Timing for this column is a bit delayed as the days are getting longer and we’ve recently seen a few days above freezing; however, we know it’s been a cold winter in the Midwest, and we still have cold days in front of us. A significant amount of information focuses on the benefits of heat abatement as we reach the upper critical temperature-humidity index around 68 degrees F. Little research, however, focuses on cold stress in dairy cattle.
    Mature dairy cattle produce an incredible amount of heat through rumination and the digestion of feedstuffs, and thus withstand weather conditions that we might find unbearable. While most cows in the Midwest are sheltered, experts have suggested the lower critical temperatures at which cows might eventually sacrifice milk production may fall between freezing and zero degrees F. At this threshold, cows begin to expend extra energy to maintain body temperature. This is dependent on many variables, including air movement in a barn, humidity, extent of winter hair coat, production level, and bedding type and condition.
    Dry matter intake (DMI) can often be a limiting factor on production for lactating dairy cows. While cows have a mild capacity to increase energy intake through extremely cold weather, there are limitations. Forage quality and rate of digestion will impact rumen fill. Work with your nutritionist to adjust DMI and energy density during extremely cold weather. Feed bunk management practices, such as feeding frequency, feed pushup and distribution, are more critical than ever during cold months. In addition, we deal with frozen chunks of silage and other moist feeds in the TMR, and feeds are consumed at a temperature much cooler than the standard environment of rumen microbes.
    Water consumption is critical to maintain DMI even in cooler temperatures. While winter water consumption is lower than summer, high-producing dairy cows still benefit from a minimum of 2 linear inches of available water space. In addition to frozen water, ice buildup can limit water access. Techniques with salt or sand can reduce this challenge, but take advantage of breaks in the cold to remove this ice and accelerate the process. Cleaning waterers in the winter months can also be a challenge. Again, take advantage of warmer periods to focus on this task.
    The primary challenges with prolonged cold stress often go beyond nutrition. Frozen, chunky bedding results in compromised lying surfaces and impacts stall usage. Extra effort should be made to keep stalls filled, groomed, clean and dry. Frozen manure in alleys and slippery floors can be a concern for cow movement and injury. Footbath usage often decreases (for obvious reasons) during periods of cold weather, resulting in increased lameness. Teat health can be compromised. Drying and dipping strategies are often adjusted to reduce the risk for mastitis.
    Consideration needs to be taken as we enter the next few months of transitioning weather patterns. A quick removal of the long, winter hair across the topline of incoming heifers and sometimes dry cows is beneficial to a smooth facility transition. Monitor air quality in the barns. Often, we have walls or doors buttoned up tight in the dead of winter and may need to reevaluate with warmer daytime temperatures. Fan and sprinkler maintenance will also follow in the next couple months. Despite what the groundhog might indicate, winter will come to an end soon.
    Barry Visser is a nutritionist for Vita Plus.