The Vet that I talked to at the University of Missouri at Columbia advised me not to cull. As I said, the survivors are truly resistant and the birds that you should breed for resistant chicks.Thanks again!! I really hope one day there is a vaccine.
Do you think I should keep my girls that aren’t showing any symptoms, deep clean the coop and introduce new vaccinated chicks when they’re old enough? Or should I cull my 2 remaining girls and start over?
In my article I talked about my experience hatching chicks from eggs that I bought from an Amish farm about two miles from our farm and the chicks being resistant to Marek's Disease. I still have hens and some of the bantam crossed roosters from those hatchings and they are at least 7 years old at this point. I suspect that area local birds have built up a natural resistance to whatever Marke's disease is floating around.
I also brought in vaccinated bantams that are doing very well and working on their 4th generation.
What I would suggest looking into are adding genetically resistant birds to your flock. I went with Egyptian Fayoumis and currently have 6 hens and 3 roosters. I had the first birds that I bought from Murray McMurray hatchery vaccinated. I've lost a couple, one to parasite load and one to possible botulism but they are in their second generation now and doing well otherwise.
I think there are White Leghorns that are resistant along with Naked Necked Turkens. There are folks who will disagree with me but since you have active Marek's I would recommend that whatever birds you add to your flock you definitely have them vaccinated. You may still lose one or two but you will increase your survival rate. I read that Marek's will last in your soil for 7 years so it's going to be around for awhile and given the high transmission rate and it's occurrence rate you can count on it being around pretty much forever. Practice good coop management, parasite control and good diet with your flock.
Most of all, don't give up.