Some may not like this, but here is my take. I enjoy my chickens. I take care of them, they are probably spoiled to some degrees, as they have a great hen house and my flock of 14 hens free range on 1/2 acre. But, and here it is. They are livestock and that should be kept in mind. I have added birds to my flock a couple of times, without any sort of quarantine. I place them in the hen house with the flock at night, so they wake up together the next morning and then let them sort it out. I only intervene if the well being of one of the birds is in jeopardy. Chickens, like people need to be exposed to certain things to strengthen their immune system. Now saying that, I will not take, or purchase a chicken that looks to be anything less than, a healthy, productive chicken. I would not take an old chicken, or a chicken that looks or acts unhealthy. I will finish by saying, this is my opinion and my approach. However I have never lost a bird handling it this way. Again, they are livestock. If they appear to be healthy and you can verify they are productive, then take them.