The thermal neutral zone
A newborn calf’s thermal neutral zone is between 60 and 77 degrees Fahrenheit. The thermal neutral zone is the temperature at which an animal is the most comfortable and extra energy is not required to maintain normal body temperature.
When environmental temperatures are below the thermal neutral zone, the calf uses energy just to maintain its body temperature. Even on a warm winter day of 40 degrees Fahrenheit, the maintenance requirement for calves younger than three weeks old is 40 percent higher than when temperatures are within the thermal neutral zone. At zero degrees, the maintenance requirement is about double.
Additional measures must be taken during the winter to help calves stay warm, healthy and continue to grow in the cold.
How to help calves stay warm and healthy in winter
Calves must be born in a very clean, dry environment
Calves are born with only three to four percent 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. To prevent using all the fat within a few hours of birth, dry off calves rapidly.
The calving area should also be draft free. Warming boxes or rooms should be considered if calving in outside cold facilities. Four quarts of colostrum should be fed as soon as possible after birth to provide passive immunity and nutrients to the newborn calf.
In cold weather, calves need more energy just to maintain body temperature. This is particularly important during the first three weeks after birth, before calves consume much calf starter. Once calves consume starter and begin to ruminate, heat produced by feed digestion helps keep calves warm.
Unless calves are already consuming eight or more quarts of high quality milk replacer or whole milk per day, consider increasing the amount of milk offered up to these levels or higher.
- Research shows this will not result in scours and the extra energy will allow calves to better fight off disease.
- Increase the number of feedings per day from two to three or increase the amount of liquid at each feeding.
- Do not just increase the amount of milk replace powder in the same amount of water. This has the potential to cause dehydration, especially if water access is limited.
- Feed milk at 105 degrees Fahrenheit.
- Milk can cool rapidly during extreme cold.
- Adjust the initial temperature to achieve a milk feeding temperature of 105 degrees.
Wearing blankets in cold weather helps keep calves warm.
Canadian research shows that when calves were housed at a temperature of zero to -22 degrees Fahrenheit, blankets provided a 52% increase in whole animal insulation.
- Offer calves warm water daily. This can be a challenge in our winter climate.
- Drinking water stimulates consumption of grain that promotes rumen development.
- Consider offering warm water after calves are finished with their milk.
- After 10 minutes, empty the water from the pails before it freezes.
- Another option is to offer warm water other times during the day.
Clean, dry bedding
- Provide lots of clean, dry bedding. Calves’ hair coats provide excellent insulation if they are clean and dry.
- Kneel in the bedding. If your knee gets wet, the calf will also get damp when lying down.
- Deep bedding allows a calf to nest down in it and provide a barrier of warm air around itself.
- Bed calves to a nesting score of three, where the calf is able to nestle deeply into the bedding material, and its legs are not visible.
- Most hutches have openings or vents to keep air fresh for the calves.
- If no air is circulated within the facility, there is an increased disease risk because heat and moisture can create an environment that is open to pathogen growth.
- Well-designed air tubes keep small amounts of fresh air distributed throughout the building without creating a draft.
Delay weaning during extremely cold weather. Holstein calves can normally be weaned when consuming 1.5 to 2.0 pounds of starter for three consecutive days. However, since weaning is a stressful period, delaying weaning during extremely cold weather is recommended.c
Source : umn.edu