Cold stress in cattle can be measured by more than temperature. Several stress factors are responsible for the animal's perceived wind chill.

* Thickness of the animal's hair. Calves that have moved from southern parts of the United States to the Plains often experience more initial problems with the weather than those raised in northern states. Besides the travel stress, these calves have less hair and are more prone to illness or lost appetite.

* Age. Older cattle will show less stress than younger ones.

* Degree of fat buildup. Cattle with extra fat or those consuming large quantities of feed also will show less stress than thinner ones.

Cold-weather stress on cattle creates a need for more energy. Animals that are more sensitive to winters' cold may need an additional energy source. (See critical temperatures chart.) Maintenance requirements go up as each degree of temperature goes below what is listed.

Degrees of cold are multiplied by the percentages in the energy increase chart to calculate the percent of increase the animal needs to maintain its body temperature.

The cold facts:

  • The optimum winter temperatures for cattle with a heavy coat is 20 to 35 degrees Fahrenheit.
  • For every 15-degree drop in temperature below the comfort zone, daily gains are reduced 10 percent.
  • A 25 mile-per-hour wind has the same effect as lowering the temperature by 27 degrees.
  • Digestibility is lowered 2 percent for every degree drop.
  • Maintenance requirements rise 1 percent per degree change below the comfort zone.