Most baby dairy calves are extremely vulnerable to the threat of disease in the late fall or in early winter, as any arctic chill magnifies the shortcomings of a feeding program and living conditions. To avoid a disaster, these milk-fed calves need to be placed on a higher plane of energy nutrition and assured a comfortable housing.
Nobody is advocating an entire revamp of their diets or building a new calf barn. In most cases, it simply means having a look at the calves outside and making some improvements that go a long way in reducing calf cold stress.
Initially, it comes down to meeting a dramatic increase in dietary energy requirements of calves from newborn to weaning, which is mainly temperature dependent during the winter. Once the temperature of an outside hutch or a protected calf barn falls below 60 F (15 C), calves may start to burn extra dietary energy just to maintain their core body temperature, which is key to survival.
Research on dairy calves housed in laboratory thermal units has demonstrated for every drop of the thermometer by 1 F below 50 F (10 C), a calf requires one per cent more energy (excluding other environmental factors such as wind chill and wet weather). At home, it means dairy calves overwintered in an outside hutches on a brisk winter day of 0 F (-18 C) require at least 50 per cent more dietary energy compared to their counterparts raised in an insulated heated calf barn.
When dietary energy is inadequate, it’s quite predictable that cold-stressed, outside dairy calves struggle. Poorly fed calves not only divert available feed energy meant for growth and health to keep warm, but they will almost immediately break down limited fat reserves. In extreme cases as body fats are exhausted, calves will start to irreversibly break down muscle and tissue proteins, and thus starve to death.
Most winter nutrition situations are not that extreme. There are many simple things that dairy producers can implement to improve the winter nutritional status of their pre-weaned calves:
- Feed whole milk or high-fat (20-25 per cent) all-milk calf milk replacer. The University of Illinois (1989) increased the fat content of whole milk and milk replacer diets fed to outside pre-weaned dairy calves. As a result, fat-supplemented calves gained more than 50 per cent compared to energy control-fed calves.
A common milk-feeding rule of thumb for overwintered dairy calves is to increase the amount of milk or milk replacer fed by two per cent for every 1 C degree, the temperature drops below 10 C (re: one per cent for every 1 F degree below 50 F). This advice means if five litres of whole milk or milk replacer are routinely fed to each calf and the temperature drops from 10 C to 0 C (re: five litres x two per cent x 10 degrees drop = +1.0 litre), then a total of six litres of milk or milk replacer should be put in front of each calf.
- Increase the concentration of milk replacer fed to outside calves. Increase the amount of milk powder mixed with warm water; from a regular 13 per cent solution (130 g per litre) to 15-16 per cent solution (150-160 g per litre). Feed 2.5-3.0 litres of reconstituted milk replacer to each calf (depending on age), twice daily.
- Implement a third feed daily. To avoid the possibly of osmotic scours due to increased milk replacer concentrations, feed an extra 2.0 litres of regularly mixed up milk replacer (12-13 per cent solution). An extra feeding of whole milk can be fed in the same manner.
Calf starter should also be introduced to outside dairy calves just as those calves fed at any other time of the year. Two-week old calves won’t eat a significant amount of calf starter to receive much dietary energy, but they will nibble on it. In contrast, when they become five to six weeks old, one calf should consume to a kilo of calf starter per day and then can be weaned.
- Another helpful hint for feeding dairy calves during the winter is to provide at least two to three litres of extra fresh water per animal fed separately from the water that they already receive by whole milk or milk replacer feedings. This free water is necessary, particularly for older calves, to help meet their natural requirement for water and to encourage more dry calf starter feed intake. It is important that this free water be clean, fresh and if fed outside, not frozen in the pails.
Be warm and dry
These suggestions put winter dairy calves on a good plane of nutrition, but it should also be complimented with equally good winter-housing conditions. It’s a matter of making sure that calves are kept clean, dry and warm.
All calves should be housed with a thick pad of bedding such as clean straw (dirty wet bedding removed), which insulates them from the cold ground or concrete floor. Furthermore, dairy producers should keep all dairy calves out of drafts in the calf barn or direct winds blowing upon their outdoor housing. Any factor that causes a major loss of heat in dairy calves only adds to their need for more dietary energy in their feeding program.
A dairy calf should never struggle to keep warm during a cold winter, because they simply will not grow and will become more susceptible to disease. As soon as the first northern breezes blows across the farmyard, it’s a good time to review pre-weaned calf feeding programs and insure extra dietary energy is being fed. An energy boost to the diet or attention to good housing goes a long way in helping pre-weaned calves achieve all their energy requirements that not only helps them survive a cold winter, but optimizes good performance. †