By Dan Loy, Iowa Beef Center director
Managing stress in the winter time can improve the performance of feedlot cattle. Cattle respond to cold stress by burning more calories to maintain body temperature.
There are several ways that cattle battle combat cold temperatures. One method is through internal and external insulation. External insulation is affected by hide thickness (breed and genetics) and hair coat. The temperature at which cattle begin to use additional energy to maintain body temperature is called the lower critical temperature.
Cattle with a heavy winter coat have a lower critical temperature of about 20 degrees F. When they have a summer hair coat or the hair coat is wet, the lower critical temperature is just over 50 degrees. For each degree of cold stress below this temperature their energy needs are increased a little less than 1%. The effective temperature for cold stress is impacted by the wind speed in addition to the temperature.
Other factors that affect the lower critical temperature are the cattle’s age and body condition (internal insulation) and the heat generated by the ration fed. So how do you use this knowledge to improve cattle comfort?
Provide wind protection
Reducing the effects of wind on the animal reduces that effective temperature. This might be a windbreak fence, shelterbelt, or a shelter. If providing a windbreak, try to keep it 80% solid and 20% open. This is more effective in reducing the wind speed behind the break.
Offer appropriate shelter
If you are providing shelter, give the animals enough space (>20 square feet per head) and make sure that the building is well ventilated. Poor ventilation increases stress on the respiratory system and traps moisture in the building. That moisture accelerates heat losses.
Cattle can lose heat when lying down by direct conduction. In conditions where moisture may build up in the areas where cattle bed down, bedding can provide a layer of insulation between the animal and the ground.
By being proactive in snow removal in feedlot you can reduce the potential for muddy conditions when temperatures thaw. Mud may be more stressful than cold in Iowa feedlots because it reduces the insulation value of the hair coat and requires more energy for the animal to travel from feed to water to resting areas. Cattle have the ability to thrive in cold weather. However, to live up to those abilities requires protection from the wind which can cut through their natural insulation. Protection from excessive moisture can help maintain this insulation as well. Bedding, along with proper animal density and ventilation in shelters are management tools that can help.
These are immediate steps to improve feedlot cattle comfort. For help in making longer term investments in facilities to improve cattle comfort look for more information in a series of 10 workshops to be held across Iowa In February and March. (See the next article for information on this series.)