I live in Michigan and it is really cold but my 21 hens are laying 19 -21 eggs a day. I give them 22% protein feed and daily treats since their yard is covered in snow and the ground is frozen solid. They are young (first year). I expected them to drop production during the winter but they didn't. I also give them oyster shell in a separate container. They have access to feed and oyster shell 24/7. They absolutely love sunflower meats I get at the feed store.