How 'bout a quick tutorial on the genetics of White?

Discussion in 'General breed discussions & FAQ' started by SusanJoM, Aug 16, 2008.

  1. SusanJoM

    SusanJoM Songster

    I think I've read that White is a dominant trait and "covers" or "hides" lots of other color traits. I hatched out a white silkie girl, and I'm guessing that I wouldn't even know what's in her background until I've bred her to another white?

    But....I don't have another white. In silkie roos, so far, I seem to have just a black, a cuckoo and a splash.

    Should I just divest myself of the white hen? I'm not particularly interested in breeding whites, but I don't know if she might be useful to me for some other interesting colors? What about a white hen and a cuckoo roo. (I think the cuckoo is carried by the roo....)

    Just curious???

  2. MissPrissy

    MissPrissy Crowing

    May 7, 2007
    Forks, Virginia
    I don't know alot about white. I do know there is a dominant and a recessive white and a bird can have the recessive white hiding under the dominant white.
  3. SusanJoM

    SusanJoM Songster

    Quote:Shoulda known that something so plain would be not so plain at all, huh.....??? These chickens....they are always teaching me something....

  4. seriousbill

    seriousbill Songster

    May 4, 2008
    My understanding is that there are three main genes that produce a white coloration in chickens: silver (S), dominant white (I), recessive white (c).

    *Silver is sex-linked and dominant over gold.
    *Dominant white is, well, dominant, but it is a "leaky" gene that allows spots to show through. It inhibits the expression of black pigment.
    *Recessive white needs two copies to express, but it produces a clean white bird.

    Miss P is right in that white birds sometimes have more than one kind of white involved.

    Anyone feel free to correct or elaborate on the above.

    You need to know which kind of white you're dealing with in order to know what to expect from breeding.
    Last edited: Aug 16, 2008
  5. tiki244

    tiki244 Flock Mistress

    Jan 1, 2008
    I hope this isn't hijacking, but, I have some silver white Silkie chicks. What does that mean for breeding? And some of them may be splash when they get older.
  6. Kev

    Kev Crowing

    Jan 13, 2008
    Sun City, California
    seriousbill summed it up excellently.

    I would add that silver is often added to white birds for the reason that whites often does not cover up gold base colors as well, so sometimes adding silver makes for a "cleaner" white. This tends to be the case with Dominant White, which does not cover up gold very well- in fact some buff birds have Dominant White.. add silver, and poof, those buff birds would turn solid white(I think.. unless there are various other genes I'm not aware of- solid buffs are complicated creatures..) All "sex links" with white tails have Dominant White.

    Some people think silver also helps with brassiness.

    Almost all silkies have recessive white, it's been said that dominant white tends to repress skin pigmentation(this includes eyes) to some extent.. which is not desirable in silkies.

    For this reason, Susan, assume your white is a recessive white so unless any of the colored birds happen to be carrying recessive white, all offspring will be colored. What color they will be depends on what color the white is "underneath". Could be partridge.. black.. or..

    Cuckoo is really simply a combination gene for the barring on a black bird. This barring is sex linked. It does not mean it's "carried by the male" just that it has a particular inheritance pattern of the males being able to pass it on to offspring of both sexes while the females can only pass it to her sons. So your cuckoo rooster would produce cuckoos in both sexes. However if you had a cuckoo hen and bred her with black rooster(remember cuckoo is a Black chicken with barring..) the sons will be barred and females solid black. That's why it has the sex linked label.
  7. SusanJoM

    SusanJoM Songster

    Quote:Excellent, cool, and yahoo!!!

    Thanks, Kev, for the help. I still get really confused about those sex-linked characteristics, and the way they get passed from generation to generation. Luckily for me some of you are willing to repeat and repeat and repeat. It IS rocket science as far as I'm concerned....

  8. Kev

    Kev Crowing

    Jan 13, 2008
    Sun City, California
    Not a problem. [​IMG]

    Not sure if this will help, will give it a shot..

    For simplicity's sake here.. you know how the sex chromosomes for men are XY and XX for women? OK, in birds, this is reversed. Hens are XY and roosters XX.

    Sex linked genes are genes found on the part of the X that is missing on the Y counterpart. The Y chromosome is much smaller than it's X partner & has sections missing from it. Y has far fewer genes as a result. So the Barred gene mutant is found on a spot of the X that's missing on the Y.

    A hen being XY, could be looked at as the "sex determining parent". If she passes down the X, a son happens. If she passes down the Y a daughter happens. Along those lines, the sex linked gene gets passed with the X but not the Y.. so the boys get it from her but the daughters don't..

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