The yellow color leaves the outer ring of the scales, then leaves the
entire scale, on the front of the shanks first, and finally leaves, after
a longer and greater production, from the scales on the rear of the
shanks. The scales on the heel of the shank—that part of the
shank just below the back of the hock joint—are the last to bleach
out, and for this reason may generally be used as an index as to the
natural depth of the original yellow color of the various parts of
the bird. A bleached-out shank on an average-sized bird with an
average yellow color indicates that the bird has been laying fairly
heavily for at least from 15 to 20 weeks.
