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- #1,991
I understand those points for sure. But, you still have dead unvaccinated birds and living vaccinated birds.
this shedding issue only applies to the MOST virulent strains of Mareks. I’m not trying to say whether someone should or should not vaccinate, but rather what the vaccine does or doesn’t do.
IF you have a very virulent strain, chicks are dead immediately before the virus can replicate and spread. Vaccinated birds are able to live and shed this virulent strain into their environment. In this situation a virulent strain can live on where it *may* have not with quick deaths to those affected.
IF you have one of the more common forms, non vaccinated birds will not succumb until they are also shedding the virus. In this scenario non vaccinated birds help to spread the virus through your flock at a greater rate than they do with a virulent strain. However the vaccination is shown to reduce the shedding potential of an infected bird with on of the less virulent strains.
I have yet to see a single study on breeding resistant birds which is why I’m personally skeptical it’s possible in backyard or breeder flocks. I have seen multiple studies that say they think they have identified a potential gene for mareks immunity but no way to isolate that for breeding.