Take some of the stress out of cold stress

Although beef cattle can tolerate extreme winter conditions surprisingly well, cold stress can negatively affect animal health, welfare, performance and production.

Christopher Clark

South-Central Iowa Extension Beef Specialist / Iowa Beef Center / Iowa State University

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During cold conditions, cattle may require extra energy to regulate body temperature and maintain body condition. The colder the temperatures, the more nutrition the animals will need. The thermoneutral zone is the temperature range in which animals do not have to expend energy to maintain body temperature.

The lower critical temperature (LCT) is the lower limit of the thermoneutral zone. Temperatures below the LCT require animals use energy to produce heat for regulation of body temperature. In order to survive, cattle must maintain basal metabolic function and maintain core body temperature.

If necessary, they will burn stored energy reserves to meet these needs. Thus, in order to maintain body condition, cattle must receive enough daily energy to maintain body temperature in addition to the energy required to meet maintenance requirements. For each degree of cold stress below the LCT, cattle require approximately 0.7 percent more energy just to maintain body condition.

The LCT is variable and depends on numerous factors such as hide thickness, coat thickness, wind speed, moisture, etc. The LCT for an animal in good body condition with a heavy, dry winter coat could be as low as 18ºF.

Alternatively, if an animal is thin, or the hair coat is thin, wet or matted, the LCT could be as great as 50ºF to 60ºF. When estimating cold stress, try to think in terms of effective temperature or wind chill. In other words, how cold does it feel? Wind exposure can have a dramatic effect on effective temperature and LCT.

Keep a particularly close eye on thin cows and lactating females. Thin cows lack the insulation of fat cover and could benefit greatly from windbreaks and protection from precipitation. They may also need greater energy supplementation as compared to cows in adequate body condition.

For each degree of cold stress below the LCT, thin cows may require as much as 1.5 to 2 percent more energy to maintain body condition. Even more than that will be necessary in order for them to gain body condition.

Fall-calving cows lactating through the winter may need extra supplementation as well. Fall-calving cows often lose some body condition as they support a calf through winter, but this effect can be more dramatic when winter conditions are severe.

Dry matter intake is usually greater during cold stress. Keep in mind, however, that severe cold stress, especially in combination with mud, ice, extreme wind, etc., may lead to lesser dry matter intake. Additionally, there is a relationship between water intake and dry matter intake.

If waters freeze or become inaccessible, cattle are not only at risk of dehydration, but lesser water intake may cause a secondary decrease in dry matter intake. Reduced dry matter intake would certainly not help with regulation of body temperature and maintenance of body condition.

Other considerations

Beyond feeding additional energy, it is important to think about cattle comfort. There are many common-sense things that can be done to mitigate cold stress and improve cattle comfort during the winter. Windbreaks can reduce exposure to the wind, thus elevating the effective temperature experienced by cattle. Bedding can provide a layer of insulation between the cold ground and the animal’s body.

Shelter can protect animals from precipitation, thus allowing them to stay dry and improving the insulation properties of the hair coat. Pay attention to footing – high-traffic, muddy areas that freeze create rough terrain for cattle to walk on. Mud and deep snow can be difficult to navigate – and ice, of course, can be slippery.

Do what you can to improve these surfaces and use low-stress cattle handling as much as possible when working cattle.

In areas affected by drought this growing season, it may be even more challenging to support cattle through cold-stress events. Some cattle may be thinner than usual going into winter, making them more susceptible to cold stress. Consider sorting cows by body condition.

Thin cows can benefit greatly from a higher-quality ration and lesser competition. Thin cows could also benefit from extra shelter. A simple windbreak or a roof to keep them dry can make a big impact on animal comfort as well as on health and productivity.

Additionally, evaluate your winter feed supply in terms of quantity and quality. Consider sampling forages and submitting for nutritional analysis. Forage testing is relatively simple and inexpensive. The results can offer great guidance as you prepare winter rations.

Drought conditions often force producers to use CRP hay, road ditch hay, cornstalk residue and other low-quality forages. When supplemented appropriately, these forages can be utilized successfully but, without supplementation, may not be adequate to support females through winter weather.

Do not be afraid to ask for help. Nutritionists, extension specialists, veterinarians and other advisers can help you interpret forage testing results, formulate rations, compare supplements, etc. Watch for educational programs, extension meetings, webinars and other educational forums that may offer some guidance.

Try to think ahead as much as possible so you are ready when the first snow flies. Evaluate your cows’ body condition scores now and adjust your feeding program appropriately to achieve adequate body condition scores before winter arrives.

Evaluate forage supplies early to allow plenty of time to source additional forage and supplements, if necessary. Consider all your options for supplementation, thinking about how compatible feedstuffs are with forage-based diets and about price per unit of energy and price per unit of protein.

Plan ahead to offer windbreaks, shelter and bedding. Think about winter feeding areas so you know how and where you will feed. With some planning and attention to detail, you can take some of the stress out of cold stress this winter.