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Drovers | Protecting Cattle From Summer Heat

May 24, 2024By: Dr. Kelsey Bruno-Bayliff, Ph.D., Farm Standards & Science Coordinator

As daily temperatures begin to increase, foreshadowing the prolonged hot weather and heat stress events of the summer, now is the time to prepare facilities to protect cattle from the summer heat.

The incoming heat can negatively affect animal growth performance, fertility, and animal welfare, but taking these management precautions can help to reduce the impacts of anticipated and extreme weather conditions.

Offer plenty of clean water (Hydration is the key to success)

Cool, clean drinking water can help cattle thermoregulate in severe temperatures. Depending on the size of the cow, its age and lactation stage, and the ambient temperature, a mature cow can consume up to 30 gallons of water a day.

Plenty of clean water should be offered in multiple locations so that all animals can easily access it, including the lower-ranking cows. This can be achieved by preparing additional water troughs or containers. Water should be kept in the shade so that the temperature of the water stays cool. The location of water should be familiar to the animals before heat stress events so that it can be easily found, and they should not have to travel too far to access it.

For added support, supplement water with an electrolyte source or rumen stabilizer in their water or feed before forecasted heat stress events. While not as helpful once the event has begun, these supplements can be used before heat stress to proactively decrease the severity on the animals.

Provide shade

During hot weather and heat stress events, animals should be provided shade to escape the sun and allow for more effective cooling. Shade can be offered in many ways, including constructed shelters, trees with large canopies, shelterbelts (thick lines of hedges or trees), or temporary shade shelters. When providing shade, it is important to consider the direction of the shade throughout the hottest parts of the day and ensure that enough shaded space is provided so that all animals can utilize it without crowding.

Avoid handling or transporting

Handling or transporting animals during hot weather should only be performed if necessary, as these activities cause additional physical stress for the cattle. For example, handling cattle during hot weather can increase body temperature by 0.5 to 3.5 degrees Celsius (0.9 to 6.3 degrees Fahrenheit).

If handling or transporting cattle is required during the summer months, it should be performed as early in the day as possible while temperatures are lower and not after 10 a.m. This may require some planning ahead for preventative health programs, such as vaccination plans and fly control, to limit handling during the hottest times. Additionally, if transporting is absolutely necessary, transport stocking densities should be decreased to 85% of capacity to ensure good ventilation, and drivers should have contingency plans in place in the case of extreme weather.

Improve airflow

Improving airflow can help the cow’s cooling process and decrease the severity of heat stress. Air exchange can be provided through mechanical means, such as ventilation systems or fans, or naturally, by allowing fresh air movement. Winter windbreaks should be removed to allow for more natural airflow.

Sprinklers in dry conditions

Sprinklers can be helpful to cool cows during hot, dry weather due to the cooling effect the cow experiences when moisture from a sprinkler evaporates from their skin. However, this method can cause an increase in relative humidity, generating other unwanted effects or impacts of heat stress, and should only be used when humidity is low.

Other considerations to take when using sprinklers include avoiding excessive use and cycling the sprinklers on and off so that the water may evaporate more efficiently.

Monitor weather

By monitoring weather patterns, we can prioritize the times that cattle may need the most support.

Evaluate heat stress events by checking incoming ambient temperature and relative humidity. Monitoring the temperature humidity index (THI) can also be beneficial in preparing for heat stress events, but measuring THI can be hard to do. For that reason, there are publicly available tables on the market that outline THI and heat stress severity based on the area’s temperature and humidity values.

Some states, such as Oklahoma, and Kansas, have publicly available Cattle Comfort Index (CCI) values from their local Mesonet services. This information is collected in real-time and reflects the experience of the cow in its environmental conditions.

Identify heat stress

There are many signs of heat stress in cattle, but some of the common signs include:

  • Increased respiration rate
  • Crowding around water sources
  • Panting, open mouth in more severe cases
  • Increased water intake
  • Loss of appetite
  • Lethargy
  • Increased salivation
  • Unconsciousness, in severe cases

High-risk animals

The animals at highest risk for heat stress are young cattle, dark-hided cattle, and unhealthy cattle. Additional cattle that may be at high risk are cattle without shade, newly received, mixed lightweight cattle, or lactating cows.

By implementing these short-term planning and preparation steps, the long-term negative consequences of heat stress on cattle can be alleviated.

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