Why is a green or purple sheen in black feathers an issue?

Yes, Red Junglefowl are accepted by the American Bantam Society as a breed (between the Japanese Bantam and the LaFleche entries as "Junglefowl"). I quoted the from the Bantam Standard for their official color description. Purple (violet) is prefered in Junglefowl according to that standard.

The Redcap bantam is inactive in the Bantam Standard, but remains an accepted, active breed (both large fowl and bantam) in the American Poultry Association's Standard of Perfection, which is what I referenced. I think it really needs a little help/interest.

Inactive breeds are those that are either extirpated from the US or there is too little interest in showing them. Aseel bantams are listed as inactive in the 2006 edition Bantam Standard, but were "revived" for the 2011 edition. There are about 3 dozen breeds on the inactive list for the ABA.

Poultriary said:

OK, I have been reading [quick apology, I was not a good researcher and didn't write down my resource] and apparently the purple sheen in chickens is an indication the bird did not have enough protein in its diet, or had something else going on that inhibited proper feather development. I will have to go back and find thhe reference again, unless someone else can confirm this.

Click to expand...

Waking up and old thread here, as I am trying to figure out how i can fix my Svart and FBCM chicks, I already give 20% protein starter and add in 25% calf manna multi species supplement. Is it possible I need more still?

glacierridge said:

Waking up and old thread here, as I am trying to figure out how i can fix my Svart and FBCM chicks, I already give 20% protein starter and add in 25% calf manna multi species supplement. Is it possible I need more still?

Click to expand...

There's a bunch of info on the Net about this. try keyword searching.: purple "green feathers" : Oh I wish I could remember it offhand.
Best,
Karen
Ah, I think here is help for you in one of my fav pithy poultry books. The author had 40 years breeding fancy poultry when he wrote it. Had a knack for making complex things simple. Was a renowned poultry judge and creator of the White Laced Red Cornish breed. I so like this little book. It is about Laws, not opines ad theories.
LAWS GOVERNING THE BREEDING OF STANDARD FOWLS
---------
A BOOK COVERING OUTBREEDING INBREEDING AND LINEBREEDING
OF ALL RECOGNIZED BREEDS OF DOMESTIC FOWLS, WITH CHART
By Card, Wetherell Henry.
https://babel.hathitrust.org/cgi/pt?id=chi.087299559;view=1up;seq=5
excerpt from:
CHAPTER II Black or White and Black and White Breeds
Pages 27 and 28.
"To the average fancier black fowls may seem to have the same shade of black; yet to the pains- taking, observant breeder of black fowls there appears a color aura overcasting each black breed, superinduced by the color of skin, legs and feet. For instance, the sheen of the plumage of a black breed with yellow skin, willow legs and yellow bottoms to feet is noticeably different in its over- casting aura from the sheen of a black breed with black or blackish legs, white or flesh colored bot- toms to feet and with white skin. On the yellow skin fowl this many times is apparent in a bronzed appearance of what should be the greenish sheen. This is more tangible to the average fancier than the color aura before mentioned. The bronzing is related to the yellow skin and not necessarily to the objectionable purple barring. Purple bar- ring bears the same relation to black fowls that brassiness does to white fowls and its permanency can be traced to the same cause, namely, short breeding and infusions of foreign blood, and not always lack of care or ill health. Nature always asserts itself in surface indications on black fowls wherever there is trouble internally. In such cases the plumage takes on a brown dingy cast throughout. Sometimes it only appears in plumage under wing and in under-color of fluff. Such a bird should be discarded as a breeder. The brown tinge sometimes seen in summer just before and during moult should not be confounded with the above ; search for this trouble in mid-winter or just before the breeding season. One proof that in and line breeding will eradicate the evil of purple barring is found in that old Chinese breed, the Black Langshan. I have handled many hundreds of them in the last ten years. Their remarkable freedom from purple barring in any and all strains, under any and all conditions, and the persistent disfiguring purple barring so prevalent on newer breeds of black fowls lead me to these positive conclusions. The bronze over- cast before mentioned, if found on a white-skin black fowl, indicates an infusion of yellow skin blood and a careful survey of the bird in question will show traces of yellow in skin and legs or bottoms of feet. White or gray feathers in flights or tails of black breeds are not so much indications of foreign blood as they are of imperfect moult, injury or lack of vitality. Lack of shade, negligence or ill health contribute to accentuate purple barring or sheen but never produce it to any great extent on black fowls of long pedigree. Red feathers found in black birds are not signs of impurity in any and all black breeds ; for instance, the Black Sumatra, one of the very purest of black breeds and a very old one, produces many birds with red feathers in black plumage. The chicks of most black breeds at hatch are black and white in about equal proportion, which colors they retain until feathered."
I highly recommend the whole book, it's a good'un!
Best Success,
Karen