Look into the information about the mareks vaccine making a "super" mareks strain in your flock.
It is ineffective--likely even at one day.
Also, their immune system is immature and it often does not take. You are supposed to re vaccinate later--like at 6 weeks I think.
Do you have any links to the source of this information? I've never heard any of it before but if it's true I'd love to read more.
