Some of our chickens are three years old and others could be close to five years because they were given to us by a friend. There has been a fox lurking nearby that has stolen at least 5. We have been trying to catch the fox. We have not switched where we buy our feed and we used to get 19-28 eggs a day. But could the feed be the reason they are not laying? Is protein content the most important important thing in the feed? We have not been giving them extra calcium because it is supposed to be in the feed. We get our feed at C.E. Sauder and Son in Lancaster, PA. We have about 27 chickens in the coop and it is about 10ft x 10ft. There are 6 nesting boxes and a huge fenced in yard. Thanks for all of your help!!