Egg Colour Genetics

[mccmeadows]

The chickens aren’t even hatched yet, but I have a couple egg colour genetic questions. Our first group of chicks we got last year have been laying us some beautiful coloured eggs, but quite a few do lay brown eggs. I understand that this is a kick back of having barnyard mixes.

If I breed true coloured layers to other coloured breeds (ie. Ameraucana to Cream Crested Legbar, Cream Crested Legbar to Silverudd Isbar, etc.), will I run into that possibility of brown eggs or will they all be coloured layers?

 

[Ridgerunner]

Let's discuss genetics first. There is one gene pair that determines if the egg will be base blue or base white. Blue is dominant so if just one of the two genes at that gene pair is the blue gene the hen will lay a base blue egg. Brown and green is just brown added to a white or blue egg. So:

Blue + no Brown = Blue
Blue + Brown = Green
White + no Brown = White
White + Brown = Brown

There are a lot of different gene pairs that affect the shade of brown, that's why you can get so many different shades of Brown or Green.

The three breeds you mentioned are supposed to have both genes at that gene pair to be the blue version of that gene, so if they are true representatives of their breed and you breed them to another true representative of one of those breeds then any pullets you get will lay colored eggs. I'm being a bit careful how I phrase this because you sometimes run into the problem that although somebody claims their birds are true breeds, they really aren't. They are not always being malicious liars, sometimes they just don't know any better. You can't tell by looking. Roosters don't lay eggs so there is nothing to see, but even with an egg from a hen if just one of her genes is the blue gene she'll lay a colored egg.

If you ever get a white or brown egg from crossing those breeds it means they weren't true to their breed. But if they are you will always get a blue or green egg.

 

[mccmeadows]

Let's discuss genetics first. There is one gene pair that determines if the egg will be base blue or base white. Blue is dominant so if just one of the two genes at that gene pair is the blue gene the hen will lay a base blue egg. Brown and green is just brown added to a white or blue egg. So:

Blue + no Brown = Blue
Blue + Brown = Green
White + no Brown = White
White + Brown = Brown

There are a lot of different gene pairs that affect the shade of brown, that's why you can get so many different shades of Brown or Green.

The three breeds you mentioned are supposed to have both genes at that gene pair to be the blue version of that gene, so if they are true representatives of their breed and you breed them to another true representative of one of those breeds then any pullets you get will lay colored eggs. I'm being a bit careful how I phrase this because you sometimes run into the problem that although somebody claims their birds are true breeds, they really aren't. They are not always being malicious liars, sometimes they just don't know any better. You can't tell by looking. Roosters don't lay eggs so there is nothing to see, but even with an egg from a hen if just one of her genes is the blue gene she'll lay a colored egg.

If you ever get a white or brown egg from crossing those breeds it means they weren't true to their breed. But if they are you will always get a blue or green egg.

Great, that’s definitely the answer I was looking for! Hoping I end up with good lines that allow me to end up with only coloured layers then