I've borrowed a couple lines from the links I provided earlier ...
That's breed in the first column, autosoumal genes in the second, and sex-linked genes in the third.
Barred Plymouth Rock
E/E, Co/Co, w/w
K, S, B, Id
With polygenes for red ear lobe and brown eggshell color. The slow feathering gene, K, is believed to aid in obtaining a cleaner barring. Barred Rocks have yellow shanks because of the dermal melanin inhibiting property of Cuckoo barring. Without this, the breed would have near black shanks with yellow soles.
New Hampshire
eWh/eWh, Co/Co, Mh/Mh, w/w
s+, Id
With polygenes for red ear lobe and brown eggshell color. A primary difference between New Hampshire and Rhode Island Red is the wheaten allele at the E locus in the New Hamps.
Delaware
eb/eb, Co/Co, w/w
B, S, Id
With polygenes for red ear lobe and brown eggshell color. Delawares have Barred Rock and New Hampshire genetics.
The info on the individual genes, all the genes listed above for both parent breeds ...
The E-locus alleles E Often called 'extended black', 'nigrum' or 'self black'. Extends black, changes red to black, red inhibitor.
Columbian Co Incompletely dominant.Confines black to hackle and tail in both sexes (called Columbian restriction). Thought to cause a gradient in color from head to tail. Modifies Wheaten to Buff Columbian. Has no effect on extended black, E.
Skin Color w Yellow skin color. Recessive.
Feathering Rate Genes
K
Late feathering gene
Silver and Red-Gold S This gene is called 'silver'. Inhibits red pigment, pheomelanin. The expression of silver is sometimes affected by hormonal levels and is considered to be incompletely dominant and highly influenced by modifying genes.
Sex-linked barring B Barring, cuckoo barring. Dominant. Causes white barring pattern in red and black, sometimes used as a black inhibitor, most notably in Leghorns. Cuckoo barring is also an inhibitor of tissue pigmentation and is responsible for the yellow shanks of Barred Rocks. Shanks of females can be darker. Barring shows a distinct dosage effect. B/B gives wider bars than heterozygotes have. Incorporation of the slow feathering gene results in a cleaner, more sharply defined barring.
Foot Color Id Light foot color. Dominant. Inhibits dermal melanin. Reported to have little influence on shank/foot color in birds with dark shanks due to E/E
The E-locus alleles eWh Dominant wheaten. Female body varies from light salmon to wheat color, some black may be present. Males are wild-type.
Mahogany Mh Dominant. Mahogany restricts eumelanin and enhances the color of red. Rhode Island Red is a good example. Restricts black in the back and wing of both males and females. Down color seems to be unaffected by mahogany.
Silver and Red-Gold s+ This gene is sometimes called 'gold'. Wild-type, recessive. Invokes red pigment.
Genes common to both the parent breeds: Co/Co; w/w; and Id/Id.
So ... maybe the Co/Co (Columbian) isn't causing so much trouble for us as we (I) imagine. Maybe it is the "S" silver not balancing out the "s+" gold. Or the E (Extended Black) not changing the red to black. Or the "B" (Barring) vs. the
eWh
/
eWh
(Dominant Wheaten)...? It seems the barring genes are quite complex, and partially sex-linked. But then the S gene is "incompletely dominant."
I go completely numb when I start looking at genetics, but to my untrained eye it seems a lot can go wrong with Delawares from the knees up. Even if we start with "pure" birds. Kinda makes me annoyed that people have toyed with the genetics of the Delaware to the point where some lines have even lost the proper leg color (which should be the "easy" part). For now, I've chosen to not breed birds with salmon/red/buff/brown/brassy feathers, but am trying to not freak out over "too much black." Except, of course, that certain types of black feathers in my flock are for sure destined to be paired with salmon/buff/brown/red/brassy feathers, so I take them as fair warning and set those birds aside.
Any genetics buffs care to chime in here? Please?
Source links:
http://sellers.kippenjungle.nl/page2.html and
http://sellers.kippenjungle.nl/page3.html