Finding the homozygous cushion comb

Discussion in 'Exhibition, Genetics, & Breeding to the SOP' started by Triplehorn, Oct 31, 2015.

  1. Triplehorn

    Triplehorn In the Brooder

    Oct 15, 2013
    Fairbanks, Alaska
    Is there a way to pick out the homozygous cushion comb (RRPP) from approx 50 birds that should be 75% heterozygous for cushion comb and 25% homozygous? At any age? I understand that Pea comb has incomplete dominance, so the smallest combs could be homozygous PP, but I've found no evidence that the smaller comb indicates homozygous RR. I want to minimize the amount of test breeding I have to do.
    Last edited: Nov 5, 2015

  2. IceAngel

    IceAngel Songster

    May 2, 2013
    I am not an expert when it comes to chicken genetics. In general, however, f we are talking about simple genes, however, you will not be able to tell the difference between a homozygous dominant carrier and the heterozygous version of the trait without test breeding. Things get more complicated when it comes to incomplete dominance because there could be degrees of it. Are you sure that the trait isn't polygenetic?
  3. varidgerunner

    varidgerunner Songster

    Aug 16, 2013
  4. Triplehorn

    Triplehorn In the Brooder

    Oct 15, 2013
    Fairbanks, Alaska
    Thanks Ridgerunner.
    I've read that post and many more. I believe that I understand the Punnett square analysis of cushion comb genetics. What I'm trying to ask for is hands-on breeder experience where someone has actually looked at a suite of birds that are both homozygous for cushion comb (RRPP) and heterozygous (RrPp, RRPp, RrPP, etc.).
    I assume that there must be several folks out there that have real world experience with this, because it must be done every time someone tries to create a true breeding cushion combed breed, or purify a breed that is supposed to be cushion combed that has other combs pop up from time to time.
    I thought perhaps someone has noticed a difference as chicks that might indicate homozygous, or maybe a difference at a few weeks, or even later in life.
    I can test breed, but I thought it worth asking before I had to recreate the wheel.
    Thanks in advance
    Last edited: Nov 4, 2015

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