We have 10 hens and a rooster. They mostly go ranging during the day and get shut in the coop at night. However, there is an 7 X 4 ft run covered in heavy duty 1" squared metal chicken wire. The run is a little over a year old and so it has no grass and has been packed down hard. Does a run ever get old - go bad - or become toxic to the birds? Is it okay that every morning they walk around on packed dirt and feces? We clean the coop out a lot - but not the run. My DH fenced it all in with no door . Thanks.