IMG_0299In the upper Midwest, winter is a fact of life.  It is common to see severe cold temperatures, dangerous wind chills and snow.  Good winter management practices contribute to healthy and productive cattle, reasonable feed costs and humane care.

Beef Cattle adapt to colder temperatures during gradual changes in the season by growing longer hair, changing their metabolism and hormone secretion, and depositing insulating subcutaneous fat if the energy level in the ration allows.

Beef cattle increase body heat production as a response to severe cold by increasing their metabolic rate, and as a result they need more energy and nutrients during cold weather to meet maintenance requirements.

Just exactly when does a cow begin to feel cold stress?  The point of cold stress, or lower critical temperature, depends in large part on the amount of insulation provided by the hair coat.  As shown in Table 1, the insulation value changes depending on the thickness of the hair coat and whether it is dry or wet.

Table 1. Lower Critical Temperature for Beef Cattle

Coat Condition Critical Temperature (degrees F)
Wet or Summer coat 59
Dry Fall Coat 45
Dry Winter Coat 32
Dry Heavy Winter Coat 18

The Lower Critical Temperature is the temperature at which maintenance requirements increase to the point where animal performance is affected negatively. A general rule is that for every degree that the effective temperature is below the lower critical temperature, the cow’s energy needs increase by 1 percent.  For instance if the effective temperature is 17 degrees F.,  the energy needs of a cow with a dry winter coat are about 15% higher than they would be under more moderate conditions.   That energy requirement jumps up to about 40% higher under those conditions if the hair coat is completely wet or matted down with mud.

There are some management considerations that we need to keep in mind regarding changes in feed intake in response to cold stress and the cow’s need for more energy.

  • Make sure that water is available.  If water available is restricted, feed intake will be reduced.
  • If the feed availability is limited either by snow cover or access to hay feeders, the cattle may not have the opportunity to eat as much as their appetite would dictate.
  • The ration has to be of the quality level that the cow is able to eat enough to meet nutritional needs.
  • Be careful providing larger amounts of high concentrate feeds.  Rapid diet changes could cause significant digestive upsets.

A clean dry open hair coat and protection from the wind are very important factors that help cattle tolerate cold temperatures.

Wind and/or moisture makes the effective temperature (the temperature felt by the body) lower than the temperature on the thermometer. Wind chill must be included when calculating the amount of degrees below a cow’s critical temperature point. For example, a 10 mile per hour wind at 20° F has the same effect as a temperature of 9° F with no wind. If the temperature drops to 0° F (or equivalent of zero, with wind chill) energy requirement of a cow increases between 20 to 30% – about one percent for each degree of coldness below her critical temperature.

Mud can also reduce the insulating ability of the hair coat. The relationship between mud and its effect on energy requirements is not as well defined, but depending upon the depth of the mud and how much matting of the hair coat it causes, energy requirements could increase 7 -30% over dry conditions. In addition, there is research that suggesting mud may also be associated with decreased feed intake.

Using adequate bedding to keep the cattle dry and clean in addition to providing them with shelter from the wind and a place to be dry will help the cattle cope with the adverse weather.  Make sure whatever shelter you have is correctly ventilated to minimize the risk of respiratory problems from bad air quality.

It’s important to remember that cattle can adapt to short term weather changes relatively well without a significant impact on performance.  A cow can deal with a few cold, miserable days without suffering long-term effects.  However, ignoring the energy costs of long-term cold stress greatly increases the risk of problems down the road during calving and subsequent re-breeding performance.  Any steps that we can take to lower the cold stress the cows have to contend with, such as providing wind and weather protection, help reduce her maintenance requirements.

Source: Bill Halfman UW Extension Agriculture Agent