Gwen, I think you are taking my post wrong. What I mean is you keep weak chickens, and you weaken your whole flock. As far as CRD goes, all chickens carry it, but the weak ones are the ones that typically that show symptoms. (I am talking adults mostly here.) When you get one showing symptoms, then it tends to want to spread through your flock. I am NOT trying to tell anyone what to do, or that their way is wrong for them, just trying to explain a proven method to improving the over all health of your entire flock so you don't have as many genetic issues, or consistently have health problems to deal with. Also, not trying to disrespect anyone, but I raise hundreds of birds on my yard every year, so keeping them healthy is very important to me, because I don't have the time to spend with each individual bird. Also, it also makes a difference for me to do this because I raise them to sell, and want to sell only top quality birds, and won't sell anything less. Thanks.