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4 keys to keeping calves warm

Sarah Morrison for Progressive Dairyman Published on 08 January 2019
calf in straw bedding

Calves are an investment for the future. How you protect that investment could have big consequences for their future productivity.

Cost of feed is a large portion of the cost of raising replacement heifers through the pre-weaning period. During the fall and winter, that investment may increase when feeding changes are often implemented to meet the increased maintenance requirements of calves experiencing cold stress.

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Calves fewer than 3 weeks old are more likely to experience cold stress, often characterized as temperatures below 59℉. Under this threshold, to maintain body temperature, either the calf must consume more energy or the environment must be managed to minimize the increase in their maintenance requirement. Ideally, both of these strategies would be implemented. If we do not feed and manage calves properly during cold stress, the calf will be forced to use what limited body reserves it has to meet the most basic maintenance requirements (thermal regulation, immune and stress responses). Consequently, growth will be limited.

While increasing nutrients is one part of the story, other management tips can be implemented to help alleviate cold stress. Try to find a balance between what can and cannot be controlled so that the scales are tipped in the calf’s favor. Certainly we have little control over what Mother Nature throws our way, but there are several steps that calf managers can make that influence the maintenance requirement of the calf. We have greater control when it comes to what goes into the calf in terms of nutrients, but we can also work to control each calf’s environment. Ultimately, these four steps will alleviate the severity of the overall impact of environmental temperatures on calves and help them grow to their full potential.

1. Start at birth

Calves are the most susceptible to cold stress right after they are born. They are wet. They are in a cold and drafty barn. The bedding is not as dry as it could be. The cow may not clean it up fast enough. It needs warm colostrum. All of these factors quickly add up and take a toll on the vulnerable calf. While the calf’s hair does provide a warming layer of protection, it needs to be dry to be effective. Minimize the time between when a calf is born and when it is dried off. Use a clean, dry towel to help dry calves off to warm them up. Move the calf to a hot box or warm area with no drafts as soon as possible. And do not forget the timely feeding of colostrum within the first one to two hours of life.

newborn calf, wet vs. dry

2. It’s more than providing the nutrients

Regardless of the nutritional value, every liquid meal a calf gets should be at, or just above, body temperature (target 105ºF) when the calf is drinking it. Calves will expend additional energy to heat a meal to their body temperature, increasing maintenance requirements. Provide starter to calves within the first week of life. As a calf begins to consume starter, the rumen starts to ferment it and will generate internal metabolic heat, essentially creating its own space heater. Research has shown that provision of warm water over cold water during winter increases daily consumption throughout the pre-weaning period. Water should be heated to about 105ºF (the calf’s body temperature) and offered to the calf several times a day starting at birth. Water intake is directly linked to starter intake and rumen development.

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3. Bedding and calf jackets

When a calf is lying down, there is a large surface area of body contact with the ground. As a result, substantial amounts of heat can be lost if there is insufficient bedding and if the bedding is wet. Therefore, bedding should be dry, deep and well drained. Straw is the most insulating bedding to the calf and is ideal in cold weather. Body heat is retained in the air pockets of straw, which helps to reduce heat loss to the environment when the calf is lying down. When the calf is lying down, you should not see its legs. If you do not provide enough bedding to hide the calf’s legs, you may need an additional calf jacket to keep the calf warm. Insulating calf jackets can be a great addition to a calf program and used in combination with proper bedding as they allow for more body heat to be retained by the calf. Make sure you have enough jackets for your youngest calves at the highest rate of calving during the winter months. Additionally, you may need extra jackets so that you can wash them and make sure they stay clean and dry.

calf lying vs. standing

4. Ventilation

In the winter months, there needs to be adequate air turnover to minimize ammonia and other microorganism accumulation while making sure there are not any drafts directly on the calf. Walk through your calf barn and get down to calf level. If you feel a draft or smell ammonia or other foul odors, some adjustments should be made to improve ventilation and minimize cold stress. Excessive ‘fog’ in the barn or condensation on interior surfaces may also indicate improper air exchange. The changes that can be made will be dependent on the type of housing the calves are in.

Calf nutrition is only one piece of the puzzle when raising healthy and properly growing replacement heifers in winter. Factors that influence the degree of cold stress can really add up, especially when calves are literally left out in the cold. At the end of the day, how you manage those calves is your insurance policy for the investment you have made in your calf nutrition program.  end mark

Sarah Morrison is a research scientist at the William H. Miner Agricultural Research Institute.

PHOTO 1: Bedding should be dry, deep and well drained. Straw is the most insulating bedding to the calf and is ideal in cold weather. Body heat is retained in the air pockets of straw, which helps to reduce heat loss to the environment when the calf is lying down. When the calf is lying down you should not see its legs. Staff photo.

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PHOTO 2: The thermal image shows a relative scale of temperature through the different colors, with the warmest being the darkest red and the coldest shown in blue. The first thermal image is of a calf that is newly born and is still wet. More of the calf including the ears, nose and legs are colder, indicated by the green and blue. The second picture is of a calf that is also newly born but has been dried off. The colors on the dry calf show that it is warmer than the calf that is still wet.

PHOTO 3: The thermal image shows a relative scale of temperature through the different colors, with the warmest being the darkest red and the coldest shown in blue. In the first picture, the warmest parts identified is underneath the calf jacket. In the second photo, the calf stood up, and on the bedding where she had been lying down, a section of red, or warmth, still remains, highlighted by the thermal image. Photos by Sarah Morrison.

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