This past weekend, during the Minnesota youth deer hunting season, I found myself sitting in a deer stand with my three daughters pondering a few thoughts. First, a lesson in patience. Any parents who have taken their kids hunting can appreciate this. In addition, Saturday morning brought measurable snowfall in northwest Minnesota followed by a plummet in temperatures. I could not help but think about the cold stress on dairy calves in the months ahead.  
    In sub-freezing temperatures, calves (and all mammals) are motivated to maintain internal body temperature. Thermal stress can increase calf morbidity and mortality and reduce growth rates. Focusing on the increased needs of calves in the winter months can provide the best opportunity for success.
    – Maternity and newborn calf housing. Combatting cold stress in calves starts in the calving pens. Calves are born with minimal body fat reserves. In addition, the calf’s small body mass relative to external surface area results in rapid loss of body heat. Clean, deep-bedded straw helps, but wet calves lose heat quickly to the environment.
    Towel drying a newborn calf aids in fluffing its hair coat, which works as an insulator for the calf by creating a boundary between the body and the chilly ambient air. Pay attention to drying the ears as this will help reduce the risk of frost damage. Warming boxes work well to finish the drying process and keep calves warm during the first 12 hours after birth. It is important to note that calves receiving supportive warming therapy after birth will have less stress and, as a result, will likely have greater efficiency of immunoglobulin absorption from colostrum feeding. A calf’s ability to absorb antibodies from colostrum diminishes as its body temperature becomes colder.
    Calves should be moved out of the warming box by 24 hours of age and into the next calf facility. It is best practice to sanitize these warming boxes between calves as their warmer temperatures provide a good environment for pathogen growth. Once calves are moved, deep-bedded straw is a great option for its insulating effects. Calves placed into hutches and cold barns should be furnished with calf jackets for approximately the first 3 weeks of age.
    – Nutritional considerations. The first goal for calf nutrition is to satisfy maintenance requirements. Increasing the plane of nutrition to combat cold stress is of primary importance. Caloric demand for maintenance increases as the temperature decreases below 60 degrees Fahrenheit. This leaves the calf with few calories available for growth and more susceptible to mobilizing body fat reserves and amino acids. Additionally, energy is pulled away from the immune system, making calves more prone to diseases.
    Strategies to increase energy intake during cold stress include altering the amounts and timing of milk feeding. Milk volume is often increased by about one-third. Shifting from two to three times daily feeding will also increase milk intake. Supplemental fat can also be added to the milk feeding. Work with your calf nutritionist and advisors to decide which strategies fit your operation best.
    Water intake is critical to starter consumption and rumen development. Offer warm water to calves after the milk feeding. Pails may need to be dumped prior to the next feeding in extreme cold conditions.
    – Additional management considerations. Excessive calf handling should be avoided during really cold days. Consider holding off on pen moves or vaccinations if possible. Another consequence of cold weather is greater fluctuation in milk feeding temperatures. The ideal feeding temperature is about 105 degrees Fahrenheit. Precautions may need to be taken to prevent a significant decline.
    As we enter winter, make sure the calves have adequate nutrition to support both maintenance needs and growth. Make sure their housing conditions do not increase maintenance needs with drafts and wet bedding. Monitor and track calf growth and health. This will help identify bottlenecks and troubleshoot challenges. Excellent management during winter will allow calves to overcome cold stress and continue to grow at target rates.
    Barry Visser is a nutritionist for Vita Plus.