MITIGATING WEATHER RELATED STRESS IN BEEF CATTLE

Julia Herman, DVM, MS, DACVPM Beef Cattle Specialist Veterinarian, NCBA, a contractor to the Beef Checkoff | October 25, 2022

As fall approaches, the heat of summer lingers in much of the country. Cattle across industry sectors continue producing with the resources provided to them. As the weather transitions from hot days to cool days, there are strategies to help cattle transition and cope with these weather stressors. The Beef Checkoff-funded Beef Quality Assurance (BQA) National Manual provides guidelines in handling cattle in varying weather and optimizing animal welfare.  

Grant Dewell, beef extension veterinarian at Iowa State University said, “Recognizing and preparing for weather stress ahead of time is critical as there is less a producer can do on short notice. Most mitigation strategies require prior planning and investment, such as shade structures or sprinklers, which producers should work into their yearly improvement plans.”  

Heat stress and cold stress each have specific approaches that cattle producers can adapt to their individual operations.  

Heat stress 

 By this time of year, hot days are no longer a surprise. Cattle producers managing cattle in feedlots or confinement are constantly assessing climate conditions to optimize the welfare of the growing cattle on their operations. This can include a variety of options depending on the yard’s facilities:  

• Pen rotation – Understanding the growth trajectory of pens can help determine where those cattle should be placed in the feedlot to maximize air circulation. This method requires planning and labor to rotate fat cattle, which are most susceptible to heat stress, to pens with the most air circulation.     
• Water – One of the most effective ways to mitigate heat stress in any cattle operation is to provide fresh water at an appropriate flow rate. During heat events, water consumption can increase two to three times normal rates, so evaluating drinking systems at the beginning of the summer is important. Extra tanks may be needed if individual waters or troughs are not providing enough space for the cattle. Be aware of aggressive animals that may not let other animals into water.  
• Sprinklers – Another investment that can be important in heat-stressed cattle, sprinklers can cool cattle through evaporative cooling and also cool the ground, thereby reducing radiant heat from the ground. Cost-to-benefit ratio of the sprinklers is a factor in deciding if these are right for your operation. During drought years, like this summer, diverting water to sprinklers may not be a good option. There are options to store runoff water for sprinkler systems, though research would be needed to ensure the water is clean and will not contaminate the feed or environment.  
• Shade – Providing shade is also an effective way to help cattle cope with heat stress. These physical structures must be designed to fit the yard or operation and maintained throughout the year which can be difficult.  
• Feeding schedules – Changing the feeding times can help reduce heat production in growing cattle. Heat production from feed intake peaks four to six hours after feeding, according to Dewell. Feeding bigger meals in the afternoon or evening will allow peak rumination temperatures to occur at night. Although it is controversial, backing the concentrate (and energy) out of a ration to decrease heat load has been shown to help.  
• Transportation – It is recommended to transport and load cattle during cooler times of the day. Planning schedules with weather reports and understanding wind speeds for proper ventilation is integral to cattle welfare during transport. Minimizing the time animals spend in handling facilities or waiting on the trailer are some mitigation measures. BQA discusses the Temperature Humidity Index (THI) which provides general guidance on using temperature and relative humidity to determine when to work or transport cattle.  

Heat stress is less of an issue for cattle on pasture for a few reasons. Cattle are not as finished as feedlot cattle and are able to dissipate heat more efficiently. They also can seek their own shelter or pick their own environment more readily which aids in heat stress mitigation. Shade trees or structures in or beside pastures can be a useful tool, given there is enough room for cattle to share space. Rolling hills can help cattle catch breezes depending on the time of day.  

In general, cattle on pasture do not exhibit death loss due to heat stress. A hidden impact, Dewell cautioned, can be on fertility of both cows and bulls during the breeding season. If weather conditions are too hot, bulls may spend energy and time seeking shade rather than breeding females. Without proper thermoregulation, both semen in bulls and ova in cows and heifers can be negatively affected. Early heat events during the breeding season may impact fertility which may not immediately be recognized. 

When setting up your breeding program, whether it is with natural service, artificial insemination or other advanced reproductive techniques, it is pertinent to evaluate weather forecasts and understand how that may affect the success of your breeding program.  

For any sector, producers and teams should be cognizant of working cattle during hot weather. As recommended by the guidelines outlined in BQA resources, work cattle more prone to heat stress first thing in the morning or early in the day, or later if conditions are moderate. Limiting the amount of time cattle spend in the handling facilities where heat stress may be more significant is important. When making decisions to handle cattle one should consider a number of factors including facilities, labor, temperature, humidity, wind speed and cattle disposition.  

Cold stress 

Fall weather brings cool evenings and then cooler days. Preparing for the stress of lowering temperatures can improve success on an operation. BQA reminds us that cattle exposed to cold weather have increased energy requirements and considering weather in addition to life stage will help producers plan for the winter months ahead. The lower critical temperature (LCT) is when cattle start using energy to maintain their body temperature and feed needs adjustment to offset that loss. Moisture versus dry coat also plays a role in performance needs. Some factors to consider include:  

• Shelter – Windbreaks and shelters, either natural or man-made, can be tools to reduce cold stress through wind, moisture and mud. Cattle will voluntarily seek out protection from inclement weather, and this protection will decrease energy needs. If installing shade structures for heat mitigation, consider if these can also be convertible to wind breaks during winter. Cleaning facilities and making sure cattle have a dry area to rest will help with comfort and reduce disease transmission. 
• Water – Even in cold weather, providing clean, fresh and unfrozen water is important for thermoregulation. When water is restricted, feed intake will be reduced, and thermoregulation will be more difficult. Water requirements in colder months are a minimum of one gallon per 100 pounds of body weight.  
• Feed adjustments – Feed and energy will need to match both performance requirements and maintenance requirements when the temperature drops. As a rule of thumb, for every degree the temperature is below the LCT, a cow’s energy needs increase by 1 percent (Dewell et al. 2021). Pregnant animals, lactating cows/heifers, stocker calves or finished cattle all have specific energy requirements that depend on their environment. Work with your veterinarian, nutritionist or beef extension specialist to ensure your foods supply is providing the energy your cattle need and adequate body condition scores are maintained.  
• Feeding schedules – Just as with hot weather, changing the feeding times can be used in cold weather to the animal’s advantage. Feeding cows in the late afternoon can help them get through cold overnight temperatures with heat production from rumination.  
• Bedding – Providing bedding in severe conditions puts a barrier between the cattle and the frozen ground, so less energy is spent keeping warm. It can also aid with reducing lameness from the frozen ground and protecting testicles on breeding bulls from frostbite. Cleaning and fresh bedding schedules should be adapted to minimize mud buildup.  
• Transport – In addition to adjusting feed and energy rations to match increased maintenance requirements, keeping animals dry in the trailer will minimize cold stress during transport. This could include protecting cattle from moisture and mud buildup prior to transport or providing bedding in the trailer during extreme conditions.  

Whether the temperature is rising or falling, cattle must maintain normal body temperature to sustain essential physiological processes. Cattle producers have long incorporated creative and effective ways to ensure welfare of their livestock in any season. For guidelines on how weather stress contributes to total quality management, check out the BQA Manual and other resources at BQA.ORG.    

Resources for further information:  

Dewell 2019. Prepare for Heat Stress Possibilities. HTTPS://WWW.EXTENSION.IASTATE.EDU/NEWS/PREPARE-HEAT-STRESS-POSSIBILITIES (Accessed September 10, 2021).  

Dewell et al. 2021. Caring for Cow Herds During Cold Weather. https://store.extension.iastate.edu/product/16101.pdf (Accessed September 10, 2021).  

Drewnoski and Wilke 2019. Helping Cows Cope with Cold Stress. HTTPS://BEEF.UNL.EDU/BEEFWATCH/HELPING-COWS-COPE-COLD-STRESS (Accessed September 10, 2021).    

This article was originally published in the October 2021 issue of NCBA National Cattlemen newsletter.