I am raising my first flock of chickens. I have 9 hens, 9 months old, who range in the backyard all day and sleep in a coop in the garage at night. I have noticed that one of my Ameraucanas (4 Ameraucanas, 5 sex-links) is wheezing a little and occasionally making a "moaning" noise that makes me think of my own asthma. I haven't noticed this in any other chicken, but it seems they have all been a little unenthusiastic about eating sometimes. I think all of them are laying.
Boulder County Colorado poultry
It sounds like a respiratory issue. If it is only one chicken, you may want to separate the hen to prevent anything from spreading. Check the dust levels in the house. If more chickens get sick, you have a respiratory disease of some sort. It is hard to diagnose since the symptoms are the same for most respiratory diseases. Check with your local diagnostic lab if it appears you have a disease situation.