Is egg color genetics really male driven?

[Cycomiko]

My goal is to hatch blue feathered fibro pullets that lays green eggs. I've read it must be a Splash colored male (Silverudd, green egg gene) with and a full fibro pullet (Svart Hona, white egg)[A]. I have that. But I also have Svart Hona cockerels with a few splash Silverudd pullets. I don't get how the egg color would differ in between A and B, and I would love to mix the genetics of the birds across more blood lines. Because honestly, these are two of the best breeds I've ever raised. To get a generational BBS fibro green egg layer would be ideal, and diversifing genetics would be ideal.

 

[Cycomiko]

.... And the experiment begins. 4 Svart roo x Silverudd eggs and 5 Silverudd roo x Svart eggs... I in no way wanted to have a broody hen in January, in western Maryland, with over 30" of snow forecasted left this winter, on a mountain at that. But the present day weather
, after a freeze, gave us a 50 degree Sunday day, and even on the next day wintery mix day, couldn't break a Svart girl that went broody, so we're going to start now. Close monitoring for dehydration, I'm worried more for the mom that the chicks. One of the two bloodlines of Svarts we have is very broody. So hard to break. I gave her the eggs at 5pm this evening, and she immediately started putting them into place.

 

[DarJones]

The genes you are working with are brown egg, blue egg, and white egg.

In your breeds, the only blue is the South American variant of oocyanin. It is a dominant gene meaning that any hen with one copy of the gene will lay a blue tinted egg.

I was able to identify 3 separate genes that produce white eggs. The most desirable is the intense white as found in leghorns. The other two genes produce a washed out version of white egg shell. This does not mean that there are only three genes involved, it just means that I was able to pick out results showing at least 3 are out there in different breeds. It is important to understand that all chicken eggs start out white and are either tinted blue by the oocyanin gene or are coated brown by porphyrin.

Brown eggs are a whole nother ball of wax. There is an entire biopath dedicated to coating eggs with porphyrin. All chickens have the porphyrin biopath, but in breeds that lay white eggs, it is interrupted at one or more places to turn off the brown coating. A study of the literature showed at least 7 different genes in the porphyrin biopath with mutations in at least 3 producing white eggs. A chromosome translocation with a lot of undesirable side effects is one variation that produces white eggs. If you are crossing a green egg layer with a white egg layer, you will wind up with segregation for some brown egg layers, some white egg layers, some sky blue egg layers, and some olive egg layers. The ratios I got were 8 brown, 1 white, 1 sky blue, and 6 olive. The number of chickens I raised was not high enough to confirm this as a verifiable and repeatable result so use this with caution.

IMO, after about 4 or 5 generations of selecting for oocyanin, it would be a really good idea to dna test for the blue egg gene and try to identify a couple of homozygous roosters. Why? If a rooster with two copies of the blue egg gene mates with a random group of hens that all lay blue eggs, the next generation should all lay blue/green eggs and about 5/8 should be homozygous for the oocyanin gene.

Also worth knowing, if you combine a white egg gene with a blue egg gene, the result is sky blue eggs. In other words, with the porphyrin biopath disabled, the eggs will not be coated and will not appear greenish/brown.

 

[Willawong Hill]

I think both the genes for egg colour and egg coating are supplied by both parents, so your svart honas will supply genes for white eggs, no colour coating and the silverudds will supply genes for blue eggs, brown coating no matter the gender of either party. You should end up with green egg layers (or carrying green egg gene) for all the F1s, it will be the generation after that where things will get interesting with eggs of all colours as some will inherit the blue and some the white and some the brown tint and some not. Would love to know the outcome so keep us updated with pics.

 

[NatJ]

Sex-linked genes are the only ones where it matters which parent has that trait.
Most egg color genes are not sex-linked (blue or not, and shades of brown).

I've read that there is one particular sex-linked gene that causes white eggs.
So certain crosses of white layer x brown layer give different color eggs depending on which parent is which breed--the hen gets whatever gene her father had.

But I don't know if that gene is present in all white egg layers, or if some white eggs are caused by a different combination of genes. I suppose you will know more in a year or so, if your pullets from one cross lay blue eggs and from the other cross lay green

 

[Willawong Hill]

As far as I'm aware both parents contribute to the egg colour so I don't see how egg colours would be different as an average between your two groups.

 

[Cycomiko]

I think both the genes for egg colour and egg coating are supplied by both parents, so your svart honas will supply genes for white eggs, no colour coating and the silverudds will supply genes for blue eggs, brown coating no matter the gender of either party. You should end up with green egg layers (or carrying green egg gene) for all the F1s, it will be the generation after that where things will get interesting with eggs of all colours as some will inherit the blue and some the white and some the brown tint and some not. Would love to know the outcome so keep us updated with pics.

Thanks, I wasn't even thinking past F1 in egg color. This will be an excellent long term project for my homeschooled son. I will indeed follow up in the future!

 

[Kusanar]

.... And the experiment begins. 4 Svart roo x Silverudd eggs and 5 Silverudd roo x Svart eggs... I in no way wanted to have a broody hen in January, in western Maryland, with over 30" of snow forecasted left this winter, on a mountain at that. But the present day weather
, after a freeze, gave us a 50 degree Sunday day, and even on the next day wintery mix day, couldn't break a Svart girl that went broody, so we're going to start now. Close monitoring for dehydration, I'm worried more for the mom that the chicks. One of the two bloodlines of Svarts we have is very broody. So hard to break. I gave her the eggs at 5pm this evening, and she immediately started putting them into place. View attachment 2474772

She will make a very nice angry pancake (broody) with the added bonus of also being an angry void.

 

[Kusanar]

.... And the experiment begins. 4 Svart roo x Silverudd eggs and 5 Silverudd roo x Svart eggs... I in no way wanted to have a broody hen in January, in western Maryland, with over 30" of snow forecasted left this winter, on a mountain at that. But the present day weather
, after a freeze, gave us a 50 degree Sunday day, and even on the next day wintery mix day, couldn't break a Svart girl that went broody, so we're going to start now. Close monitoring for dehydration, I'm worried more for the mom that the chicks. One of the two bloodlines of Svarts we have is very broody. So hard to break. I gave her the eggs at 5pm this evening, and she immediately started putting them into place. View attachment 2474772

Oh, and one thing to think about, since you can't tell by looking which gene the rooster got (because obviously he doesn't lay eggs), once you start crossing, you might want to only use the rooster that gives the egg color you want.

For example, F1 should lay all green eggs due to the cross
F2 could lay any color but who knows what color the cockerals "lay" so they are your mystery element, if you cull all hens that lay different color eggs, then breed them back to your green layer rooster, then all of their kids in the F3 generation SHOULD have just the green egg genes because you know their mothers only have green genes (they lay green eggs) and you know their father is also a green egger due to his breed.

After that F3 generation you should be able to breed them between themselves and back to the green eggers from the starting generation to get the traits you need as long as you don't outcross again to another color of egg layer the green eggs should be more or less fixed in your "breed" you are starting.

 

[DarJones]

I am not aware of any single document that describe the white egg color genes, but if you delve around, there are plenty of articles that break down the genetics to one degree or another. For example, the chromosome translocation that causes one form of white egg also reduces size of eggs and number of eggs produced. I have reason to believe this chromosome deletion may be in some populations of cream legbars based on the description of birds after a few generations of selection for enhanced blue egg color.

When the intense white egg gene(s) is present, it almost totally suppresses production of porphyrin. You can detect the porphyrin gene by dipping the egg in water and drying it off with a paper towel. The porphyrin will be easily seen on the shell of the slightly damp egg. In a cross between a white egg layer and a green egg layer, porphyrin will be present in the F1 but can segregate with a small percentage of blue egg layers in the F2. The results I got were about 1 sky blue egg layer out of 16 chicks hatched. Note that I am NOT including green or tan over blue egg layers in this number.