Most of the discussion of calf feeding and management in cold weather revolves around these questions; Should I start feeding more milk? Should I increase total solids? Should I add a fat supplement during the winter? A goal of these feeding strategies is to provide more calories to the calf.
Beyond cold stress, calves face a lot of other challenges in winter. For this reason any discussion of winter calf management cannot be solely focused on what you’re feeding, but also on the calf’s housing environment. We should be more concerned with how we can help the calf conserve body heat rather than just supplying them with more energy to burn. Priorities for calf housing in winter aren’t all that different from what our goals are year round, they just become essential to allowing the calf to perform well under cold stress. Whatever the housing system, our goals are to keep calves dry and to control air movement to provide enough ventilation but remain draft-free at the level of the calf. For calves housed in heated barns or rooms, ventilation becomes our main concern and providing additional nutrients becomes even less critical.
We’ve conducted a number of trials to better understand what the calf really needs in winter. The goal of these trials was to evaluate bedding materials (straw or dry wood shavings) and various milk replacer feeding rates. Trials comparing the two bedding types with a total of 1.0, 1.25 or 1.5 lb of a 20% protein 20% fat milk replacer fed daily, showed the following for optimal feed and bedding practices with calves weaned at 42 days:
- Calves grew better pre-weaning as more powder was fed. However post-weaning growth was just the opposite. By 12 weeks of age calf body weight was greatest for calves that were fed 1.0 lb of milk replacer powder.
- Calves that were fed 1.0 lb of milk replace consumed more starter on average which lead to better gains in their post-weaning period.
- For calves fed 1.5 lbs of powder, calf body weights and overall growth rates were better at 12 weeks.
- Data found that the biggest impact on calf performance was bedding material. Straw bedding was shown to have a greater impact on overall performance over bedding of wood shavings, and even better than feeding more milk.
- Other studies report significantly less respiratory sickness when deep straw bedding is provided vs. shallow straw or wood shavings.
To optimize calf growth and performance, calves need an optimum dietary protein to energy ratio. When feeding >1.5 lb solids, calves achieve the best performance when fed a 24 to 26% protein and 17% fat milk replacer, as compared to feeding 1.5 lb of a 20 to 22% protein and 20% fat milk replacer. Feeding too much fat reduces frame growth and increases fat deposition. While fat is a fast energy source and can be quickly metabolized for body heat production, it is more important to feed a well-balanced diet. Adding more fat to a calf’s diet further reduces starter intake which leads to less rumen development and poorer growth post-weaning.
When calves are fed more than 1.5 lb of solids they have little desire to consume starter. If you choose to feed more than 1.5 lb of solids from either milk or MR, this should only be done for the first 3 weeks of a calf’s life. During this time the calf does not normally consume much starter anyway. After 3 weeks of age, we do want to cross that threshold of 1.5 lb of solids. This provides the calf with plenty of nutrition but also keeps the calf curious which will encourage early starter intake and good rumen development. The heat of fermentation of dry feeds in the rumen will also provide warmth to the calf.
The best way to keep a calf warm and dry in the cold weather is to bed with deep straw. Hutches need to have straw added prior to, and immediately after, rain or blowing snow to insure the calf has a dry place to lay. We should be doing everything possible to minimize the amount of time they have to lay on wet bedding. Wet or muddy patches in a heifer’s hair coat significantly impairs her ability to conserve body 
heat. If a calf is kept dry and provided enough straw to achieve a nesting score of 3, they are able to stay warm even as temperatures continue to drop at night. Notice how in Figure 1, calves that were bedded with deep straw are able to steadily increase their body temperature in the evening. This is accomplished by nesting, which traps the air warmed by the calf body, effectively making an air blanket.
The above article was contributed by Xavier Suarez, Provimi.
Cold Weather Calf Management Key Points:
- Manage housing to ensure calves are dry in a draft free, yet well ventilated environment.
- Deep straw bedding is the gold standard for bedding in winter.
- Most programs should increase intakes to 1.5 lbs of solids from milk or milk replacer per calf, per day during the winter. You can choose to feed up to 2 lbs. of solids, but intakes should be reduced at 2 weeks of age to encourage starter intake. Increased consumption of dry feed allows the rumen to develop and sets the calf up for good post-weaning growth.
- Calf jackets aren’t always practical but can be an effective solution on some farms. Jackets should only be worn for the first three weeks of life and should always be washed between calves.
Helpful Article References:
University of Wisconsin Extension: Winter Feeding Calves
Iowa State University Extension: Cold Weather Calf Care
Penn State University Extension: Calf Management Tips For Cold Weather