Bielefelder X Cream Legbar autosexing?

[Farmers Chicken Farm]

I keep reading how autosexing is not guaranteed when you cross breed; but both these breeds are sexed by light/ dark chipmunk down color on hatch, so can one identify chicks by gender the same way on hatch?

I'm sure I'm not the only one who's though of this.

I'm certain someone out there has both these breeds and tried it already.

It seems like the perfect recipe for an autosexing green egger.

 

[Lady of McCamley]

It should work as both breeds (to my understanding) are based on double barred male on wild type (brown partridge) and single barred female on wild type (brown partridge).

Crossbreeding doesn't always work when you mix up the genetics on the barring or the red/silver, etc.

I'll link a good article from Scratch Cradle that discusses making autosexed brown partridge types...but that's using a single barred female and a brown male as base, back breeding and culling until you get to double barred male (that causes the white head dot and lighter chipmunk) and single barred female (no head dot and darker chipmunk). You don't have to start at the base and work to it. You *should* have already double barred males and single barred females from both those breeds if they are pure.

My thoughts,
LofMc

https://scratchcradle.wordpress.com/2012/08/26/gms9-autosexing-recipe/

 

[Lady of McCamley]

Do take note that while the autosexing should work just fine, as long as you are careful to keep only double barred males and single barred females, you'll need to follow your genetics for the egg color.

Your first generation 100% Bielefelder v Cream Legbar should be a green egg color, likely light green as Bielefelder egg color tends to be a pale brown with pink undertones. However, how you breed forward will take some focus on who you breed and to whom.

Brown is carried by about 13 genes. It causes a hemoglobin wash to coat the egg shell. Brown wash over white shell creates brown, varying tones. How dark a brown depends on how many of those genes your next generation captures. We who like to breed olive will refresh our lines with a renewal of a pure brown line bird (preferably the rooster) to keep those genes from breeding out. You're not dealing with dark brown, but a light brown. I find brown does breed out after about 3 or so generations, but never completely. It took me about 3 to 4 generations to get back to a truer blue in my olive egger Barnevelder/Cream Legbar line. The brown genes tended to stay, but I got few true blue layers.

Your blue is carried by the oocyean gene that puts bile back into the calcite gland so that the actual shell is colored blue. Crack open a brown egg, you will see white shell. Crack open a blue egg, and you see blue shell inside as well as outside. It only takes 1 gene to cause blue shell of the 2 gene slot possibility (it is dominate). Now the fun is breeding a brown line to a blue line...crack open a green egg, and you see blue shell, as brown wash (varying tones) over blue shell creates green (varying tones depending on how deep the brown wash).

Your first generation of B/CL will have 1 blue gene with whatever brown genes carried forward to produce shades of light to possibly middle green. But those daughters (and sons) will only have 1 blue gene. If those daughters are bred back to the Bielefelder, you will produce 50% blue shell carriers (1 gene) and 50% no blue shell carriers (no blue gene) for tones of brown. As you can see on that original B/CL line you could on breed backs of breed backs to Bielefelder eventually lose your green/blue coloring fairly quickly as the blue genes continue to drop out 50/50 of each population. So you'll want to pay attention to breeding so that you keep your blues.

Take a B/CL daughter with good green color and breed back to a pure CL rooster, you will get 50% two blue shell gene progeny and 50% single blue shell gene progeny...all blue/green layers with confidence.

If you continue to breed back to CL, you gradually lose (but not altogether lose) the brown shades and will have progeny (my experience about 3 to 4 generations) that approximate the original CL blue color.

So you'll likely want to alternate watching blue and brown with your lines to keep good coloring. I should think as long as you are careful to only keep double barred males and single barred females, the autosexing should work well each generation (with an occasional singularity).

More thoughts.
LofMc