yes,Dirt Farmer, you are correct. BUT the key here is "commercial flocks".... as in those large factory farms with flocks of hundreds, or sometimes over a thousand birds per building. But if you are talking about small sustainable farms raising heritage breeds of poultry then the finding of these "studies" do not apply.
We raise only heritage breeds here on our farm, and they do better on pasture than in confinement. We raise them all natural & in smaller numbers than tose commercial operations, and they are moved to large pens & allowed out on the pasture starting at age of 5-7 weeks old.
We do vaccinate for Mareks & LT as those are 2 diseases common to our area.
As for predator control we use 6 ft. high fencing around their whole pasture & have 2 livestock guardian dogs, a Great Pyrenees & a Belgium Malinois. .As long as the chickens stay INSIDE the fence line they are safe.
Birds that habitually fly over the fences?? I usually start naming them "fox bait."...... LOL
Just as there is more than one way to skin cats, there is more than one way to raise poultry. It all comes down to what breeds & method works best for you & of course what the intended purpose for your flock...... personally, the welfare of my chickens is my main concern. I have used just about every system there is and this is what works best for me.... pasture raised, grass fed chickens are happier & healtiher chickens, in my book....
