Comb type egg color

[ThiefPouter06]

I read on other posts that single comb will seldom lay blue/green eggs. So it would be correct to assume single comb EE roo 's do not carry blue genes? Now if you breed a sinlge comb EE (lets assume no blue gene) to a green egg laying hen, do normal mendellian genetics apply? For example if she was homozygous for blue, all hens would lay green, if she was hetero for blue, 50% would have the blue gene 50% would not? or is it more complicated than that?

 

[Sonoran Silkies]

It's a bit more complicated, but only a bit.

As to whether a hen lays blue or geen eggs, it depends on the other egg colour genes--of which there are many. If the genes are otherwise for white eggs, she will lay blue; if brown egg genes are present, she will lay green.

Back to the comb. The gene for pea comb is very, very close in location to the gene for blue eggs. As a result, these genes are almost always inherited together. You can reliably predict that only a very, very small percentage of birds who inherit one of these will not inherit the other. For the moment we'll ignore that small percentage as if it doesn't exist, but I have read that it is about 3%. I'm not sure if that is an accurate number or not.

If she is hom for blue eggs, she is also probably hom for pea comb. All her offspring will receive a copy of these alleles, which means the females will lay blue or green eggs depending on the other egg colour genes they inherit from both mama & papa.

If she is het for blue egg, then she is probably het for pea comb as well. About half her chicks will receive the blue egg allele and the pea comb allele and about half will not receive either.

Okay, back to your question--single combed roo paired to a green egg laying hen hom for the blue egg gene. All offspring will receive a single copy of pea comb & blue egg gene from the hen. Thus, they will all have pea combs and the daughters will lay a blue or green egg, depending on which other egg colour genes they inherit from each parent.

2nd scenario--single combed roo paired to a green egg laying hen het for the blue egg gene. Half the offspring will receive a single copy of pea comb & blue egg alleles from the hen; the other half will receive the single comb allele and the not-blue eggshell allele. Thus, half will have pea combs and these daughters will lay a blue or green egg, depending on which other egg colour genes they inherit from each parent. The other half will have single combs and those daughters will lay brown or white eggs, depending on the other egg colour genes.

 

[ThiefPouter06]

Quote:
So accept for the single comb carrying blue, normal dominant/recessive genetics apply. Now I have two more questions. If you cross a green egg layer/pea comb hen to a single comb rooster and single combed offspring occur (should be 50%) could you assume she is heterozygous for blue? If the majority of single combed hens dont carry blue then I would assume that a hen carrying single comb would be just as difficult for her to be pure for blue. Second, if single combed hen seldom carry blue would we assume single combed roos seldom carry blue as well?

 

[Sonoran Silkies]

If I understood your questions correctly, Yes. If a pea-combed hen & a single comb roo have single combed offspring, she cannot have passed on a pea comb gene as it is dominant. Since she didn't pass it on, she must have only had one copy. Since pea comb & blue egg are closely linked, she is almost certainly het for it, as well. Since neither pea comb nor blue egg are sex linked genes, then yes, you can make the same assumption about the rooster.

 

[CANDLE98]

So I have a pea combed roo, Are my chances of making a hen that lays blue eggs good if I mate him with a blue egg hen?

 

[ThiefPouter06]

Quote:
I think you followed me. Thanks. I think it would be much easier to look for single comb chicks than wait to see if the pullet offspring lay brown eggs to test to see if she is homozygous or het. for blue.
I would think that the chance for a homo. blue egg EE are very slim, since no one is breeding EE for 100% green eggs. I think it would be easier to get a pure araucana or ameraucana roo to try to get to 100% green. The you would a smaller chance of brown eggs. breeding for 100% green eggers will be a difficult task for sure.