alot of people on here already use these, or variations on these. They work best with meat birds, but CAN be used with any bird, not that they SHOULD. If you modify them to fit nest boxes, more shelter and have a lower stocking density they can actually work really well for layers in most parts of the country during the spring summer and early fall. I'v even talked to Show bird breeders who used them to mature large numbers of birds before they culled out the non SQ ones. Joel Salatin is a great farmer and i greatly admire his work, however people seem to be using his ideas as a base way too much, instead of branching out and experimenting for themselves, but as of yet, the tractor is most likely the best way to pasture broilers, in general, depending on the circumstances.