Winter came early this year. We can expect the rest of this season to be cold; cold and wet; cold, wet and windy. While beef cattle can tolerate winter conditions pretty well, cold stress will negatively affect animal health, welfare, performance and production.
If cows are thinner than usual going into winter, they are more susceptible to cold stress. Consider sorting cows by body condition. Smaller cows, young cows and thin cows all benefit from a higher-density ration, reduced competition and improved protection from the elements.
During cold conditions, cattle require extra energy to regulate body temperature and maintain body condition. The colder the temperature, 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 to use energy to produce heat for regulating body temperature. To survive, cattle must maintain basal metabolic function and core body temperature. If necessary, they will burn stored energy reserves to meet these needs. Thus, 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. (I use 1 percent rather than 0.7 percent because it makes the math easier.)
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 18 degrees Fahrenheit.
Alternatively, if an animal is thin or the hair coat is thin, wet or matted, the LCT could be as great as 50 to 60 degrees. 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 impact 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 for them to gain body condition.
Fall-calving cows lactating through the winter may need extra supplementation as well. These mamas often lose some body condition as they support a calf through winter, but this effect can be more dramatic when weather 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 lower dry matter intake.
Additionally, there is a relationship between water intake and dry matter intake. If water freezes or becomes inaccessible, cattle are not only at risk of dehydration, but lower water intake may cause a secondary decrease in dry matter intake. Cattle need adequate dry matter intake to help with regulating body temperature and maintaining body condition.
Beyond feeding additional energy, it is important to think about cattle comfort. To mitigate cold stress and improve cattle comfort, consider providing windbreaks to reduce the wind chill effect. Bedding also provides a layer of insulation between the cold ground and the animal’s body, similar to the sleeping pad issued to me when I was in the U.S. Army. It wasn’t a cushion but served as insulation, so the sleeping bag didn’t freeze to the ground.
Shelter can protect animals from precipitation, helping them to stay dry and improving the insulation properties of the hair coat. Pay attention to the footing for cattle. High-traffic, muddy areas that freeze create rough terrain to traverse. Mud, ice and deep snow are difficult to navigate, and cattle dislike slippery surfaces. Try to improve these surfaces.
Proper nutrition will go a long way toward mitigating the negative effects of cold stress. Evaluate your winter feed supply in terms of quantity and quality. Test forages for nutrient content. The forage test results provide significant help in developing winter rations. Visit with your local MFA or AGChoice livestock specialists to ensure your herd has everything they need to weather the winter.