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Dominant White Gene

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Mike Gilbert:
Poultry color genetics is not simple.  With either form it will depend on what other genes are present with the white.
Leghorns are dominant white, I don\'t think black leakage is a problem with the strains I have seen.  But supplementary genes like barring ( B ), blue (Bl), sex linked silver (S), columbian (Co) and perhaps others along with dominant or recessive white will help to make a cleaner white.   If leghorn blood has been introduced into Ameraucanas  it would definitely change the gene pool.  I\'m not sure that is a good thing.  By the way, chickens can be BOTH dominant and recessive white, the two are not allelic.

Guest:

--- Quote ---Steve, could you find info on the chicken calculator? I couldn\'t.
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I\'m sure I\'ve run it on the calculator, though not with lav added, and believe dominate, recessive, and a mix of both just called white are there. Yes, a bird could be white and either split or pure for lav under it. The trouble here are people interpreting \"100% unicolor white\" in reference to a cross of pure dominate white on black to mean the birds are visually pure white. My experience is that one copy of dominate white can and does allow black to leak a bit, and red a whole lot more.


--- Quote ---Leghorns are dominant white, I don\'t think black leakage is a problem with the strains I have seen.
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In my short experience, two copies of dominate white makes a very white bird; though I\'m not sure if the faint striping I observed in my CX\'s wing and tail feathers is a result of bleed through two copies. [It does fade back out for the most part]
I think there may be some confusion about whether certain birds are pure for dominate white, or visually white but carrying only one copy for it.
 

--- Quote ---By the way, chickens can be BOTH dominant and recessive white, the two are not allelic.
--- End quote ---


Yes, judging by the chicks produced, an Ameraucana roo used in a project was both.

Guest:
BTW; my crosses of a white Ameraucana over CX were hatched yellow and some with yellow or green shanks, and so far all feathered pure white with shanks changing to slate. Nobody well mistake them for Ameraucanas though; they\'re twice as large.  :p

Mike Gilbert:

--- Quote from: Muggsmagee ---There is a debate of sorts going on.  One side says that Dominant White is leaky and black will leak through in spots.  If Dominant covers black, can black leak through?  Or would that be merely a recessive White bird someone THINKS is Dominant White?
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Few genes are totally dominant in the impure state.  If only one copy for muffs and beard is present, they will usually be smaller than if the bird had two copies.  I think the same principle can be applied to dominant white.  With only one copy it is likely dark feathers can be present.  

John:
http://web.archive.org/web/20060316085352/marsa_sellers.tripod.com/geneticspages/page3.html

--- Quote ---Dominant white I Incompletely dominant. Influences eye pigment. Inhibits black pigment, eumalanin. This gene is ‘leaky’ and will allow black specks through. Generally not as efficient at producing a solid white bird as are two copies of recessive white. Heterozygotes of dominant white, I/i+ are often grey with the grey color visible in the chick down. Dominant white dilutes, but does not eliminate, epidermal melanin.
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http://web.archive.org/web/20060316085322/marsa_sellers.tripod.com/geneticspages/page2.html

--- Quote ---As an elementary exercise, let’s ‘build’ a white chicken.  We can start with wild-type background, e+, and require our bird to have two copies of this gene.  We can suppress the red in the chicken by adding the silver gene, S, which has the effect of changing red to white.  Black is suppressed (changed to white) by the dominant white gene, I, however this gene is ‘leaky’ (see the table for comments) and allows black specks through.  A good ‘helper’ gene in this situation is the Columbian gene, Co, since it is a restrictor of black.  Although this set of genes is not the only set that will yield a white chicken, it is one of the ways a white chicken can be obtained.
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