Mother had coryza or MG now showed up with babies

[B2B family farm]

Hello,
I don't know what to do. One of my chickens that showed signs of either coryza or MG this past winter disappeared and came today with tiny baby chicks. We closed the flock and are about to cull everyone in about a month. What do I do with the babies? If I take them away today, is it too late? Do I also have to cull them? They look 2 days old.

 

[junebuggena]

Depends. Coryza can be cured with appropriate treatment. If it's been several months since infection, there is little risk of the chicks being sick. MG is antibiotic resistant, lifelong, and can be transferred via the egg to chicks. If it's MG, all birds will need to be culled.