Ok, I'll say this again. NO one has to cull their birds if they'd rather treat and treat and treat. These rules are what I do, me, myself. I repeat, these are the rules I follow to keep my own flock healthy. Did anyone read #10? It's your responsibility to do the research. I've done mine. This is the way I manage my own flock and it has served me well from the start. I dont want a bunch of birds with weak immune systems. I dont want to always be treating some disease that, by nature, will never go away. So, if someone else does, that's their decision....till and unless it impacts someone else's flock.