Pea and Cushion Combs, Genetics Behind Them?

Hi all. I am wondering the genetics behind the pea and cushion combs. I am in new Zealand, and in the process of gathering a breeding flock of Araucanas(Very similar to the Ameraucana, but called araucana here in nz) and have a good rooster, have had great feedback on hm from several breeders and judges. However, he has a cushion comb, not a true pea comb. Points are not docked for a cushion comb here as they are very common, but i would like to breed true pea combs in the future, as that is what our standard calls for.
I am looking at buying a couple of nice black pullets with pea combs if i can sort the transport.
How long may it take to establish good pea combs if i succed in getting these pullets?
I am wanting to know the genetics behind the pea and cushion cobs so i can figure out how to breed for pea combs, and what i should be looking at doing ect

I'm still introducing myself to chicken genetics, so please don't get too technical on me.

How do each work, how dominant are they? What problems may i encounter? How long might it take to establish good pea combs in my flock, if i succeed in getting these pullets? Will it take a couple of generations for the pea comb to show over the cushion?

Cheers

I have to get a little technical to explain this. I’ll have to use symbols too.

The basics are that you have two genes that determine basic comb type, pea and rose. Nothing is simple in chicken genetics but consider pea and rose genes are both dominant. That means that even if just one of these genes is present, you can see the effects. There are two genes at each gene pair. This complicates it more.

Unfortunately for your question, I think I have to add this. The rose comb gene is totally dominant. It will act the same whether you have one copy or two at that gene pair. But the Pea comb gene is only partially dominant. If you have two Pea genes at that gene pair, you get the full effects. But if you have one Pea and one not-Pea, it is only partially dominant. You’ll still see the effects, but it will not look like a pure Pea comb. Since your chickens appear to be show chickens, I would expect they will be pure for that Pea gene and you won’t have this additional complication to deal with.

For symbols, consider upper case R to be the dominant rose gene and lower case r to be the non-dominant not-rose gene. Same for the pea comb, upper case P is dominant pea and loser case p is non-dominant not-pea.

If you have a dominant Pea comb and no rose comb gene, you get a Pea comb.
P,P + r,r or
P,p +r,r

If you have a dominant Rose comb and no pea comb gene, you have a Rose comb.
p,p + R,R or
p,p + R,r

If you have both a Pea and a Rose, you have a Walnut or Cushion comb.
P, P + R,R
P,p + R,R
P,P + R,r or
P,p + R,r

If you have no Pea and no Rose you get a Single comb.
p,p + r,r

You can get a whole lot more types of combs than just Pea, Rose, Cushion, and Single. That’s because there are several different modifiers that can change the appearance. For example, the Walnut and Cushion have the same basic genetics but the Cushion has a modifier that smoothes out the Walnut and turns it into a Cushion.

I don’t know if your rooster has one copy of the rose comb gene or two copies. That will determine how many generations it takes to get rid of the Rose gene. The good news is that since the Rose is dominant and you will always see an effect, it is pretty easy to get rid of. As complicated as all this may sound, your problem is pretty simple.

If your rooster is pure for Rose, which I expect it would be, and if your hens are pure for Pea, which I expect they would be, cross your rooster with your hens. Your rooster will be P,P + R,R and your hens will be P,P + r,r. That means the offspring will be P,P + R,r.

Now cross one of these roosters back to your original hens. Half the offspring will be Cushion comb and half will be Pea comb. Select your breeders from the Pea combed chickens and you are where you want to be.

There are other possible starting points but this is getting too long. You’ll have to figure them out.

I do not know what effect that modifier gene that smoothes the walnut into a cushion might have on a pure pea comb. I also don’t know if it is dominant or recessive. It may have no effect or you may get some weird looking pea combs. You’ll just have to play that part by ear.

I hope I kept my upper and lower case straight through all that. Good luck with it.

Thanks, that was really helpfull. I was able to follow most of it too, yay

A walnut comb, being the variation on a cushion, does that look like a cushion with flat/rounded ridges/waves? Or is that just a cushion comb? My boy has a good flat one, but have seen a few birds with textured cushion combs, and couldn't figure out if they were a cushion or something else.

Yes, the two pullets with pea combs i am looking at come from show lines. Rooster comes from good breeding lines, but unsure how strictly the breed to the standard. However, going by the feedback i have had about him, his only faults are the cushion comb and he has a bit of white at the base of his tail. He has a lovely full, deep body, good wide breast, good type, and lovely full beard and muffs.

I'm really looking forward to spring and seeing what kind of chicks i get from him with my hens.

I would like to get into showing a bit more, so i'm very keen to get to breeding for good pea cobs. I have been to a couple of local shows, and looking at going to a big one next month, but cushion combs are very common here, there are some good pea combs, but i don't think many people are trying to breed for them. Here most people seem to be too busy trying to breed for interesting colours. So i'm really keen on trying to establish good breeding stock so i can aim to breed to the standard.

I don't know what the Australian standards call for a cushion comb to look like. It's almost probable there are differences in yours and ours. Maybe the best way to say it is that the cushion is smooth where the walnut is rough.

This thread has several photos of walnut combs. Maybe that will help.

https://www.backyardchickens.com/t/644872/comb-contest-walnut-winner-announced

Ahh yes, some of those look like a couple i saw at the show.

And in the process of sorting transport, sent in the booking form, just waiting to hear back about the dates. Looking forward to getting my two new pullets They are from show lines, and should be good quality, as the breeder is having to downsize her breeding operation, and the araucanas are one of the breeds to go, so shes selling her entire stock. I wish i had the space to have more than one rooster atm as i'd get one from her, but sadly i don't have the space at the mo.

Once i have them it will give me a starting group of 5 hens to work with. I will check combs on the 3 i already have in the next couple of days, and see what it looks like they might have.

I think the cushion comb (that twistedfeathers mentions) in the araucanas is not linked to the rose comb??I am in New Zealand also.
I could be wrong- but I have bred quite a few araucanas with a proper pea comb to single comb bird and had these 'cushion' combs come out (along with some normal looking pea combs too). I have also seen them in so many 'purebreds' too. Has anyone got any ideas on this? could it just be some other modifier genes modifying the pea comb?

Well i have my two pullets with pea combs now, also managed to get my hands on a hen with a pea comb. Have some of their eggs in the incubator, so it will be interesting to see what i get comb wise from them crossed with my roo who has cushion comb.

And yes nzchickie, i wonder about it too, as the cushion comb seems to be dominant, with so many of them around.
I have a wee easter egger pullet too, and she looks to have a modified pea comb, not a fantastic one as it's a bit ways, but looks to be a single row of peas. I have hatched 6 eggs from her and it will also be interesting to see what her offspring develop for combs. At this stage they all look to have tiny rows of bumps, so here's to hoping for some pea combs, as that will give me an idea of the genetics behind my boys cushion.
This photo was taken two months ago, and shows what my boys comb looks like. Going to be very interesting to see what i get from him and pea combed hens

Yes it will be interesting to see what you get! I first saw these combs on a batch of chicks I brought, never saw parents so don't know if the araucana used had a pea comb or 'cushion' type comb- They were araucana x Orpington, they all matched the perfect cross description, no other features where wrong or missing, out of 7 chicks, 3 had straight combs, 3 had cushion combs, and 1 had a normal pea comb with rows, so that araucana must have been split for single/pea comb,

Well the babies are growing up. They are somewhere around 6-7 weeks old i think. Silly me didn't write on the calendar when they hatched.
Have 6 babies. Will try get photos up later.
Comb wise, 2 have cushion combs, 3 look to have pea combs, and one little roo either has a tall, skinny pea comb, or someone is carrying a straight comb that has popped up. If it is a straight comb, i'd say the hen is carrying it, as we have no idea who her father was, or even grandfather, but comb wise would be either rose or straight.

Will be interesting to see how the baby's comb develop as they get older, and what they look like at maturity

TwistedFeathers said:

Well the babies are growing up. They are somewhere around 6-7 weeks old i think. Silly me didn't write on the calendar when they hatched.
Have 6 babies. Will try get photos up later.
Comb wise, 2 have cushion combs, 3 look to have pea combs, and one little roo either has a tall, skinny pea comb, or someone is carrying a straight comb that has popped up. If it is a straight comb, i'd say the hen is carrying it, as we have no idea who her father was, or even grandfather, but comb wise would be either rose or straight.

Will be interesting to see how the baby's comb develop as they get older, and what they look like at maturity

Click to expand...

TwistedFeathers, I would be interested to see pictures of your birds' combs and the comb differences at this stage of their growth, if you have any.