Quote: You can opt to just do the new flock, and this is another reason to have separate areas, feed, and water. If you do not have to do the others, you will still have eggs from them. When you are done, you can scalp the area that they were wormed in, and let the sun dry and bleach it for you to get rid of any remaining parasite eggs in the lawn. We do free ranging in large fenced yards. New birds go in tractors, or kennels. There is not much you can do about air born on a small lot, but you can for parasites, external/internal, and fluids from eyes/sinus, biologicals passed on your body, or boots. We always take care of the newly hatched first, and the new to the yard last (even if from a hatchery). Sorry if everyone is freaking you out, but most of us have had a brush with some kind of invasion or other.
I'll share my most recent. Gape-Worms! had to worm and treat close to 20 birds, and new what the problem was, but could not find the active ingredient to treat. The vet asked me to weigh them all in this group to give him an idea of weight for meds, but he was taking to long to get back to me. After all the on-line research, it came down to asking the right person about that ingredient, and yes, Beth new what goat med had it in it, and at what dose to administer. I gave it right away to the young pullet in distress, and in the drinking water of the rest of her flock (because of the way it is passed). By the time the vet was able to get back with me, we could already see improvement in her, and after the flock was done, I did another group that was not laying because one of the birds was with them (fence hopping Bantam) also, and I still have never had to do my main run, or the other two that run against it. Doing these three runs would have meant no eggs for not just us, but everyone that gets eggs from us. They can be wormed in the winter, when egg production is not stuck in the on position. All the ones I did worm, are laying now, and have even put on weight. This was not something that I even brought in from outside, it comes from them grazing, and scratching, and the worm-er for chicken at TSC does not work on it (different active ingredient). If I had not known what I was looking at, I would have lost lots of birds from this.