In the past few weeks I‘ve continued to put more layers on as I prepare to go out to the barn on these colder days. As we head through the end of fall and go into the winter months don’t forget to put in place some extra layers of protection for your calves in order to prevent cold stress. A calf’s thermoneutral zone is between 50-68ºF, which means that heat produced by the calf is equal to the amount of heat lost. Below 50ºF the calves need to have extra energy in order to maintain body temperature or else they will use their limited body reserves to meet maintenance requirements. A rule of thumb for energy needs is for every 1º decrease from 50ºF a 1% increase in energy is required. The protein body reserves that a calf will tap into if it isn’t given enough energy are not good sources to keep the calf warm or for supplying the calf with the proper immune response. The lower critical temperature (below 50˚F) is influenced by wind, humidity, hair coat (dry vs. wet), sunlight, bedding, rumination, age and size.
The top issues when addressing cold stress in calves are nutrition and housing related. Below are some facts and tips to implement to keep your calves growing and lively this winter.
When calves need additional energy to maintain maintenance requirements, where do they get it from?
1. Higher amounts of milk or milk replacer (MR)
- To get the added volume of milk or MR a third feeding might be needed.
- Warm milk or MR to 105˚F so that the calves do not have to warm it back up to body temperature. When mixing MR according to the directions on the tag for temperature make sure that the MR has time to reach 105ºF by the time it reaches the calf, but not below.
2. Increased fat intake
- Many feed companies have “Winter Blends” which have higher protein and fat concentrations especially for the youngest calves who are only on MR and will need the additional energy for maintenance.
3. Increased starter intake
- The sooner calves start eating starter the faster they will be able to gain excess heat from fermentation. Research done by Nonnecke et al. found that calves that were cold stressed ate more than the calves who were not cold stressed because their maintenance requirements were greater.
- Offer lukewarm water (63-82˚F) 2-3 times daily as this will encourage starter intake.
What can we do to make sure the additional energy we give our dairy calves won’t be wasted when it comes to housing management?
1. Bedding: Calves lay down for more than 18 hours a day, so make sure their bedding is deep, clean and dry!
- If the bedding is deep enough the calf’s feet should not be able to be seen when they are laying down.
- Bedding materials should be free of soil, mold and pathogens. Chopping or blowing bedding in the calf area can be cause for concern when it comes to respiratory disease.
- When calves are on wet bedding there can be a 60% greater heat loss then if that bedding was dry. There are two ways to check and see if the bedding that is going under your calves is dry or not. A) Koster test a sample of your bedding, if it takes less than 15 minutes for you to get a consecutive reading of similar weights the bedding is dry, if the weight of the bedding continues to drop as it stays on the Koster tester longer the bedding is wet. B) The second option is to kneel in the bedding under the calves if you feel your pants getting damp after 15-20 seconds the bedding is too wet.
- Using adequate straw as bedding can allow calves to nest and create a stable air pocket free from drafts.
2. Ventilation is all about dilution!
- The goal when ventilating a barn is to take the outside air and distribute it evenly throughout and move the polluted air outside.
- Hutches must allow for steady air movement and solar heating while providing protection from winds and drafts.
3. Blankets if dry and clean can help insulate calves below 3 weeks of age.
Overall, there are two main things that should be addressed when preventing cold stress in dairy calves:
1. make sure the calves have adequate nutrition to support their maintenance needs and allows them to grow and
2. Be sure the housing they are in is not increasing their maintenance needs with drafts and wet bedding. Keep your calves growing and healthy! Stay warm!
* References: Broadwater, Neil. Caring for calves in cold climatic conditions. University of Minnesota Extension. 2010.
Leadley, Sam. Bedding Calves for Cold Weather. Calving Ease. February 2011.
Nonnecke, B. J., M. R. Foote, B. L. Miller, M. Fowler, T. E. Johnson, and R. L. Horst. Effects of chronic environmental cold on growth, health, and select metabolic and immunologic
responses of preruminant calves. 2009. Journal of Dairy Science. 92:6134-6143.
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