True or False? Olive egg genetics.

[The Kooky Kiwi]

... already hatched @300 chicks ........ hatching out about 200 more before stopping for the season.

....the way to answer the question in the real world is easy to set up.

Holy SMOKES that's a lot of birds. And you'll keep ALL the hens as layers?
I'm not sure that's a setup that many of us would find "easy"
BUT.. I'm actually genuinely curious to see what the numbers say for you because I also like to see how things stack up in "actual" results vs "theoretical probabilities".

 

[nicalandia]

How about you set up a breeding flock of brown X blue layers and hatch out 320 F2 chicks (160 females) then count how many lay blue eggs. This should conclusively demonstrate how many genes are involved in turning off porphyrin production. I'll even suggest which breeds would work really well. Get some Whiting Blue hens and use a good brown egg laying breed like Wyandottes for roosters.

I'll even up the ante. I've already hatched @300 chicks from my birds in 2021. I'll be hatching out about 200 more before stopping for the season. I'll track the number of blue egg layers and see how the ratio stacks up.

This is not intended to be confrontational. I am simply stating that the way to answer the question in the real world is easy to set up.

I am not interested on a backyard breeding project that will fail to shed more light on the very complex nature of egg shell color. Do you think 300 or even 1000 is enough? Its rarely enough to test linkage groups of one or two linked mutations. Were did you came up with the 1/16th chance? i am genuinely curious.

 

[DarJones]

And you'll keep ALL the hens as layers?

I will heavily cull the roosters for color and type traits of Silver Laced Wyandotte, then will submit any I intend to use for breeding for a DNA test to find hopefully 1 in 4 that are homozygous for the oocyanin gene. For the hens, I will cull roughly half that lay brown eggs (I sell or give them away as egg layers) hopefully leaving me with about 100 blue or tan on blue egg layers for next year. There will be a few white egg layers which I may choose to cull depending on how many pure blue egg layers I wind up with. I can leverage a white egg layer by breeding her to a homozygous blue egg rooster. In 2 generations, I can get pure blue egg layers.

If it helps to understand the costs involved, I am purchasing about $200 of feed (chick starter, laying pellets, and corn) per month and I am budgeting $1000 per year for DNA tests. This means I can DNA test about 33 birds per year. If I test 33 roosters, I should get 7 or 8 that are homozygous for the oocyanin gene. From that point forward, it is just a numbers game to select for large blue eggs, silver laced feathers, and a handful of other desirable traits. I should be able to stabilize most of the traits in 3 more generations which puts me at roughly 10 years to develop a blue egg laying Silver Laced Wyandotte. I started this project with heavy research in 2013 hatching the first eggs in early 2014.

Were did you came up with the 1/16th chance? i am genuinely curious.

I counted the number of blue egg layers in 31 hens hatched last year. There are exactly 2. I have more hens hatched last year that are just starting to lay. One lays a white egg, another lays a white egg with slight pink bloom.

 

[The Kooky Kiwi]

....I'll submit any I intend to use for breeding for a DNA test ...

Yes I expect that will greatly simplify matters!
I think my other half would have serious words with me if I spent that much on my chickens

 

[nicalandia]

I will heavily cull the roosters for color and type traits of Silver Laced Wyandotte, then will submit any I intend to use for breeding for a DNA test to find hopefully 1 in 4 that are homozygous for the oocyanin gene. For the hens, I will cull roughly half that lay brown eggs (I sell or give them away as egg layers) hopefully leaving me with about 100 blue or tan on blue egg layers for next year. There will be a few white egg layers which I may choose to cull depending on how many pure blue egg layers I wind up with. I can leverage a white egg layer by breeding her to a homozygous blue egg rooster. In 2 generations, I can get pure blue egg layers.

If it helps to understand the costs involved, I am purchasing about $200 of feed (chick starter, laying pellets, and corn) per month and I am budgeting $1000 per year for DNA tests. This means I can DNA test about 33 birds per year. If I test 33 roosters, I should get 7 or 8 that are homozygous for the oocyanin gene. From that point forward, it is just a numbers game to select for large blue eggs, silver laced feathers, and a handful of other desirable traits. I should be able to stabilize most of the traits in 3 more generations which puts me at roughly 10 years to develop a blue egg laying Silver Laced Wyandotte. I started this project with heavy research in 2013 hatching the first eggs in early 2014.

I counted the number of blue egg layers in 31 hens hatched last year. There are exactly 2. I have more hens hatched last year that are just starting to lay. One lays a white egg, another lays a white egg with slight pink bloom.

Impressive, thats a very large and expensive project you have there, seems to be very well planned and a very good goal, what breed did you use to source the Oocyan mutation?

 

[DarJones]

Keith Bramwell at UARK developed a line of straight comb Brown Leghorns that laid blue eggs. He provided me with 90 eggs in early 2014. I got chicks from Jerry Foley to bring in the Silver Laced Wyandotte genetics, I went back to Jerry Foley in 2017 to get a few more chicks for backcrosses. This complicated the genetics from the perspective that the traits lean heavily toward Wyandotte phenotype. I had to put extra effort into re-selecting each year for blue egg layers. I got lucky 3 years ago in using a rooster that was homozygous for blue eggs. That gave me a huge boost in number of blue egg layers the next year which meant a lot of chicks to select from. One hen in particular from that round was rose comb with very good SLW colors. She laid blue (not tan/blue) eggs.

Since Wyandottes are rose comb and I wanted to preserve the rose comb attribute, I had to have straight comb blue egg layers to produce the desired final result. Pea comb would have left me with 10 more years of breeding to break the pea comb/oocyanin linkage. I still have a lot of work to do to stabilize the traits. DNA tests will simplify things immensely.

I have to say that this has been very interesting. You know how Wyandottes have these huge poofy/fluffy tail feathers? Well, I have 2 or 3 hens that have SLW colors but have hard straight tail feathers like a leghorn. It is almost a genetic joke to see the combination.

 

[The Kooky Kiwi]

...10 more years of breeding to break the pea comb/oocyanin linkage...

@DarJones Just picking one wee aspect of your comment there - For my own learning please So how close is that Pea Comb / Oocyanin linkage?

Going back to the OP's original scenario - if she takes an F1 Easter Egger roo and breeds with it - and she desires to keep the blue egg laying genes - how "reliable" would it be for her to keep the pea combed progeny with the expectation that those are more likely to also have the blue egg gene?

Just bearing in mind that not everyone can send away for DNA tests - so any little tricks or hints for selection are useful

 

[The Moonshiner]

@DarJones Just picking one wee aspect of your comment there - For my own learning please So how close is that Pea Comb / Oocyanin linkage?

Going back to the OP's original scenario - if she takes an F1 Easter Egger roo and breeds with it - and she desires to keep the blue egg laying genes - how "reliable" would it be for her to keep the pea combed progeny with the expectation that those are more likely to also have the blue egg gene?

Just bearing in mind that not everyone can send away for DNA tests - so any little tricks or hints for selection are useful

@nicalandia
What was it? 94%, 96% that they would?

 

[DarJones]

The best information I have says the oocyanin gene is located about 80 centimorgans up from the allele that controls pea comb/straight comb. From work I've done with plants, a crossover occurs about 3 times per 1000 when the genetic distance is 80 centimorgans. I can't say that this is applicable to chickens, but it is a good starting point. If you read up on the history of the Whiting Blues, he was able to find a crossover and develop a straight comb version. I don't think the straight comb birds have been released.

One of my goals with the DNA tests is to nail down the pea comb allele location on chromosome 1. It is a separate project from the blue egg tests. Said another way, we could use a good test that could differentiate straight comb from pea comb on chromosome 1 and could ID the rose comb inversion on chromosome 7. It should be relatively simple to set up a DNA chip to detect rose comb, pea comb, straight comb, and blue egg.

One of the aspects of pea comb that causes problems is that it is dominant over straight comb. You can still usually tell that a bird is homozygous pea comb by the size and structure of the comb. Given the low crossover rate, always breeding from pea comb birds is one way to select for blue egg layers. Unfortunately, if you want rose comb - as i do - you have to breed away from pea comb. This is because combining the rose comb inversion with pea comb results in a walnut comb, not a rose comb.

There is a third allele of the same gene that controls straight and pea comb. It causes an inverted tip on the comb looking somewhat like a short walnut comb. I have not looked up cushion comb to see if it also is an allele. This is just speculation on my part, but given the location on chromosome 1, there is a very high probability of several more mutations affecting the straight comb gene.

 

[The Kooky Kiwi]

... Given the low crossover rate, always breeding from pea comb birds is one way to select for blue egg layers. ...

@TheOddOneOut

There we have it... this might be a useful tidbit for you for your future breeding!

If your original blue egg layer was an Araucana (which typically have Pea Combs) then as that Pea Comb trait is inherited by the future generations there is a HIGH likelihood the blue egg gene will also have been inherited.

It's not 100% foolproof but it's better than a complete guess So you can select young birds very very early that have the Pea combs and that have a colour/type that's pleasing to you and there's a better than average likelihood they will have that blue egg gene you are wanting to keep