How to Combat Heat Stress in Cattle

Did you know cattle are at increased risk of heat stress in warm weather? When temperatures hit 80°F or higher, it is important to watch for signs of heat stress in cattle and take immediate action if they show symptoms. Early intervention is key, especially when your animals are trying to cool down after a hot day or if overnight temperatures reach 70°F or above. This guide will help you protect your herd from heatstroke and other heat stress effects on cattle.

Signs and Symptoms of Heat Stress in Cattle

Early detection plays an important role in preventing heat stress. One way to help detect symptoms earlier is by understanding the environmental factors that can negatively impact your herd’s health. In addition to sustained high temperatures, humidity is another factor to watch out for — especially in areas with high rainfall. If the Temperature-Humidity Index (THI) is above or projected to exceed 80 THI, then heat stress may be an issue. Other weather parameters to monitor include wind speed and cloud cover.

In these conditions, it’s important to watch cattle for the following signs of heat stress as defined by the USDA’s Agricultural Research Service.

Cattle do not sweat effectively and instead rely on respiration to cool themselves, accumulating heat throughout the day and dissipating it at night. Another way to test whether your cattle are showing signs of heat stress is to check their stress category as defined by predicted breathing rate:

How to Prevent Heat Stress in Cattle

Fortunately, there are many ways you can prepare for and prevent heat stress in cattle if you encounter less-than-ideal weather conditions during the summer months.

Avoid handling, transporting, or processing cattle on hot days as working the animals will elevate their body temperatures. If absolutely necessary, work them in the early hours using low-stress techniques. Similarly, heat production from feeding peaks 4-6 hours after intake. Feed cattle after ambient temperature drops, so their heat production doesn’t peak in the middle of the day when environmental temperatures are also at their highest point.

Provide ample access to clean and cool water. Consider increasing tank capacity or adding extra waterers. Keep water sources between 40 and 65°F and make sure the water is clean and free of contaminants. Make sure to have a backup plan in place in the event the power or water systems fail.

Provide adequate shade, especially for dark-haired, heavy, young, or older cattle. Likewise, remove barriers to wind from pastures. If your cattle are in enclosed buildings to be fed or housed, use cooling supplies like fans to make sure they receive enough ventilation. In certain situations, sprinklers or misters can be used intermittently to cool cattle during times of stress. However, when the air is already full of moisture, the mist cannot evaporate quickly enough. Thus, the cooling effect is diminished. You should also avoid using sprinklers indoors because without enough airflow, they can worsen conditions by creating more humidity.

If heat stress is a concern, observe cattle for abnormal behavior, including changes in movement and location. Then move affected animals to cooler areas with reduced stocking density.

Heat Stress vs Heat Stroke in Cattle

Heat stress can turn into heat stroke in animals with other health issues or those that have been impacted by heat stress for a prolonged period. Cattle experiencing heat stress may show signs of open-mouth panting and shallow breathing while standing. Cattle experiencing heat stroke will not rise and usually appears unresponsive or have dilated pupils. The animal will also feel hot to the touch.

On the worst days, normal cattle may have elevated temperatures in the range of 103°F when coming in from pasture or in a barnyard gathered together. Typically, heat stroke happens if a cow’s internal temperature is 106°F to 108°F. In these cases, quick intervention is key to make sure your animal will fully recover. A recommended course of action for heatstroke is to continuously hose the animal down with cold water from head to tail for 20 to 30 minutes. IV fluids may also be required.

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Sources:

Michigan State University Extension

Iowa State University College of Veterinary Medicine

Eco Farming Daily

University of Nebraska Institute of Agriculture and Natural Resources