Summer is heating up and so are the cattle! Heat stress is a reoccurring issue in the summertime. Black hided, sick, or heavy-weight cattle are most susceptible to heat stress. When it comes to heat stress, it’s important to know the warning signs and what can be done to prevent it.
Signs
Heat stress typically arises when temperatures start to exceed 80F and 90F degrees. When it hits 80F cattle are moderately at risk for heat stress, and 90F places them in the high-risk category. Unlike humans, cattle do not sweat efficiently, and their rumen is a heat magnet inside of them. Some of the common signs of heat stress are panting, open-mouthed breathing, and excessive slobbering. You might also see cattle grouping together and actively seeking shaded areas.
Prevention
Heat stress cannot be completely prevented, but you can lessen its impacts. Following forecasts allows for time to prepare a plan of action to combat heat stress. Ensuring cattle have access to plenty of clean water during periods of hot weather is key. Waterers need to have a refill and flow rate that meets the increased needs of the animal. During periods of high heat, it is best to avoid working cattle. If you must handle, doing so in the early morning is best. Providing holding pens with shade, decreasing the amount of time cattle spend in holding pens, and moving them slowly reduces added stress. It is also a good option to reduce the percentage of feed given. By giving a lesser percentage of feed later in the day, the heat of digestion is moved to cooler parts of the day. Cattle that are battling flies are also at higher risk. The energy it takes to keep flies off creates extra heat for the animal. We also know that pastures with endophyte-infected fescue often cause vasoconstriction. In situations of high heat, this leads to reduced blood flow thus decreasing the cattle’s ability to disperse heat throughout the body.
Reducing Heat Stress
Ensuring cattle have access to shaded areas will help to reduce the effects of heat stress. Shade can lower the breathing rate and body temperature of the animal. It is recommended that shaded structures should be at minimum seven feet tall. Lowering the shade structure can reduce airflow and contribute to stillness in pens. Sprinklers can also be used to provide a cooling effect. Sprinklers are more commonly used in feedlot facilities, and using multiple sprinklers per pen can help eliminate grouping. Overcrowded barns and pens contribute to increased temperatures in covered facilities. If pens have dead air, any cooling effects can be offset by the humidity created.
Impacts
When cattle start to exhibit heat stress, production can be negatively affected. Feed intake declines as the animals heat up. This can lead to a drop in efficiency and performance. Average daily gain often declines, and it can be difficult to regain. These drastic changes in feed intake can also facilitate the development of illness due to the compromising of the immune system. Heat stress contributes to reproductive issues in both cows and bulls. Reduced breeding activity, early embryo loss, and decreased sperm quality are all seen in times of high heat. In extreme cases, heat stress can lead to death.
Summary
Periods of high heat cause a number of issues in cattle. Keeping cattle in shaded areas with increased airflow and access to adequate water assists in keeping the animals cool. Providing cattle with ways to combat the heat ultimately helps to decrease the negative effects heat stress has on production.
About the Author
Mabry Bruhn is a student at the University of Illinois Urbana-Champaign who works in beef production, research, and producer outreach as a University of Illinois Extension intern in the I-BELIEF program through the Department of Animal Sciences in the College of Agricultural, Consumer and Environmental Sciences. This article has been reviewed by Extension Commercial Agriculture Educator, Travis Meteer.