You may be interested in reading this article on "red suffusion lovebirds" which may be quite similar to african greys (both are african birds!)
http://www.africanlovebirdsociety.com/genetics/red.htm
Some sites with red african greys
http://www.wingscc.com/aps/g-red.htm (read the info at bottom)
http://www.animal-world.com/encyclo/fea ... cruffy.php (Red factor grey which is probably due to feather plucking)
http://www.wingsnwhiskers.com/timnehgrey.htm (timneh)
http://www.tcaviary.com/chickpages/cagc.htm (bottom of page)
In short, red factor could indeed be due to deficiencies in diet as chicks, but I think there are other reasons to the suffusion as well.















