Creating a sex-linked hybrid RIR

[noplacebo]

Hey all,
I am about to start breeding my RIR hens with my ISA-brown roo and I am hoping to produce some good dual purpose birds from the cross. I believe the ISA-Brown is a sex-linked RIR x, and the hobbyist in me wants to try and produce my own sex-linked RIR hybrids?

Is it possible to select a light roo from the second generation to cross with the RIR hens to get this effect and still produce a decent dual purpose bird?

Will i get "hybrid vigour" from crossing the RIR and the ISA-Brown if the IB comes from 50% RIR genetics?


Since this is my partners bird and she has decided he will be breeding this season, I'd like to know what the offspring will look like: differences in colours in male/female and range of colour. I'm hoping to get some dark red chicks. It's highly likely she will become attached to at least a few of the offspring so i'd love to know if they have any potential for future breeding.

thank!

chris

(does not need any more "pet" roosters)

 

[Sonoran Silkies]

2nd generation crosses of a sex-link do not re-create the sex-link. That is because the males are split for the gene; in this case Ss rather than the ss you would need to have sex-linked offspring.

Ss X S will give you SS, sS, S- & s- offspring. The only thing you won't get is males pure for gold.

 

[countrybum]

I am in the process of building a separate area just so I can cross my Roos with different hens and find out if I can get a duel purpose bird also. I do not want one like the Cornish cross that grows so fast it can barely support itself. I want one that grows at a reasonable rate, but can also be a pet if wanted. I also want it to be a good egg layer and lay through the winter.

Good luck.

 

[Krys109uk]

I think the OP intends breeding his ISA Brown male to RIR hens.

So first generation S/s+ X s+/- = S/s+ & s+/s+ males; S/- & s+/- females

To get sex links in the second generation there would be s+/s+ males to put over S/- females.

(Looks like dominant white is also in there....which is presumably how the silver RIwhite gets a white tail?).

 

[noplacebo]

I was thinking the second generation of offspring.. so the grandchildren. Excuse my poor grasp of chicken genetics, but if it's mainly only two genes for colour being expressed, and colour is all i'm selecting for:

Parents:
ISA Brown x RIR
Ss x SS

Produces:
Children:
SS, Ss

Selecting the Ss:
Ss x Ss

Produces:
Grandchildren:
SS, Ss, Ss, ss


I know that's a really basic way of representing what really happens (and the grandchild stuff just helps me understand) but with some selection the grandchildren (or great grandchildren) could have both dominant or both "recessive" genes?

If this is possible and I produce a white roo in the grandchildren, (ss in my example) and cross it with the original RIR hens (SS) would I get all sex linked Ss offspring?

Sonoran Silkies, you mentioned that crossing sexlinks produces everything except pure males? is this something about the way the gene is passed to the male offspring?

Thanks again for all your input!

 

[noplacebo]

Quote:
I think that answers a lot of my questions, unfortunately i'm only able to understand the basics of what you're saying. Is there a good place to learn up on this? I've been trying to get a hold of genetics of chicken colours without success.

s+ = less dominant gene?

and females only carry or display one gene?

Good eye with the white tail. I think his tail is "splash" (white with flecks of black) which seems a little remarkable. not sure how "pure" he is but he's only meant to be a hybrid.

 

[noplacebo]

On further investigation the ISA Brown is reported to be a cross between a RIR and a Rhode Island White - not the same breed. White bird, similar to the RIR, bred in the same place.

Not sure what that means for the colour genetics though.

 

[Krys109uk]

The ISA Brown sex link is using the sex linked gold (s+) & sex linked silver (S). The reason they can work is because they are positioned on the Z sex chromosome. Males have two Z chromosomes females have one Z & one w.
RIR are genetically gold; RI whites are genetically silver.
The male RIR will be carrying two gold genes; one on each of his two Z chromosomes. This is written s+/s+
The female RI white will carry one silver gene on her only Z chromosome. this is written S/- ( the - shows there is no corresponding gene on the w chromosome).

There are some other colour genes involved which may make the appearance of the offspring variable, but ought not to prevent a gold/silver sex linked cross being possible on the second generation.

When the RIR male & the RI white female are bred together all of the offspring inherit, from their father, a Z chromosome carrying a gold gene. The male offspring will also inherit a Z chromosome from their mother. The Z chromosome from the mother will be carrying the silver gene, which is dominant to the gold gene. (technically it's incompletely dominant but we don't need to go into that). So all male offspring will appear silver (usually lighter or yellow downed chicks). The female offspring will have inherited a w chromosome from their mother. They only have one Z chromosome; the one with the gold gene which they inherited from their father. Thus they will be gold (usually darker more orange downed).

So your ISA Brown male, being a male from a such a cross, will be carrying one silver gene & one gold. And you RIR females are carrying their one gold gene. Clearly a sex link will not work like this. But from the mating you will get around a half of the female chicks which will be genetically silver (the other half will be genetically gold & not work for a gold/silver sex linked cross). You will also get around half of the male offspring which will carry two gold genes; one on each of their Z chromosomes, (the other half will have a gold gene on one Z chromosome & a silver gene on the other chromosome & will not work for a gold/silver sex linked cross)

 

[blackdotte]

One fly in the ointment, ISA Brown male chicks are usually culled at birth, however those that survive do not look like your cockerel. They are a Pyle pattern, white with a bit of red on the neck hackles & shoulders.
Yours looks more like a RIR X White Leghorn. White Leghorns are basically a black or barred ,silver based bird so you could get all sorts.
David

 

[Krys109uk]

Yours looks more like a RIR X White Leghorn. White Leghorns are basically a black or barred ,silver based bird so you could get all sorts.

Wouldn't a straight RIR X White Leghorn give all white offspring?​