The hair on cows' udders need to be kept short. Short hair is easier to keep clean and dry.
Long hair is difficult to clean and dry and wet teats are often milked.
Many herds are finding it easier and faster to burn the hair on the udder rather than clip. Using a propane torch to singe the hair off is quick and painless. When done correctly, burning the teats and udder doesn't occur. We have done it four years in our herd. Rub loose sawdust, dirt, and manure off the udder.