattle and take steps to prevent heat stress, says Heather Larson, South Dakota State University Extension cow-calf field specialist.
"Producers need to monitor all weather conditions, such as temperature, humidity and wind, closely; start interventions early in the day, well before noon," says Larson. "If an extended amount of time elapses before cattle are cooled down, it may be too hot and late."
Heat stress happens almost every summer, and its impact on livestock varies based on their genetic makeup, health status, stage of production and previous exposure to heat.
"Together, these factors can become deadly, when the combination of temperature, humidity, wind speed and cloud cover result in extreme environmental conditions," she says. "Watch cattle early for signs such as panting or open-mouthed breathing. These are indications that heat stress is occurring." And that's when producers should take actions to reduce that stre.
Avoid working, transporting or moving cattle during hot weather. "If it's necessary to work or move cattle, do so in the early morning hours only. Cattle are still dissipating their body heat during the evening hours."
Changing feeding times from morning to late afternoon shifts the heat produced by fermentation to nighttime, when cattle are better able to dissipate the heat.
"If you are feeding twice a day, then feed 60-70% of the total ration in the late afternoon and the rest in the morning," she advises.
Water intake decreases when water in the tanks exceeds 80°F, so ensure that water pipes are not exposed to sun. They should be at least 2’ underground. Adding a supplemental tank of water to pens of cattle is another safeguard.
"Remember, in the summer when many animals are drinking, many tanks will be trying to fill at one time in addition to other potential needs for water on the same water supply line," she says. "During the summer, water intake may exceed 9 gallons per head per day. It is recommended that cattle have a water space requirement of 1.5" per head. For example, 100 head of cattle would need 150” of water-tank perimeter."
Fly control becomes even more important in hot weather. "Cattle will group together to get away from biting flies. Under hot conditions this will aid in increasing heat stress. Provide fly control through the use of fly tags, sprays or other control methods."
Providing shade takes a substantial amount of stress off cattle. That typically isn’t an option, but giving shade to vulnerable animals such as those in the sick pen may prevent deaths. If using sheds, make sure there is adequate airflow. The weight and color of animals are additional considerations.
"Dark-hided and heavier cattle should preferentially be given pens with more airflow,” she says. “If pens near shelterbelts with poor airflow need to be used, stock them with lighter-weight, lighter-colored calves, if possible."
Sprinklers can help reduce heat stress, and Larson says large water droplets are more effective than a mist. "Water should run off the cattle, saturating the hair. Running the sprinklers for five to 10 minutes at a time, twice an hour, will allow evaporative cooling to take place and is preferred over continuous sprinkling."
Wetted-down pens will provide a cooler surface for animals to stand. If you have no way to sprinkle cattle to cool them and the ground, another option that may help is applying a layer of ground straw. It will absorb less solar radiation and provide a slightly cooler place to stand.
The USDA Agricultural Research Service's cattle heat-stress forecast pageforecasts out a week at a time to help producers prepare for conditions that may be harmful.
"With this tool and the management steps above, ranchers can prepare for extreme conditions and hopefully triumph over them," says Larson.