IMO it is very irresponsible for you not to cull the entire flock...................... in some states it's required and if you don't they will when they find out you are keeping a MG disease ridden flock. Why do you think you can manage an incurable disease when you couldn't keep your flock free from it to begin with. This is reason this disease is reaching epidemic proportions and it started with the hatchery industry and their poor quality and poor disease managemnet in the first place. Closing your flock is not a solution to the problem, they will always be carriers even in the egg. perhaps you should do your homework before putting anymore birds at risk, whether you think it's not an option or not your flock should be culled ASAP. I am sorry for your dilema but you must do the responsible thing, if you don't just consider yourself a contributor to the growing problem.