Is it true

[RAREROO]

Quote:
Delawares are more predictable, they are Barred Silver Columbian so a Black Australorp roo on Delaware hens should be a great cross actually, this would give you sexlinked offspring the females would be black and the males would be barred.

A Delaware roo on Black Australorp hens would give you all Barred chicks.

 

[Sonoran Silkies]

There are three genes that turn OFF the expression of colour in a feather (which is what a white feather is: no pigment).

Dominant white, recessive white and silver. They each work differently.

Chickens have two pigments in their plumage: red and black. Recessive white covers both (but requires two copies of the gene), dominant white covers black when one gene is present, and also red if a second gene is present. Silver replaces sex-linked red/gold, but has little affect on autosomal red.

Recessive white only works if two copies are present; it is not very leaky, meaning that the bird will be totally white, with possibly a stray coloured feather or two.

Dominant white prevents black pigment if present in one copy. Two copies will also turn off red.

 

[Ridgerunner]

Thanks, Sonoran. That is a clear, simple description. I appreciate both clear and simple.

The way I understand that red sex link works is gold in the rooster and silver in the hen, but the recessive white has to be where it won't pair up in the offspring. If the chick is cc, it is going to be totally white, whether male or female. It needs to be either CC or Cc. So cc in one of the parents with CC in the other would work. You probably would not know it if the rooster was the cc one since it would be white, but theoretically it would work. I can be totally wrong. That's why I'm putting this out here, so I can maybe learn something.

So a white rock hen with double recessive white and the silver gene can make sex links. But it has to have silver (not sure all of them do) and the rooster cannot be Cc.

The dominant white (with CC) is not clear to me. I think the hen needs to be I*I* and the rooster ii (no dominant white) for it to work. If either is split, then either sex can wind up I*i. The different I*'s seem to effect pattern color. Or maybe it is that Silver needs to be present for down color more than final plumage color so as long as one I* is present the down is yellow? If both are split, then some offspring can wind up ii so it will not work.

Black sex links seem more straight forward. If the hen is barred and the rooster is not, the male chicks will be barred and the females will not. The complicating factor here is that the other colors in the parents have to allow the barring to be seen at hatch. While it may be a sex linked trait in the adult plumage, the barring doesn't do you a lot of good to separate the chicks if you can't see it at hatch.

The more I learn, the less I know.

 

[Sonoran Silkies]

Sex-linking requires no white. It does require that the female have the dominant allele of a sex-linked gene and that the male be pure for the recessive allele of that same gene, and the gene's expression should be obvious at time of hatching. The most common gene used for creating sex-linked birds is silver: S/- hen and s+/s+ cock.

Ideally you do NOT want either one to carry recessive or dominant white, which can mask the silver or gold. If both parents carry a single allele of recessive white, you will have some white offspring. If either is pure for recessive white, you cannot tell whether the bird is silver or gold.

Likewise if a hen carries dominant white (either one or two copies) and silver (I/? S/-), you cannot differentiate it from one that has two copies of dominant white and gold. (I/I s+/-). One copy of dominant white inhibits the expression of black pigment; a second copy inhibits the expression of red pigment. However, silver also expresses the expression of sex-linked red pigment.


With black sex-linking, the hen must be barred and the cock not-barred. Once again, you do not want white, for similar reasons. If either carry a copy of recessive white, some of the offspring will be white. If the mother carries dominant white, you cannot tell whether she is barred or not. If the father carries dominant white, you cannot determine that he is not-barred.

For barred chicks, the size of the head spot can differentiate between a bird that has one copy (females and het. males) and those that have two copies (males). With a sex-linked cross, none of the females should have any barring, and thus will not have a head spot; if they do, the father carried a copy of barring. The males in a sex-linked cross should have ONE copy of barring, inherited from the mother.

https://www.backyardchickens.com/forum/viewtopic.php?id=261208 goes into a lot of detail about sex linking, and is pretty easy to understand. Lots of chick photos that depict male vs female, too.