Don’t let the unseasonably nice weather permit you to ease up on calf care. It is still winter, and newborn calves need more than 4 quarts of milk during winter months.
Calves are very susceptible to cold stress. This is especially true for calves during the first three to four weeks of age before they consume measurable quantities of calf starter grain.
The environment has a significant impact on maintenance requirements. During the winter, calves require deep, dry bedding to help them maintain their hair coat’s insulating capabilities. A wet environment with limited bedding greatly enhances heat loss.
Calves are born with relatively low reserves of body fat that they mobilize during periods of low energy intake or environmental stress. Cold weather has a big impact on nutrient requirements for a 100-pound calf. For example:
- At 68 F, feeding 1 gallon of a milk replacer with 20 percent fat provides enough energy for about 0.5 pound of daily gain.
- When the temperature drops to 41 F, 4 quarts of milk replacer is just enough to meet their maintenance requirements with nothing left for growth.
- If the milk replacer has only 15 percent fat, 4 quarts of milk replacer is only sufficient for maintenance at 50 F.
Dairy animals are small, with thin skin and a light hair coat, so they lose body heat more quickly than larger animals. The smaller the calf, the more important this relationship becomes. Virginia Tech research revealed that small calves, such as Jerseys, have a maintenance requirement that is at least 15 percent higher than large-breed calves such as Holsteins.
The length of time between feedings can be another stressor because most calves are fed equal amounts in the morning and again later in the afternoon. As a result, calves face nutritional stress during the long evening interval between feedings when the temperature drops at night. Calf feeding rates need to be increased during the winter. A 20 percent fat milk replacer is highly recommended versus those with lower fat content.
Feeding rates should be increased by at least 50 percent or doubled under extreme cold. Feeding 1.5 gallons of a 20 percent fat milk replacer reconstituted to 12.5 percent solids provides sufficient energy for 0.23 pound of gain at 32 F. However, calves would need 2 gallons of this liquid to maintain a growth rate of 0.4 pound at 20 F. Research indicates the higher susceptibility of small calves to cold stress is why a 25 percent fat milk replacer was developed for Jersey calves.
Calf blankets also can help reduce heat loss if they are kept dry. My research at NDSU noted appreciable early growth and reduced morbidity of Holstein dairy heifers that were protected with blankets. The greatest benefit to calves was during the first month, with additional benefit up through weaning. Based on our experience and the acceptance by dairy producers who use blankets, I believe having at least a few blankets on hand is a worthwhile expenditure to keep those winter-born calves more comfortable.
Finally, feeding management must change to enable calves to grow and resist digestive and respiratory diseases. Don’t skimp on liquid feeding programs, especially during the first weeks of life when calf starter intake is low. Limiting the amount of milk or milk replacer (12.5 to 15 percent solids) to less than 1.5 gallons daily or using poor-quality milk replacer may reduce feed costs, but it can increase treatment costs substantially and possibly lead to increased mortality or reduce the animal’s lifetime performance.