Kenya Mwangi
Songster
Hello Do you think @JacinLarkwell can still keep chickens? Or not a good idea?I suspect a percentage of birds within a flock have genetically inspired resistance against it that is reenforced when they become the breeders in the flock. Natural selection, in other words, sorts it out. Natural selection has been removed from the equation in hatcheries where many generations of birds have likely never been exposed. Hatcheries are breeding birds that would have been weeded out of the gene pool 150 years ago on the farm.
I have produced Marek’s resistant birds from parents that died from it, but sometimes it takes literally 100 chicks to make 1 that doesn’t seem affected by it from a rooster that was prone to it. While breeding chickens that seem immune as tested by time makes lots of chicks that appear to be immune (or resistant or whatever the appropriate term is for being asymptomatic long-term).