One question I would have with the results...how much of that is simply from the fact of being in sunlight?
Caged birds typically are in artificially lighted buildings, never seeing the light of day.
A lot of the health benefit in the egg comes from simply being in natural sunlight.
I would be interested in seeing a comparison between caged (artificially lighted) and fed solely commercial feed vs. open air (sunlight) and solely fed commercial feed vs. strictly open air and foraging with no commercial feed but only bugs and plants they can find. I suspicion the results would vary vastly with the quality of range, and many of us would be very challenged to provide the necessary range with no supplemental feeding.
Just curious.
LofMc