Redhen what you have to understand is that a complete sterile environment for any cell or living thing is a death warrant when exposed to the outside. This is what wiped out the ancient Mayans. This is what almost wiped out some of my ancestors here when the white man brought disease they had never been exposed to. If you plan on a sterile flock then by all means keep them sterile and do not buy from Ideal.
Because Ideal flock is not MG clean does NOT mean it is MG infected, remember OJ? In your daily life you are exposed to many organisms and your body's immune system adapts and gets stronger. It helps it fight off disease, and as some of us get older we do not get colds or the flu. I have not been sick in 5 years, but I am not healthy either I have had 2 heart attacks. So I can not say I am disease free. And just because I am virus free does not mean I would not kill a person by my presence if they lived a sterile life. More then likely they would die in days.
What Ideal is saying, and I spent over an hour in conversation with them, is this. They raise healthy happy birds they do not stuff them in battery cages, they treat them as you or I would, and because of that they are exposed to elements in the environment including MG from wild birds who fly over their cages. And the point they are trying to make is that a bird that has never been exposed to disease(MG) and does or does not have it will probably suffer severe reaction when they are exposed and they will be. This is much like the explanation for the swine flu virus being so strong with young healthy instead of us old and frail. We have what is called a viral load, which helps protect us from most viral disease unfortunately it does nothing for old age.
