A friend had to get rid of his five one-year-old hens. In the past, we've only added hatchlings to our flock, so we are starting these new birds in a separate coop. I understand 30 days is the standard quarantine period, and we are getting close to that point. None of the new birds is showing any obvious signs of disease, but I'm wondering if there are more subtle things we should be looking for. And I've also heard that even healthy birds can be carriers. So is there any way to be 100% sure the new birds are safe to integrate into the flock after their quarantine period? Thanks very much!