Warm weather has returned, bringing the risk of heat stress in livestock. Cattle in feedlots or other confinement settings are often at greatest risk, especially those near finished weight, but pasture cattle, bulls, calves, sheep, goats, and other livestock can all be affected when high temperatures, humidity, low wind, and warm nights stack together. Heat stress is driven by more than temperature alone. Humidity, wind, sunlight, and whether animals can cool down overnight all play a role.
A couple of tools can help producers monitor risk before animals are already in trouble. The Nebraska Mesonet Adult Cattle Comfort Index uses real-time weather station data to estimate cattle comfort levels across the state. The USDA Agricultural Research Service also has cattle heat stress forecast resources from the U.S. Meat Animal Research Center at Clay Center. Producers can find these by searching “Nebraska Mesonet cattle comfort index” or “USDA ARS cattle heat stress forecast.”
Preparation should start before the heat arrives. For cattle in pens, consider marketing finished or nearly finished cattle ahead of a major heat event. If that is not possible, move high-risk cattle to pens with better shade, airflow, water access, or bedding options. High-risk groups include finished or heavy cattle, dark-hided cattle, high-intake animals, livestock with previous health issues, and pens or pastures with limited water, shade, or airflow. Bulls are also worth watching, as heat stress can affect fertility for several weeks.
Water is the most important piece of heat stress management. Make sure tanks are clean, water flow is adequate, and animals have room to drink without crowding. In pens, temporary tanks can help spread cattle out. In pastures, check tanks, pipelines, ponds, and automatic waterers to be sure they can keep up with demand. Weak water flow may not be noticed until animals are already under stress.
Shade and airflow also matter. Shade needs to be large enough to avoid crowding and high enough to allow air movement. Poorly designed shade can concentrate animals and make conditions worse. In pasture settings, natural shade can help, but make sure water access is not forcing animals to travel long distances during the hottest part of the day. In feedlot pens, sprinklers can help when used correctly and started before cattle are in severe distress.
Limit handling during extreme heat. Avoid receiving, processing, sorting, hauling, rotating, or moving animals during the heat of the day. If livestock must be worked, do it early in the morning and keep the process quiet and low stress. Evening may feel cooler to us, but cattle may still be carrying heat from earlier in the day. For feedlot cattle, also avoid large or sudden feed changes. Storm rations or diets with more roughage may help lower metabolic heat load, while added fat should be avoided during extreme heat.
Signs of heat stress include open-mouth breathing, excessive salivation, bunching, restlessness, standing rather than lying down, and crowding around water or shade. Severe cases may become weak, uncoordinated, or go down. Once severe signs appear, options are limited, so prevention and early response are key.
Heat stress is serious, but preparation makes a difference. Watching the forecast, using heat stress tools, maintaining water, improving shade and airflow, reducing handling, and identifying high-risk animals can all help limit losses. For questions specific to feedlot heat stress, Dr. Alfredo DiCostanzo, Nebraska Extension Beef Systems Educator in Cuming County, is a great resource. He can be reached at 402-372-6006 or by email at adicostanzo3@unl.edu.
Ben Beckman is a beef systems Extension Educator serving northeast Nebraska. He is based out of the Cedar County Extension office in Hartington. You can reach him by phone: (402) 254-6821 or email: ben.beckman@unl.edu.
