Any difference in egg shell color of homozygote vs. heterozygote blue egger?

Discussion in 'Exhibition, Genetics, & Breeding to the SOP' started by QueenMisha, May 9, 2016.

  1. QueenMisha

    QueenMisha Queen of the Coop

    Let's say you have one homozygote and one heterozygote blue egg layer. No brown egg genes involved, one is, say, a pure Ameraucana and the other is a hybrid of Ameraucana and a white egg layer, let's say Leghorn since they lay such a chalk white egg. Would their egg shell colors be different? Would one be paler? If they are different, will it be noticeable or subtle?

    Another scenario. Brown egg genes are involved, let's say just a few of them so the color is a light green. Both have identical brown egg shell genes but one is a heterozygote and the other a homozygote for the blue egg gene. Is there a difference in color? Shade? Intensity.

  2. Wappoke

    Wappoke Chirping

    Dec 5, 2015
    I have personal experience with crossing leghorns and blue egg layers. Leghorns carry genes that inhibit the production of protoporphyrin-IX,which causes the brown color in and on the egg shell. The pigment biliverdin-IX produces the blue egg shell color. Both of the pigments are produced in the epithelial cells of the chicken uterus- the same genes that effect brown pigment production also effect blue pigment production and this effect causes the hybrids to lay a very pale blue egg. The precursor to blue pigments and brown pigments are most likely the same substance- if the genes effect the precursor (which may be the case) then both pigments will be effected.(source: Comparison of the total amount of eggshell pigments in Dongxiang brown-shelled eggs and Dongxiang blue-shelled eggs)

    I also crossed my blue eggers with spitzhauben and it produced the same effect.

    I believe that at least two of the genes that effect brown egg color are incompletely dominant so if a bird is heterozygous or homozygous can make a big difference.

    Read and digest the following white paper.
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