“Poor quality hay may not provide adequate energy to maintain gestating cows that are entering the third trimester,” he said. “Consider having the hay tested to determine if you need to supplement during times of possible cold stress, especially for the enduring cold spells.”

He said to consider separating younger and thinner cows that may not have the same internal insulation as conditioned older cows and supplement them accordingly or offer them higher quality forage if available. Coleman said equine owners can employ similar strategies and separate animals according to body condition score.

“Producers should move cows to fields with natural windbreaks or provide man-made windbreaks, which are not the same as a barn,” Lehmkuhler suggested.

“Poorly managed barns combined with poor ventilation may actually hamper efforts to improve the environmental conditions. Lastly, remember it is energy or calories that are really needed. If the protein level in the forage is adequate, do not make supplement decisions based on protein level; rather purchase the most affordable calories. Stay warm and keep the waterers flowing.”

The lower critical temperature (LCT) value for cattle is the lowest temperature or wind chill at which no additional energy is required to maintain core body temperature.

“As the temperature declines below this lower critical value, the maintenance energy value for the animal is increased to maintain core body temperature,” he said. “Animals maintain core body temperature by increasing their metabolism resulting in greater heat production, as well as other heat conservation strategies such as reducing blood flow to the extremities, shivering and increased intake.”

Lehmkuhler said several things can influence lower critical temperature value.

“Both external and internal insulation influences the LCT. External insulation is basically the depth and thickness of the hair coat, condition of the hair coat and thickness of the hide,” he said. “Thin-hided breeds such as dairy breeds tend to have a lower insulating factor than thick-hided breeds like Herefords. The condition of the hair coat is extremely important as an external insulation barrier.”

He explained the hair coat acts as insulation similar to home attic insulation that traps air, enhancing the insulating value. If the hair is wet and full of mud, air is excluded, reducing the insulating value and increasing heat loss from the skin to the environment.

The density of the hair coat and if it is wet or dry impacts the wind chill temperatures at which cold stress is considered mild, moderate or severe. As little as 0.1 inch of rain can immediately impact cold stress severity by matting the hair down reducing its insulating ability. Acclimation time, hide thickness, fat cover and other factors will also influence the degree of cold stress that animals experience.