About a month ago, I bought chicks from a customer of mine, who had hatched them from another silkie breeder. They'd also bought a pullet that quickly became sick. Vet tested the pullet, and she had MG. They put the pullet down, but the vet told her that now she had to worry about the eggs. After the chicks hatched and reached 6 weeks of age, the vet tested one-third of the 25 of them. They were clear. I've kept the eight I bought after testing and quarantined them anyway. We made them a place where they'll stay quarantined all winter, as I'm still very cautious.MG can be transmitted through hatching eggs, where one or both parents are carriers. It is always a risk bring in chicks from another breeder or hatching eggs. Testing is the only way to know if they have a disease. There are as many as 8 different respiratory diseases, but infectious bronchitis virus, mycoplasma (MG,) and coryza are common ones. Environmental things such as mold, poor air circulation, and fumes from soiled and wet bedding are common problems with chicks.
If these now three-week-old chicks are still sick at six weeks, I'd recommend getting them tested before mixing any of them with your other chickens.
