Heat Stress in Cattle

This time of year, the beginning of August, can be the start to some of the hottest weather of the summer. Making sure you are well hydrated is important to keep healthy, that is the same mindset we should have when it comes to cattle. Heat stress has the greatest impact in North Dakota when the cattle are exposed to elevated temperature and humidity for a period of time. With the nights dropping down to the 60s, that will give cattle the chance to cool off and to prepare for the next day. Being proactive is the best way to deal with possible heat stress in cattle, but having a management plan in place is important as well. If the weather is changing and you anticipate heat stress conditions, monitoring temperature and humidity forecast will be important. Mammals have an involuntary method of regulating their body temperatures, including shivering and sweating a constant body temperature. Signs that we will see during the summer for mammals trying to maintain a constant body temperature are increased respiration rate, increased heart rate and increased panting. Here are some steps to follow to protect animals from heat stress;

- Identify animals that are most susceptible. Those animals are very young, very old or ones with dark hides.

- Develop an action plan to deal with heat stress

- Know when to intervene. A combination of temperature and humidity will be the determining factor of heat stress

- Having mounds in pens will help the cattle get access to wind

- cool the ground and the cattle gradually. Set up the sprinklers well in advance if there are hot and humid days in the forecast. Be aware of the droplet size, small droplets will turn into a mist and raise the humidity.

- Provide shade if possible

- Add light-colored bedding (corn stalks or hay) to reduce the temperature of the ground

- Control flies as much as possible, flies will add to the stress of the animal on hot days

- Do not work cattle during temperature extremes. If you need to move cattle, keep the time as short and calm as possible.

When developing an action plan for cattle that may develop heat stress, that should include;

Give each animal access to at least two inches of linear water through space in a pen. This means if you have a pen with 200 animals, you need 400 inches of linear water. If your pens only have small water troughs, add temporary space for additional water during the summer months.

Evaluate your water supply lines and ensure you have enough water pressure and flow capacity to keep tanks full at all times.

Move the animals’ feeding times to late afternoon or evening; that allows the rumen fermentation to happen during the coolest hours of the day.

Provide adequate air movement. Remove unessential wind barriers during the summer months (wind panels, equipment, weeds and other objects)

The U.S Department of Agriculture has a heat stress forecast tool at http://www.ars.usda.gov/npa/marc/heatstress, which is a great tool to use. This information is from the NDSU Extension Service, Gerald Stokka and Carl Dahlen. For more information dealing with heat stress on beef cattle operations go to http://tinyurl.com/beefheatstress.