I just brought home 5 new chicks, all 3 weeks old today, and they are all pretty lethargic, not energetic at all like other chicks I've had at this age. They are all laying in the brooder box which they can get warmer under the lamp and have room to move away from it if they get too warm, when they are laying down (which has been practically all day) they open their mouths to breath, and make what I can only describe as a "snoring" sound, it started with one last night and now 4 of the 5 are doing it. I do have older chickens outside who have had no contact with the younger ones, I wash and change my boots when dealing with each set of birds, as I don't want to have to cull my whole flock and have the new guys quarantined. They will randomly shake their heads and one seems to have a runny nose with a clear discharge. I will not risk my outside flock but do not want to cull if I don't have to, if I can fix this I want to, but from the research I have done it seems like this is a respiratory infection and even if I do treat and fix these birds they will always be carriers (if I've read the information correctly) which would inevitably infect my flock outside when I move them out there? Any advice would be greatly appreciated!!!!!