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#116762 - 07/31/17 07:54 PM Clear legs on whites
Kaalnek Offline
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Registered: 07/16/02
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Loc: California
It was to my understanding the clear legs on whites were due to things like barring, mottle etc as both dominant and recessive white did not have an effect on the pigmentation in the dermal layer?

Saw a comment on double dose of dominant white clearing the legs to yellow. They were talking about a yellow leg (dominant)white outcrossed to black legged black then breeding back to double dose dominant whites to clear up the legs.. got me to wondering if my understanding was incorrect..


Edited by Kaalnek (07/31/17 07:59 PM)

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#116764 - 08/01/17 05:44 AM Re: Clear legs on whites [Re: Kaalnek]
Hen-Gen Online   content
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I share your preconception. Of course we don't know whether the dominant whites concerned also carry barring and/or mottling.
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#116765 - 08/01/17 12:43 PM Re: Clear legs on whites [Re: Hen-Gen]
Wieslaw Offline
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Well, I did not actually read any thorough studies on I and its influence on epidermal eumelanin, that takes into account the eumelanin removing factors present in yellow legged blacks(like black leghorns or wyandottes). They can be easily present in white leghorns or others. So the jury is still out on this one in my opinion.

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#116766 - 08/01/17 01:25 PM Re: Clear legs on whites [Re: Wieslaw]
Kaalnek Offline
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Registered: 07/16/02
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Loc: California
Thanks to both of you for answering.

I'd forgotten about the yellow leg blacks, that's a good point to consider. What's the most common/likely genotype for that by the way?

The discussion went like this: breeding (black leg)black to white messes up the leg color on whites. The response was it being due to single dose I, double dose I clears up the legs.

My first thought was Mo/mo+, B/b+/- were in play but then thought it was strange, no mention of barring, mottle or something else. I have done my own crosses and all of them proved to have B or B^Sd- via F2 intercross and back to blacks.

I was going to ask about the parentage, offspring color etc but if they have not bred back i+, F2 intercross it is not going to be easy to get clear answers. Always good to re-verify some things. Amusing how a seemingly simple question of 'what do you get out of white x black?' is in actuality such a complicated thing to answer.

Edited to add: on re-reading, I had missed some details- apparently some of the white birds exhibited blue leakage and some have grey legs. It seems the idea of II remains as the main cause in clearing the legs.

Does blue have a lightening effect on legs if combined with I? I suspect it does not but want confirmation..? I still cannot tell if there is probably something else undetected so far, such as barring, mottle or possible case of yellow leg blacks in their whites.


Edited by Kaalnek (08/01/17 01:41 PM)

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#116768 - 08/01/17 02:59 PM Re: Clear legs on whites [Re: Kaalnek]
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Ruler of the Roost

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Posts: 1141
Loc: Island of Fetlar, Shetland
I think birds with two factors for blue, that is splash birds, do have paler legs. This is apparent if you Google Image splash Jersey Giants.
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#116771 - 08/01/17 06:22 PM Re: Clear legs on whites [Re: Hen-Gen]
Kaalnek Offline
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Registered: 07/16/02
Posts: 415
Loc: California
You're right, some diluting effect on some splashes. Is splash, hom dom white enough to clear the legs though..? Plus Id..?

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#116772 - 08/01/17 09:00 PM Re: Clear legs on whites [Re: Kaalnek]
KazJaps Offline
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Registered: 08/30/02
Posts: 2799
Loc: Australia
Originally Posted By: Kaalnek
Thanks to both of you for answering.

I'd forgotten about the yellow leg blacks, that's a good point to consider. What's the most common/likely genotype for that by the way?


I posted a thread previously on an old Australian vet journal article on breeding yellow-legged blacks. The breeder thought there was a mutation "Ie", this sex-influenced autosomal incompletely dominant, that cleaned up E epidermal pigment (also produced bleached feather undercolour etc when homozygous in roosters).


I think this mutation segregating may have blurred previous research on the effects of I dominant white, mo mottled, E and ER alleles, etc on leg pigment. Unfortunately geneticists often used commercial stock like white leghorns, or Anconas etc in their test crosses, but not exhibition breeds that were required to have dark legs (eg Dutch Bantams, Belgian Bearded Bantams, etc). And because of this, there are great inconsistencies compared to their results on expression of leg pigment with mo, I, E, wheaten etc (eg Mottled/Millefleur, Pyle, Wheaten etc Belgians & Dutch with blue to black legs).

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#116773 - 08/01/17 10:12 PM Re: Clear legs on whites [Re: KazJaps]
KazJaps Offline
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From Poultry Breeding & Genetics (PB&G, 1990, pp 154-155):

Id locus alleles, effects of I dominant white:
Quote:
id^c. The id^c mutation occurred in the Cornell Randombred White Leghorn line (hence the c. superscript) and differed from id+ in that plumage and beak pigment is present in the dominant white (I/I) mutants (McGibbon, 1974).

id^M. The Massachusetts mutant appeared in a synthetic line derived from a cross between Black Langshan and a dominant white meat line. It differs from the above in that it is expressed in the shanks at day-old in black (E), birchen (ER), wild-type (e+) and recessive white (c) chicks. It produces the darkest shank color when combined with E. In the presence of c/c E/-, idM shank color is somewhat diluted, but it is still dark blue. The idM allele is not expressed in the shanks of dominant white (I) chicks, but the combination of I and E results in a pale blue or green color by I0-12 weeks of age.


Epidermal pigment (E and ER), effects of I dominant white:
Quote:
The major eumelanin shank pigment inhibitor is dominant white (I), which also removes black pigment from the feathers.

The secondary pattern genes sex-linked barring (B) and mottling (mo) also inhibit shank melanization. The effect of B is dose dependent, so males (B/B) have lighter shanks than do hemizygous females. Mottling is expressed in the shanks as small scattered black spots on a noneumelanized background.


---------------------
And Smyth's 1994 Melanin Pigmentation article:
Quote:
Dominant white's ability to suppress id+ is reduced in the presence of E. Here the shanks are clear at hatching but become pale green, or pale blue in white skin stock, over time.


I've had het. I/i+ E/wheaten or ER/wheaten, with both id+/- and Id/- (from Jap Id/Id roo and Orp id+/? roo x Jubilee Indian Game hen Id/-), & both daughter genotypes had very dark slate-black legs. I haven't bred I/I to know if the homozygote were diluted.

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#116775 - 08/03/17 06:53 AM Re: Clear legs on whites [Re: KazJaps]
Piet Offline
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Registered: 10/07/10
Posts: 262
Loc: Belgium
I crossed a Blue leghorn hen with an exchequer leghorn roo.
Both had nice yellow legs.
The blue pullet ofspring had dirty yellow legs.
I had seen this before in crosses (lose a dose of mottled?...) with exchequer leghorn that the pullets had not good quality yellow legs.But mostly The black pigment was stronger.
With the blue pullets it was more shine through gray and I think it got less obvious when they grew up.
The roos that came out of the crosses always had nice yellow legs.

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#116777 - 08/03/17 07:48 PM Re: Clear legs on whites [Re: Piet]
KazJaps Offline
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Registered: 08/30/02
Posts: 2799
Loc: Australia
That's interesting Piet. So the Exchequer Leghorn didn't have the same epidermal pigment diluter as the Blue Leghorn (assuming that both had ER or E alleles). Would the Blue Leghorn line be regarded as pullet-bred, eg did the males have excess white, bleached undercolour?

I had similar results with crossing the yellow-legged Black Jap roo (homozygous E or ER, Id/Id) with yellow-legged Jubilee Indian Game hen (double-laced, wheaten based, I/i+ Id/-). The i+/i+ black segregates were the same coloured legs as the I/i+ het. dominant whites. The daughters had slate/black legs as adults but the sons started dusky legged, matured to clean yellow-legged. So it was a sex-influenced result (although not sex-linked). Note, none of these were carrying mottled (& no exchequer in their background). The father Black Jap roo had bleached white undercolour, white at base of tail, etc (ie pullet-line phenotype).

Jeffrey (Bantam Breeding & Genetics 1977, p 156) noted that Cote (1976) had similar results with crossing a yellow-legged blue Cochin rooster with Brown Leghorn hens. Ie, even though all parents were Id & yellow-legged, the offspring had pigmented willow legs.

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