A number of factors must be considered when moving dairy heifers or beef cattle inside for the winter after being outside for part or all of the summer season. The type of housing needed will depend on the enterprise and purpose of the animal. Most farms have facilities or systems in place. Cattle may even stay out or need minimal shelter, except when calving in cold weather. Trees may not be enough. A three-sided shelter open to the south may suffice.
The ideal housing provides protection from harsh weather, is sufficiently ventilated, but not drafty, is bedded and dry, and allows animals to choose their comfort level, if possible. Ideal housing is also designed to prevent respiratory disease. Animals should not be coughing. Lung damage in calves and heifers, even when treated and seemingly cured, will negatively affect performance later. Most cattle are comfortable around 50 degrees F. Cattle in good condition with a good winter hair coat will be comfortable at lower temperatures. This will help to avoid cold stress, but could also cause heat stress in a closed or poorly ventilated environment.
A loafing barn open on one side should allow for 50 to100 square feet of space per animal depending on their size. The bedding pack could be sloped toward the opening to allow animals to lie in one direction and facilitate the flow of floor moisture outward. Such buildings are typically 30-40 feet deep. Allow sufficient headspace for air flow and bedded-pack accumulation. Avoid over-stocking. Be sure to group animals by weight or size to avoid competition for feed or space. Provide adequate water. Avoid slippery or muddy surfaces around waterers.
Keep in mind that the same building may also serve as shade in the summer. Therefore, a vented side(s) and roof peak opening are also important. Natural ventilation will depend on orientation, elevation, prevailing winds and distance from surrounding buildings or trees. Natural ventilation is inconsistent and will often need to be supplemented with mechanical ventilation, certainly in an enclosed structure. Maintain fans and other ventilation systems. Check belts and remove dirt and debris.
Nutrition needs to be adjusted to provide additional energy. According to the National Research Council, the critical lower temperature for cows is between 0 and 20 degrees F. The critical temperature, however, depends on the animal's general health, age, body condition or fat layer, acclimatization, pregnancy, wind chill, wetness, length of exposure and other factors. Be vigilant in extreme weather because animals may actually eat less since they hesitate to go outside to eat.
North Dakota State researchers found that cows will need one additional pound of TDN for each five degrees below their critical temperature, or 1% additional TDN for each degree below their critical temperature. Animals that consume 2.5% of their body weight as hay for maintenance in mild conditions could need 3.5% of their body weight for severe cold. This would translate into an additional five pounds of hay or three pounds of grain per day for a 1,000-pound animal.
Researchers at Kansas State University developed a wind chill index for cattle. 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 or wind chill equivalent drops to zero, the energy requirement of a cow increases between 20% and 30% or about 1% for each degree of coldness below her critical temperature.
Wiegand is the Extension agriculture agent for Burnett, Washburn and Sawyer counties.