I need all your help and advise. My layer pen is an older flock, so when 1 became weak and died it wasn't much of a surprise. Then another and now 1 more is behaving odd. All three birds have gone down with in a week and a half. The only symptoms seem to be lethargy and weakness. They spend about a day sitting in one place, standing with tail tucked, then become to weak to walk before dying. If taken to the drinkers and feeders they will eat and drink. They don't feel like there is any weight loss. One bird here and there is understandable, but one rooster and two hens in such a short space of time is weird. I've not seen any odd poo's, eggs are still being laid, they are on 16percent layer pellets. Can you think of anything else to check for??? Thanks in advance!