Chicken Genetics

[BarnyardCross]

Hey, so I would like to know a bit more information about chicken genetics. I enjoy genetics, and I basically just want to share what I know with others and hear from others what I don’t know.

Some of what I know (Just what I can remember of the top of my head):
Egg Color:
A chicken egg’s color is sourced from it’s two layers. The first being the calcium shell and the second being the layer of dye applied on the outside. The calcium layer comes in two colors, white and blue. Blue is dominant and white is recessive. The outer dye comes in two variations, brown and clear. Brown is dominant and clear is recessive. A brown egg has white calcium and brown dye. A blue egg has blue calcium and clear dye. A green egg has blue calcium and brown dye. Due to the variation in color of brown eggs and blue eggs, one can infer that these colorations are polygenic.
Silkie Chickens:
Silkie feathers are recessive.
Silkies exist in a non bantam form in Europe, but when silkies were brought to the US, only bantams were brought.
Frizzled feathers:
Frizzle feathers are lightly curled, and Belong to a gene that follows incomplete dominance. When the gene is homozygous the feathers are very curled and sparse. When the gene is homozygous it is called frazzled and it can be unhealthy for the bird, also cold tolerance is sharply reduced.
Bird size:
The size of the chicken is more heavily controlled by the size of the egg. A bantam hen will have smaller offspring then a standard hen, if their partners belong to the opposite size.
Polish Chickens:
They’re feathered heads must follow incomplete dominance, because pictures of hybrids still have the feathered heads, just a lot smaller.
What I want to know about:
The genetics behind the elusive pink egg. Croad Langshans can lay purple eggs, and I hear the common statistic that 5% of Easter eggers lay pink eggs. Why is this true?
Please share any information I didn’t mention.

(Please excuse any grammar errors)

 

[SunHwaKwon]

You could say there is a third layer, the bloom, that can be clear or tinted. I'm pretty sure it's different from the "ink". For instance, Langshans lay a brown egg (ie white calcium and brown tint) but some have a bloom that gives the egg a purplish hue. I wonder if that is the same thing going on with the so called pink egg. My bantam Brahma used to lay a pink egg. Either she has stopped laying or her egg color has changed, though.

 

[BarnyardCross]

You could say there is a third layer, the bloom, that can be clear or tinted. I'm pretty sure it's different from the "ink". For instance, Langshans lay a brown egg (ie white calcium and brown tint) but some have a bloom that gives the egg a purplish hue. I wonder if that is the same thing going on with the so called pink egg. My bantam Brahma used to lay a pink egg. Either she has stopped laying or her egg color has changed, though.

Yes, when hearing about Croad Langshan laying purple eggs, the word bloom was often repeated. I had previously assumed it was a reference to the natural dye on the outside of the egg. It is interesting to hear that it is a different layer of the egg. Can't wait to see what others have to share about it, and it is still confusing why the descendants of a blue egg laying chicken and a brown egg laying chicken would suddenly inherit this pink "bloom".

 

[SunHwaKwon]

I believe it is a combination of randomization of genetics and then selective breeding Hence why only specific lines have this trait. The same could be said for any trait that was selectively bred for - like melanization, large egg size, dark chocolate coloration, and high productivity/low broodiness. Another example would be "silver" labs, or really any color pattern in the chickens, which appeared randomly and then were selectively bred for.

 

[R2elk]

The calcium layer comes in two colors, white and blue.

The Calcium layer is white only. White eggs are due to the lack of any dyes applied. Blue eggs are the result of oocyanin applied to the white shell. It appears to be applied earlier in the cycle and penetrates the shell more fully than do the multitude of brown dyes.

There is no such thing as blue Calcium.

Chemical analysis has proven that the brown dyes also penetrate to the inner part of the shell. It does not penetrate as well as the oocyanin and does give the appearance to the eye that it is only an overlay.