Kern O,
Cattle will grow a winter coat of thick curly hair to help protect them in the colder months. From what I've read & been told, a bovine does not expend extra energy to keep warm between the temperatures of 30° and 50° F. They will stay warm because of their hair coat and the heat produced by fermentation in the rumen (Definition:the first division of the stomach of a ruminant animal, in which most food collects immediately after being swallowed and from which it is later returned to the mouth as cud for thorough chewing).
We are fortunate in that our winters are mild. It is rare we have extended cold times, that being temperatures below freezing. However, a wet 40 degrees with strong winds can be taxing on the herd. This is why it is important to have a sheltered area, good quality hay and or feed, and water available. Our sheltered area is nothing more than a very thick stand of cedar trees down in a hollow. This is where I feed hay bales during the winter months. Les is also correct about the fat layer. That's why quality feed should be provided. The higher the protien in the feed the less fat reserve the bovine will need to utilize.
This is why most cows don't come knocking at your door during the winter. That's my bovine lesson for the day.
Oh, Steve, I know exactly what you mean. Mine might as well be standing up looking at their watch with a scowl on their face.
Wayne