By Sam Leadley
Newborn calves may require their own version of a receiving blanket, used to protect babies from cold and drafts. The difference is they’re called calf blankets. Made of insulating-type fabrics such as wool, polyester blends and insulating foams, calf blankets fasten in place with straps, Velcro and/ or ties. The obvious reason to use calf blankets is to keep calves warm in cold weather. But what’s cold to a newborn calf? There’s a temperature range, called thermoneutral, where the amount of body heat produced by a calf is balanced by body heat losses. For an 85-pound newborn calf, this range is about 50 – 78 degrees, assuming she’s dry and in a draft-free environment. As temperatures fall below 50 for an extended period, a calf has to burn extra energy to maintain her body core temperature.
How heat escapes
No matter what the weather, heat can escape from a calf in four ways:
1. Evaporation. Heat from her body is used to evaporate water primarily on her skin and hair coat. This loss is easy to solve at birth. After dams lick off their calves, finish the drying and fluff up her coat. If calf housing during the first month of life doesn’t provide a dry place that protects a calf from rain and snow, a water repellant blanket can keep her drier.
2. Conduction. Most calves less than a week old spend 90% of their time lying down. Is the bedding dry or wet? Direct contact with wet straw results in three times as much heat loss (conduction) as contact with dry wood shavings. A moisture repellant blanket can slow down conduction heat losses through damp bedding.
3. Radiation. This occurs when heat is transferred through the air from a warm object – the calf – to a cold one – concrete or snow. Radiation losses are reduced if calves can lie down some distance away from the cold object. A blanket provides an insulating barrier to reduce heat moving away from the calf’s body.
4. Convection. These losses occur when air passes over the calf’s body. Draft-free housing where a calf can snuggle down into a bed of straw minimizes convection losses. But when bedding doesn’t allow any hollowed out nest and the pen is wide open for air movement, as in most greenhouse-like structures or pole barns, convection losses can be higher. A blanket can minimize heat loss by radiation that is subsequently carried away by convection.
How do blankets fit in?
There are three prime situations where calf blankets can fit into your calf management program:
1. The smaller the calf the greater the potential for her to lose body heat because her ratio of surface-to-body mass is much greater than for even a 130 –pound heifer. These small calves may be the youngest ones or have had especially low birth weights. I always bed these little girls with an extra flake or two of straw. But rather than just depending upon extra bedding, blankets can be used.
2. Calves housed where there’s a lot of air move- ment or where they can’t find a draft-free spot can benefit from calf blankets – especially very small and young calves.
3. The greater the difference between the calf’s body temperature and the air around her, the more potential for her to benefit from a calf blanket. In very cold weather, North Dakota State University researchers found that calves with blankets gained 1.4 pounds daily from birth to four weeks compared to a 1.2-pound gain without blankets.
- Put blankets on dry calves rather than wet ones. Aim for a “fluff-dry” hair coat to take maximum advantage of blankets.
- Use dry, clean blankets; they’ll provide better insulation. Aim for bedding that keeps blankets relatively clean and dry. Producers who use blankets prefer machine washable ones.
- Blankets are most cost effective for short term use. With a limited number of blankets, use them on smaller and younger calves in cold weather.
The above article appeared in the September 2001 issue of Northeast DairyBusiness magazine
and further supports the use of calf blankets in raising healthy calves.
It is used with permission of Northeast DairyBusiness magazine,
6437 Collamer Rd., E. Syracuse, NY 13057. (800) 334-1904.