Understanding ZSB Z+, ZS ZB, ZSB ZS, ZSB ZB and ZSB ZSB

[Pinoy Angelfish]

There is an autosexing chicken breed that i'd like to copy but not as a breed, just a hybrid that will autosex and it is the Polbar. From reading about it, the Z chromosome was described as having both silver and barred genes in a single chromosome. Before this, i only knew of ZS and ZB.

Would a ZSB Z+ and ZS ZB look the same? My guess is that they will look the same/similar. To differentiate them i'd like to call the ZSB double linked silver barred.

This rooster below is from a Rhode Island Red roo over a Dekalb white hen. I just recently bought him, shipped in a box and upon opening i got surprised because he is barred (Thank You Father God Lord Jesus). I asked the seller if the other male sibs were also barred and yes they are all barred as well. This means that their mom was barred and being white it was not obvious.

Since he also appears to be silver then the mom could only be ZSB. This roo is double sex linked silver barred ZSB Z+ not ZS ZB. Having the same ZSB as that in the Polbar he will be used for the autosexing project instead of a Plymouth Barred Rock.

Using the Punnett square for predicting outcomes, there will be a difference for these different male genotypes: ZSB Z+, ZS ZB, ZSB ZS, ZSB ZB and ZSB ZSB. Hopefully with their phenotypes there would be slight differences discernible enough to help determine which is which.

 

[Amer]

He appears to be gold based to me.
Why are you using Z in front of SB?
His genotype would be s+/s+B/b+, or if he was actually silver S/SB/b+ or heterozygous for silver S/s+B/b+
His mom is most likely S/ZB/Z, though often people use - instead of Z.

 

[NatJ]

There is an autosexing chicken breed that i'd like to copy but not as a breed, just a hybrid that will autosex and it is the Polbar. From reading about it, the Z chromosome was described as having both silver and barred genes in a single chromosome. Before this, i only knew of ZS and ZB.

Would a ZSB Z+ and ZS ZB look the same? My guess is that they will look the same/similar. To differentiate them i'd like to call the ZSB double linked silver barred.

The Z chromosome has many genes on it.
Every chicken Z chromosome has either silver or gold.
And every chicken Z chromosome has either barring or not-barred.

Barred Rocks commonly have both silver and barring, while Cream Legbars have gold and barring. Many breeds have silver and not-barred, and many breeds have gold and not-barred.

Are you familiar with linked genes and crossover rates? Barring and silver are far enough apart on the Z chromosome that crossovers happen very frequently. (Let me know if you need more explanation of that.)

 

[Amer]

The Z chromosome has many genes on it.
Every chicken Z chromosome has either silver or gold.
And every chicken Z chromosome has either barring or not-barred.

Barred Rocks commonly have both silver and barring, while Cream Legbars have gold and barring. Many breeds have silver and not-barred, and many breeds have gold and not-barred.

Are you familiar with linked genes and crossover rates? Barring and silver are far enough apart on the Z chromosome that crossovers happen very frequently. (Let me know if you need more explanation of that.)

I know what the z chromosome is but don’t know why it’s in the front of a genotype, people use it like SZBZ but not ZSB.

 

[Pinoy Angelfish]

From https://www.backyardchickens.com/th...n-x-rir-look-like.628515/page-3#post-25044923
"But you are not taking into account the frequent crossing over at meiosis and since Silver and Barring are not linked to each other they will segregate independently.

Female offspring of those double sex linked males could be ZBs+/- and Zb+S/- and ZBS/- "
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The above is nicalandia's reply in another thread which i moved here.

Hi nic, yes they do recombine but at times also they stay/go together as you have shown in your statemenet above ZBS/ . and i see you've also used the term "double sex linked" in your statement above

I don't know if you are using the term in the same way as i am, but im using the term "double sex linked barred silver" specifically to describe the ZBS combination in relation to developing an auto-sexing chicken "breed"- a hybrid will do for me; similar to the Polbar.

Quoting from: https://www.european-poultry-scienc...-hatching,QUlEPTQ1OTk5NjcmTUlEPTE2MTAxNA.html about the Polbar chicken breed, third paragraph of the introduction:

"It was found that homozygous silver barred breed (♂ZBSZBS; ♀ZBSW) can be obtained using appropriate crossing "

What amazes me with this Polbar chicken breed is that not only is the breed auto-sexing but also the hen can be used for both black sex link and red sex link crosses and this is because the Polbar hen is double sex linked barred silver ZBS.

The same goes with the Plymouth Barred Rock and the Delaware, they are also chicken breeds that are double sex linked barred silver. The Delaware though is not auto-sexing like the Plymouth Barred Rock and the Polbar. The Plymouth Barred Rock only works with black sex link crosses unlike the Polbar...

So to me, the naming convention double sex linked barred silver for ZBS, has a special meaning.

 

[NatJ]

The above is nicalandia's reply in another thread which i moved here.

I hadn't noticed that thread.

I see now that you are saying things in a way I'm not used to, but you are working with the same ideas I'm familiar with.

Would a ZSB Z+ and ZS ZB look the same? My guess is that they will look the same/similar. To differentiate them i'd like to call the ZSB double linked silver barred.

If the rooster is heterozygous for gold/silver and also for barred/not barred, I do not think there is any way to distinguish which genes are on which of his two Z chromosomes.

And since barring and silver have been found to segregate independently, it should not matter. You should be able to get daughters in all combinations, in equal numbers (gold/barred, silver/barred, gold/not-barred, silver/not-barred), and the sons as well.

 

[nicalandia]

What amazes me with this Polbar chicken breed is that not only is the breed auto-sexing but also the hen can be used for both black sex link and red sex link crosses and this is because the Polbar hen is double sex linked barred silver ZBS.

The same goes with the Plymouth Barred Rock and the Delaware, they are also chicken breeds that are double sex linked barred silver. The Delaware though is not auto-sexing like the Plymouth Barred Rock and the Polbar. The Plymouth Barred Rock only works with black sex link crosses unlike the Polbar...

Not only that, the Polbar hens are actually Triple-Sex linked as they are sex linked Id(Dermal Inhibitor turns dark shanks to light shanks) if crossed with a dark shanked male the females will be dark shanked and males light shanks. If crossed with dark skin Silkies the females will have black skin and males will have light skin.

Edit. Just wanted to point out that the ZBId is actually the closest to being a True doubled Sex-Linked trait as they are closely linked and don't segregate independently from each other with a 10% chance of crossing over(Sex linked Barring
was shown to be 13.7
cM from inhibitor of dermal melanin on the long
arm of Chromosome Z )

Also Sex linked Silver and Sex linked Slow Feathering are closely linked in Barred Rocks and is a very tight linkage(can't remember how close they are)