As fall harvest progresses and the days get shorter, we know cold stress is just around the corner. Special attention should be given to the most delicate group of animals on the dairy: newborn calves.
The thermal-neutral zone for a calf under 3 weeks of age is 55 to 78 degrees. Within this range, the calf doesn’t have to expend extra energy to maintain body temperature. With lower temperatures, the calf experiences cold stress, needs more energy to stay warm and may not grow as efficiently as possible. Cold weather can be tough on calves, but simple management and feeding strategies can make winter go more smoothly.
Calves are born with only 3%-4% body fat. They are also born with a special layer of fat called brown fat. Brown fat’s only purpose is to release energy as heat. Combatting cold stress – and keeping the calf from using all that fat within a few hours of birth – starts in the maternity area.
Towel-drying a newborn calf helps fluff its hair coat, which insulates the calf by creating a boundary between the body and the chilly ambient air. Dry the ears as this will help reduce the risk of frost damage. Warming boxes (which need to be kept clean) work well to finish the drying process and keep calves warm during the first 12 hours after birth. Calves that receive 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 lowers.
Move dry calves into a clean, dry space with an adequate amount of bedding that ensures good nesting, such as straw. Bedding should be deep and fluffy, allowing the calf to nest and conserve energy. Bedding condition should be monitored to make sure it stays dry.
Calf jackets also limit heat loss, but calves need to be dry before they’re fitted with jackets. A jacket on a wet calf holds the moisture and chills the calf. Jackets should be clean and in good condition. The general recommendation is to have enough jackets to cover all calves younger than 3 weeks, but this may differ depending on calf housing. A good rule of thumb is to keep the jacket on the calf until it consumes starter regularly. Don’t forget to adjust the straps as the calf grows.
Close attention needs to be paid to winter ventilation. Keeping barns or hutches warm is not typically the goal. A minimum of four to six air exchanges per hour should keep air fresh to minimize disease while not allowing a draft on calves. Positive pressure tubes can help achieve this goal.
As the temperature decreases, a calf’s caloric demand increases, which leaves fewer calories available for growth and immune function. 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 daily feedings will also increase milk intake. Supplemental fat can be added to the milk feeding. Each of these options comes with pros and cons to evaluate with a calf management team and nutritionist. Pick the strategy that works the best on your farm.
No matter which option you choose, consistency is the key to success. Monitor milk mixing and delivery temperatures at the beginning and end of the feeding to minimize variation. Milk temperature at feeding should be around 105 degrees.
Throughout the year, encourage starter grain intake by keeping it fresh and dry. In addition to providing supplemental calories, starter grain intake has a secondary benefit. Heat from microbial fermentation in the rumen will also contribute to the calf’s energy needs during cold stress.
Water intake is crucial to starter grain intake regardless of the temperature. Even though feeding water can be challenging in the winter, it is extremely important. A common practice in the winter is to feed warm water shortly after milk and dump the pails before they freeze. Warm water and starter consumption are positively correlated. The more starter the calf eats, the more water it will drink.
Calf performance doesn’t need to drop as temperatures decrease. Ensure calves have adequate nutrition to support both maintenance needs and growth. Make sure drafts and wet bedding do not increase their maintenance needs. 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, continue to grow at target rates and thrive.
    Barry Visser is a nutritionist for Vita Plus.