They are fine, I mean really fine. Then all of the sudden they are crippled... This is happening to a graoud of 12 weeks olds. The first was about 6 weeks ago. Last week one just dropped dead. And this morning other wass crippled. That sounds like Mareks doesn't it??? How can I prevent it? At what age to vaccinate? O r should I? Have 40 eggs due to hatch this friday. It just makes me SICK.. Any advice will be greatly appreciated! Thank you.