Why is she laying a brown egg?

[Sonoran Silkies]

Quote:
I don't think that when you cross those two it's a lock that you will get green eggs. I purchased 2 olive eggers that had the same mother and father, one laid a green egg add the other laid a dark pink egg. I think the mom was EE and the father was a maran.

If I remember biology correctly then there is always a possibility of taking all of one parents genes, in a single area.hence the brown egg layer.

but I wouldn't worry about it it's a really low chance of that happening

Only for sex-linked genes. Each parent contributes a copy of every gene. If the parent has two genes with the same allele (homozygous), you KNOW that that is the copy that will be contributed from that parent; if the alleles for that gene are dissimilar (heterozygous), the parent could contribute either. Theoretically, the ameraucana father should be homozygous for the blue eggshell gene, and thus contribute it to all his progeny. However, if bred with other ameraucanas, then it is possible that he is heterozygous for the gene, but the homozygous mother always contributed a copy of the blue eggshell gene, thus all female offspring lay blue eggs.

First, as others have said, you need to rule out whether a different bird is laying the brown egg. If it is proven to be the ameraucana X rock, then test breed some other birds (or check with those whom you have sold birds to) to see if any others lay brown eggs.

 

[Sonoran Silkies]

Quote:
I don't think that when you cross those two it's a lock that you will get green eggs. I purchased 2 olive eggers that had the same mother and father, one laid a green egg add the other laid a dark pink egg. I think the mom was EE and the father was a maran.

If I remember biology correctly then there is always a possibility of taking all of one parents genes, in a single area.
hence the brown egg layer.

but I wouldn't worry about it it's a really low chance of that happening

That makes sense to me though because the mother was an EE. EEs are notoriously squirrely with the genetics because they are random mixes of lots of things. The only thing in common is a pure ameraucana parent along the way. Easter Egger is a catch all phrase, so the mother of your birds could have donated any number of egg color genes. It makes sense that it could have manifested in two different ways.

In this case though the mother was a brown egg layer. She only carries genes for brown eggs. That's it. The father only carries the blue egg gene. Thus all of their offspring should get one brown and one blue gene, meaning that the offspring's eggs would be blue washed with brown making green.

"If I remember biology correctly then there is always a possibility of taking all of one parents genes, in a single area."
This is what I need explained. Can they get only genes from one parent when it comes to egg color? I thought it was always a mix of the two.

The genes for brown eggs and blue eggs are entirely separate, unrelated genes. It is basically blue versus white eggshell for one gene (the O gene) and brown coating versus no coating for a number of other genes. There are also genes for shiny versus no shiny shells and genes that remove brown pigment, making the eggs whiter or bluer. THere are at least 13 separate genes that determine egg colour.


There is a big difference is stating that it is difficult to impossible to give a complete genotype on EEs because they can be such a mix of things, but with a first generation cross of two specific breeds, that statement is quite inaccurate. Basically, the bird in question has half the genes for a barred plymouth rock and half for a blue ameraucana.

edited for typos

 

[CityGirlintheCountry]

Thank you, Sonoran. That's what I needed. I had no idea that there were 13 genes that determine egg color. No wonder it is screwy.

 

[Sonoran Silkies]

At LEAST 13. Maybe more. At least one is sex-linked, but most are not.

 

[georgialee]

I had no idea there were that many genes for eggs!

The shiny egg gene is cool. I always wondered why some hens lay a matte egg and then the others lay the really smooth (almost impossible to candle without dropping) eggs.

Thanks for the info

 

[tadkerson]

Quote:
I will be repeating some information posted by others, please excuse me if I do not give others credit for their contribution to the discussion.

Genetics 101

Nicole was the first person to answer the question. The blue egg shell allele is dominant to the white egg shell allele. If you could turn the father into a hen he would lay blue shelled eggs. He carried one allele for blue egg shell and another allele for white egg shell. He can give only one allele to his offspring. He could either give a blue egg shell allele to his offspring or give a white egg shell allele to his offspring. He can not give both alleles to his offspring.

The mother is a brown egg shell bird therefore she can only give a white egg shell allele to the offspring. Her offspring will carry two white shell alleles (one allele from mom and one allele from dad) or carry a white egg shell allele (from mom) and a blue egg shell allele (from dad). The hen will also give some brown egg shell genes to its offspring. There is more than one gene that causes brown egg shell color, could be as many as twelve- I think it is fewer.

The mother could give any number of brown egg shell genes to the offspring- therefore all of the offspring will inherit the brown egg shell characteristic. The pullet that lays the brown egg inherited a white shell allele from dad and a white egg shell allele from the mother. The brown egg shell genes the pullet inherited from the mother caused a white egg shell to become brown.

Tim

 

[CityGirlintheCountry]

Thanks, Tim. That makes total sense. I guess I was just assuming that the ameraucana rooster carried two alleles for blue eggs since he is pure ameraucana. The resulting brown egg makes sense if he only carries the one allele.

So theoretically 50% of his offspring carry the blue egg allele and 50% carry the white egg allele, right? If we assume that all of my hens are 100% blue egg allele, then half of his offspring will only carry one blue egg allele. If we assume that some of the hens are also 50% blue/50% white it is then possible that some of these ameraucanas will lay white eggs? That is very disappointing. I spent a lot of money to purchase my original stock from well known breeders. I feel gypped. The whole point of ameraucanas is the blue eggs. Arg.

 

[NicoleRM]

To me, this is the hardest part of breeding for certain egg colors. Figuring out what your rooster carries takes a lot of test mating and growing out pullets to see what they lay and is (at least to me) very important since he gives half the genetic makeup to your whole project. You can do some preliminary culls based on comb if you cross to a single combed hen, but as in this case, the pea comb and blue egg alleles are not always inherited together.

 

[tadkerson]

I decided my comments did not make sense- so I deleted them.



Tim

 

[SteveH]

Quote:
It's not talked about a lot, but I've discovered that even some [maybe many or all] of the most reputable breeders of Ameraucanas still have a few birds carrying only one copy for blue eggs............................. also muffs/beard, and occassionally a copy for yellow skin. Ameraucanas are still in their infancy as a breed. Some intentionally choose to use these birds due to the fact they have other qualities that the breeder thinks they might use to improove the flock towards the SOP; it's a matter of the breeder's priorities. They've made much progress, so there's still an obvious advantage in going to a reputable breeder to buy Ameraucanas, but you're still going to find some of them that I label as EEs.