Some Questions About Chicken Genetics

[myawesomepullets]

Hey! I'm continuing my quest to learn chicken genetics.
I want to know more about silkie, frizzle, and sizzle alleles, mainly the frizzle/sizzle ones. I know that H+/H+ and H+/h would be normal (non-silkie) feathering, and h/h is silkie feathering, but I don't know how the frizzle/sizzle genes come into play.
I also want to more fully understand barring/crele/cuckoo, and how the barring darkness and width is controlled by genotypes. I know that it is sex-linked (B/_ is a barred female and B/B is a barred male) and I know these combos as well: E/E & B/B is a cuckoo male (I think?) and e+/e+ & B/B is a crele male?
The next main thing that I don't know a lot about yet is how black and white is expressed and what genes/alleles show them. This could be wrong, but I think that extended black will mostly cover the chicken, but not totally (as seen in red leaking in black sexlink hens)?
Please correct me if any of this is wrong!

Thank you!!

 

[pipdzipdnreadytogo]

Frizzling has its own gene separate from silkied feathering, denoted by F. The gene is partially dominant with one copy giving the bird frizzled feathering and two copies making that feathering extremely frizzled. Individuals with two copies, F/F, known as being 'frazzled' rather than frizzled, also tend to have brittle feathering, metabolic problems, heart enlargement, and other health issues, so the best looking frizzles, and those produced by responsible breeders, are heterozygous for the gene, F/f+.

Now, Sizzle, that one confuses me a bit because people use the term in different ways. Most of the sources I've seen have indicated that 'Sizzle' is a term that simply means a bird that looks like a Silkie but without the silkie-feather gene, and instead with frizzled feathering. If you're talking about a silkied and frizzled bird, that would most likely be h/h F/f+. The genes are unrelated and can exist with each other or without.


I believe you are correct on cuckoo and crele. I have heard that cuckoo is a fast feathering bird that is black barred, and barred is a slow feathering bird that is black barred, but there is conflicting information out there as to how true that is.

Barring is technically partially dominant, causing narrow white stripes when one copy is present and wider white stripes when two copies are present, but since it is also sexlinked and exists on the Z chromosome, hens can only present phenotypically as heterozygotes, or individuals with only one copy of the gene. In birds, males have matching sex chromosomes, ZZ, and females have mismatched sex chromosomes, ZW. Because barring could be present on either one or both of a male's Z chromosomes, they can present as heterozygous (dark barred from having one copy of the gene) or homozygous (light barred from having two copies of the gene) for the gene. Was that what you were looking for for answers there?


The reason that black sexlinks have color leakage is because they are generally from a cross between a red male (which would be E^Wh/E^Wh at the E locus if I remember right) and a black barred female (E/E at the E locus), so they end up being E/E^Wh and that allows color to leak through. I have heard that there are other genes contributing to the 'completeness' of extended black covering everything as well, but I admittedly don't know much about those genes.

Hopefully someone with more knowledge on that front will pop in to explain that better!


Edited slightly for some clarity.