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- #41
Baphometpwnsyou
Chirping
- Nov 23, 2019
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Or is that level simply pushing the breeding thing to far?
Help breeding!?
- Thread starter Baphometpwnsyou
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The gene for rose combs is not sex-linked.
You could hatch many more chickens than needed, then cull the ones of each gender with the "wrong" comb.
But you won't be able to get them breeding true for gender-specific comb types.
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- #43
Baphometpwnsyou
Chirping
- Nov 23, 2019
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What traits are sex linked?
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- #44
Baphometpwnsyou
Chirping
- Nov 23, 2019
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And dang this one is gonna be a tough one to do considering the three slw that I have currently two of them started all gray with white down there backs and the third one started as an all black type of color?
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- #45
Baphometpwnsyou
Chirping
- Nov 23, 2019
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But yeaa I’m pretty sure they’re all gonna end up being hens! As of right now anyway lol
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- #46
Baphometpwnsyou
Chirping
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“ It is also important to note that the offspring of a sex-linked cross cannot themselves be used in a second sex-linked cross.” So that means that it would mean nothing to have them with any sex link traits right?
--Silver/gold (Silver is dominant)
--Chocolate (not-chocolate is dominant, chocolate is recessive)
--dark skin (Light skin is dominant, dark skin is recessive)
(note, this is just one specific dark skin gene--Ayam Cemani have a bunch of other genes involved too.)
--slow feathering (Slow feathering is dominant, fast feathering is recessive.)
--Barring (incompletely dominant: one copy makes white bars, two copies makes more white bars)
(Sex-linked means they are on the sex chromosomes, but they can still appear in chickens of either gender. For some examples, look at Gold Laced Wyandottes and Silver Laced Wyandottes, or Barred Rocks and Black Australorps and Chocolate Orpingtons.)
Last edited:
Um, this is quite long, but you did ask... 
Sex-linked genes are on the sex chromosomes.
Humans have X and Y for sex chromosomes, but chickens have Z and W.
The male chickens have two Z chromosomes. The females have one Z chromosome and one W chromosome.
Because the female has only one Z chromosome, it does not matter whether the gene is dominant or recessive: she shows that gene. So a hen is either gold or silver, chocolate or not-chocolate, etc.
Because the male has two Z chromosomes, he can be pure for one trait (both genes match), or he can show the dominant trait but also show the recessive trait (silver carrying gold, not-chocolate carrying chocolate.)
Sexlinks are done by a clever trick that works because females have one Z chromosome and males have two.
With silver/gold, it works like this:
The father has two copies of the recessive gene (gold) while the mother has the dominant gene (silver.)
The daughters get their Z chromosome only from their father, so they only have the recessive gene (gold.)
The sons get one Z chromosome from each parent, so they get the recessive (gold) from their mother, and the dominant (silver) from their father. They look silver, because it's the dominant gene.
So the daughters are gold, the sons are silver, and you can tell their gender when they hatch.
But if you cross those sexlink chicks, the trick doesn't work. The cockerels have one dominant and one recessive gene, and they can pass either one to any chick. And the pullets have the recessive gold gene, which is also not what you need.
The same trick works with barred/not barred.
Father and daughters are not-barred.
Mother and sons are barred (sons carrying not-barred.)
It also works with chocolate, or with slow-feathering. (Dark skin would theoretically work, but it is not always possible to tell the skin color at hatch, so it's not commonly used.)
Barring is different than the other sex-linked genes because birds with two copies of the barring gene have more white than birds with one copy. So it can be used to create "autosexing" breeds.
Autosexing ONLY works with the barring gene.
It works because you can tell which birds have one copy of barring (females, dark-barred) and which have two copies (males, light-barred.)
It's in Barred Rocks, Dominiques, Cream Legbars, Bielefelders, and a number of other breeds.
The autosexing breeds do breed true: you breed the double-barred (light) males to the single-barred (dark) females, and you get double-barred (light) males and single-barred (dark) females. The same pattern holds true in every generation.
To reliably sex the barred birds at hatch they apparently need some other modifiers too, which are not fully understood. So some lines of Barred Rocks can be sexed by the color & markings of the chick down, and some cannot. The same goes for Cream Legbars, and any other autosexing breed. The adults are easy to distinguish, the chicks are also pretty easy once they grow feathers, but the chick down is not always different between the sexes.
So barring can be very useful, but unfortunately I don't really think you want Ayam Cemanis with white bars on them
Sex-linked genes are on the sex chromosomes.
Humans have X and Y for sex chromosomes, but chickens have Z and W.
The male chickens have two Z chromosomes. The females have one Z chromosome and one W chromosome.
Because the female has only one Z chromosome, it does not matter whether the gene is dominant or recessive: she shows that gene. So a hen is either gold or silver, chocolate or not-chocolate, etc.
Because the male has two Z chromosomes, he can be pure for one trait (both genes match), or he can show the dominant trait but also show the recessive trait (silver carrying gold, not-chocolate carrying chocolate.)
Sexlinks are done by a clever trick that works because females have one Z chromosome and males have two.
With silver/gold, it works like this:
The father has two copies of the recessive gene (gold) while the mother has the dominant gene (silver.)
The daughters get their Z chromosome only from their father, so they only have the recessive gene (gold.)
The sons get one Z chromosome from each parent, so they get the recessive (gold) from their mother, and the dominant (silver) from their father. They look silver, because it's the dominant gene.
So the daughters are gold, the sons are silver, and you can tell their gender when they hatch.
But if you cross those sexlink chicks, the trick doesn't work. The cockerels have one dominant and one recessive gene, and they can pass either one to any chick. And the pullets have the recessive gold gene, which is also not what you need.
The same trick works with barred/not barred.
Father and daughters are not-barred.
Mother and sons are barred (sons carrying not-barred.)
It also works with chocolate, or with slow-feathering. (Dark skin would theoretically work, but it is not always possible to tell the skin color at hatch, so it's not commonly used.)
Barring is different than the other sex-linked genes because birds with two copies of the barring gene have more white than birds with one copy. So it can be used to create "autosexing" breeds.
Autosexing ONLY works with the barring gene.
It works because you can tell which birds have one copy of barring (females, dark-barred) and which have two copies (males, light-barred.)
It's in Barred Rocks, Dominiques, Cream Legbars, Bielefelders, and a number of other breeds.
The autosexing breeds do breed true: you breed the double-barred (light) males to the single-barred (dark) females, and you get double-barred (light) males and single-barred (dark) females. The same pattern holds true in every generation.
To reliably sex the barred birds at hatch they apparently need some other modifiers too, which are not fully understood. So some lines of Barred Rocks can be sexed by the color & markings of the chick down, and some cannot. The same goes for Cream Legbars, and any other autosexing breed. The adults are easy to distinguish, the chicks are also pretty easy once they grow feathers, but the chick down is not always different between the sexes.
So barring can be very useful, but unfortunately I don't really think you want Ayam Cemanis with white bars on them
Almost 20 years ago, I started learning about chicken genetics on the internet. There's a lot I don't know, and I keep forgetting things and having to re-learn them, but some parts have managed to stick in my head
I have a special interest in sex-linked genes and in comb types, so I feel that I understand those bits fairly well by now.
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