By Travis Meteer
With winter weather and cold temperatures setting in, it is time to talk about when cows feel the cold. The big factors that determine the lower critical temperature for cattle are temperature, wind speed, and heaviness of winter hair coat.
Colder temperatures, higher wind speeds, and lighter hair coats will increase maintenance requirements. With a good winter coat, cattle will perform normally until temperatures drop below freezing (32°F), assuming no wind. If cattle have a heavy winter hair coat they can withstand temperatures as low as 19°F, again with no wind. When temperatures drop farther or wind chill is factored in, energy requirements increase approximately 1% for each degree. An easy way to get a ballpark figure on wind chill is to take the temperature and subtract the wind speed. So if it is 5°F with a wind speed of 10 mph, then the wind chill index is close to -5°F.
Rain followed by cold temperatures can cause a lot of cold stress. Wet hair coats provide virtually no protection from wind and cold. This results in onset of cold stress at much higher temperatures. A hair coat that is wet have a lower critical temperature of only 59°F.
If facilities are not available for cows to escape the rain, wind and cold temperatures, cows use more energy to help cope with the cold. Cows in good BCS can mobilize body reserves to meet the energy demands of short-term cold stress.
Source : illinois.edu