Chicken Egg Color Genetics Discussion

[Skipper81]

Yup I've read alot on this but you explained it much better I'm saving your post thank you

 

[Brahma Chicken5000]

Every egg starts as white. Then they have two genes either the blue egg gene or non blue egg gene. (We'll call non blue white for conversations sake)
Yes blue is dominate to white
Of course they can have one blue and one white or two blues or two whites.
The genes for brown is separate and yes involves several different genes all of which aren't know. The different brown genes are why there's such a variety of shades of brown.
Lets go back to white and blue. We'll call it step one. You know how it works. Each chicken has two genes and pass one of their two to their offspring.
Isbars are pure for blue eggs and pass blue egg genes to all their offspring. In step one they are just as ameraucana or legbars they breed true for blue.
Step two is brown egg genes. No there is no green egg gene. Its just a matter of having blue and brown genes in the same bird. Brown genes on white make brown. Brown on blue makes green.
Isbars also carry brown genes so they pass one of their two blue genes and their brown egg genes to their offspring. They breed true to green because they get blue and brown from both parents.
If you look at olive eggs you can see how they came about. To get olive eggs or green eggs you cross in brown egg genes into a bird with blue egg genes.
Brown egg layers have two white egg genes so when you bring in the brown you bring in white. The offspring then have one blue gene and one white egg gene then also brown egg genes. If you then cross those together you can get one blue gene and one white gene (50%) two white genes (25%) or two blue genes (25%) the brown genes or at least some of them are going along for the ride.
With isbars selective breeding resulted in getting two blue genes and brown genes in the same bird so unless you cross in white egg genes they have no choice but to breed true for blue and brown so results in green eggs.
That's what olive eggs strive for. Problem with them is that when selective breeding to get the two blue genes back together you lose some of the brown genes so the eggs result in lighter then olive green. Breeders then breed back to a dark brown layer to darken their green eggs. When doing that they bring back in a white egg gene and have to start over in trying to get pure for blue again.
Hope that makes sense.

Thank you for that very informative post. Thank you for clearing up a few things for me. So if I understand correctly Isbars have the blue egg gene as well as a brown egg gene in their makeup.

 

[Skipper81]

That would mean isbars are a pure green egg layer from what I'm getting

 

[The Moonshiner]

Thank you for that very informative post. Thank you for clearing up a few things for me. So if I understand correctly Isbars have the blue egg gene as well as a brown egg gene in their makeup.

Yes isbars are pure for blue eggs. Two blue egg genes. They also have brown egg genes.
Egg color is two parts.
Part one is blue/ non blue (white)
Every chicken has either two blue egg genes, two white egg genes or one blue/ one white.
They're going to pass one of their genes to their offspring. So if they have one of each or if what they're bred to has one of each or what they are bred to has the opposite color as them then they won't breed true.
Part two is the brown genes. They work separately and are controlled by several genes. A chicken can have none of those genes to many of them. That results in the wide range of shades of brown.
Brown is like a paint being added on top of the blue or white egg.
Lets just say there's 7 genes and each represents a different color of brown.
Like 7 cans of spray paint. One or more may be empty. The others vary from a light cream to a dark brown.
I don't know exactly how it works and am unsure if anyone knows exactly but...those genes are passed on to offspring as well. Its like spraying paint on the eggs right before they go out the door.
Some birds will just have empty cans and no color change will happen. Others have anywhere from one can with paint to all cans with paint. Whatever they have is sprayed on. Depending what and how many shades are added determines the final shade or darkness of brown. On white eggs its brown. On blue its green.
When you add brown it is uncertain how it will go from generation to generation. But it is hard to get rid of completely once its in. Its also not automatic. Just because a bird lays a very dark egg doesn't mean its offspring has to also.
Like marans you have to selectively breed for the darkess eggs to continue. If you pay no attention to the shade then over generations it will lighten. On the flip side if you breed with that as a priority you can get darker shades over generations.
Back to brown being spray paint. With the spay paint example if you just breed and breed and breed without watching what paint you have it is no telling where you will end up.
If you're breeding with the cans of paint (brown genes) in mind you can selectively breed for what you want.
If you start running out of paints and what darker eggs you have to keep an eye on them and bring in a new box of paints in when your color starts running out. Bringing a new box of paints is like bringing in a new chicken or breed.
If you want it lighter or the brown out completely you bring in boxes with less cans with paint in them or lighter shades. Darker you bring in darker color browns and as many cans with paint as you can.
It always goes back to the blue and white too though. Brown brings in white genes so you have to juggle the brown for what you want while always chasing getting two white genes or two blue genes to breed true for egg color.
Along the lines when creating the isbars they got the brown genes added to blue egg layers. They then got back to pure (two genes) blue egg layers while maintaining enough of and the right ones of the brown genes for them to breed as consistently as can be expected from generation to generation.
Maybe that can give a round about way of how it works.

 

[Brahma Chicken5000]

So a chicken’s egg genes are represented like this: (O,O) would mean that the chicken has two blue egg genes and this (o,o) means the chicken has two non blue (white) egg genes. So if we say that the brown egg gene is represented by “b” a chicken with that lays green eggs will have (O,b) genes and a chicken with (b,b) will lay a brown egg and it’s shade is dependant in the number of cans it has.
Is the brown egg gene dominant? I imagine it is at least dominant to white, but I’m not so sure about blue.

 

[The Moonshiner]

O is blue. o is white and brown is more like x,y,z.
(OO) pure for blue
(oo) pure for white
(Oo) blue egg but carries white
(oo) (x or y or z or any combination) is brown
Green can be (OO) (x or y or z or any combo)
Or
(Oo) (x or y or z or any combo)
You just need to look at it as two separate things.
Part one is (OO) (Oo) or (oo) blue or white or both.
Part two is completely separate. Don't put it in the same ( ) as O or o.
Look at it as (x,y,z or whatever in their own ( ).

 

[The Moonshiner]

Brown isn't dominate to white or blue its just on top of blue or white.

 

[Brahma Chicken5000]

Brown isn't dominate to white or blue its just on top of blue or white.

Thanks for clearing that up for me and taking the time to answer my questions. Would this be a correct way to write the brown egg gene (x/y/z/any combo)?

 

[The Moonshiner]

Ha
I have no idea what the brown egg genes are called or what their symbols are.
I just used xyz to explain things.
I haven't learned much about genetics from books so I don't know their symbols.
Most of what I know is from breeding and figuring it out along the way. When something has me stumped I will look into info but my brain doesn't work with genetics like its written in books or written by experts.
I just look at it how it makes sense to me and try to explain it the way it may make sense to someone else.

 

[Brahma Chicken5000]

Ha
I have no idea what the brown egg genes are called or what their symbols are.
I just used xyz to explain things.
I haven't learned much about genetics from books so I don't know their symbols.
Most of what I know is from breeding and figuring it out along the way. When something has me stumped I will look into info but my brain doesn't work with genetics like its written in books or written by experts.
I just look at it how it makes sense to me and try to explain it the way it may make sense to someone else.

Oh. Well the way you explained it to me was very easy to comprehend. You’re like a genetics guru