As I listen to seasonal music, I can’t help but wonder how the dairy calves and cows are weathering the cold.

When the temperature drops below an animal’s lower critical temperature (i.e., the point at which animals are no longer in the zone of thermal-neutrality), it needs additional energy to stay warm. Figure 1 shows the average low temperatures during the winter in the U.S.

Young calves

The lower critical temperature for a calf is 59°F. Below this temperature the maintenance requirements of calves increase. Since most states in the U.S. reach below 59°F, most calves can benefit from additional energy in the winter months. In addition, calves are born with less than 5 percent body fat; this makes it even more difficult for these animals to sustain themselves in cold climates.

There are a few nutritional options that can be implemented to keep calves growing during the cold weather.

1. Feed more milk or milk replacer to get the necessary energy into calves. Commonly, this is accomplished by either adding more volume per feeding or adding a third feeding mid-day. However, this option leads to the overfeeding of protein, which can be expensive.

2. Feed a high fat/winter blend milk replacer. Although preferred over the previous option (as protein is not being over-fed), it is typically fed throughout the winter regardless of temperature and energy needs.

3. Add a supplemental fat to the liquid milk replacer. This is the recommended option because it can be fed as needed, depending on seasonal temperature and weight of the calf. These fats are soluble in warm water and available from most milk replacer companies.

In addition to providing calves more energy, calf feeders should feed warm water at each feeding and encourage calf starter intake, as ruminating calves are easier to keep warm.

Also consider using calf blankets on newborn calves, appropriate use of windbreaks, and providing adequate clean, loose, deep and dry bedding. Calves will flourish during the winter months when given the opportunity.

Cows

Cows handle the cold weather much better than calves. Their lower critical temperature is 32°F. When the temperature drops below the lower critical temperature, the maintenance requirements of the cows also increase. Table 1 shows the increasing energy needs as the temperature drops and how the temperature affects the overall maintenance energy. Surprisingly, even though these changes are not as dramatic in an adult animal, in most cases, nutritionists do not alter feeding programs during the winter weather.

However, this year is not like past years. Cows are not carrying additional adipose tissue reserves. The dairy industry has had a rough year, and most producers fed less-expensive rations to get through the tough times. This has left many cows with lower body condition scores. Cows in the upper Midwest lost body condition in the winter months due to cold stress last winter, but they had the body condition to lose. This year, they don’t have that extra layer of fat to utilize.

My recommendations are (1) monitor the temperature where the cows are housed and body condition score on the cows at least every two weeks and (2) adjust the ration energy density as needed. Thin cows are harder to breed back and have a greater likelihood of being anovular. Reduced reproductive efficiency is costly, so producers should do what they can to prevent the problems before they occur.

Bottom line
Give your dairy calves and cows the additional energy they need to get through the winter months. The result will be calves that continue to grow and can fight off immune challenges better and cows that continue to produce milk and breed back more efficiently. PD

• Robin R. Rastani

• Nutritionist
• MSC Specialty Nutrition
• Email Robin R. Rastani