removing steel genetics

[ladysown]

So I bought in some unpedigreed dutch.

SOMEONE has the steel gene in them, either the buck, or a senior doe but I'm not sure who.

How do I track it down and remove it from the gene pool means what? Culling everything that could possibly carry it or just the rabbits that show it and not breeding from them? Would it be that simple to simply cull the rabbits that show it?

I've never tried to eradicate a colour before so I'm a bit uncertain how to proceed. I have two additional litters from the buck so hopefully that will tell me something...

 

[Alaska Satin]

So I bought in some unpedigreed dutch.

SOMEONE has the steel gene in them, either the buck, or a senior doe but I'm not sure who.

How do I track it down and remove it from the gene pool means what? Culling everything that could possibly carry it or just the rabbits that show it and not breeding from them? Would it be that simple to simply cull the rabbits that show it?

I've never tried to eradicate a colour before so I'm a bit uncertain how to proceed. I have two additional litters from the buck so hopefully that will tell me something...

Steel is dominant at the E locus (to every E series allele except dominant black <E(D)> which is rare), but it can hide effectively in at least two ways:

- if it's homozygous <E(S)E(S)> aka a "supersteel" which can look like a self black (or a self blue, chocolate or lilac)
- if it's in a self rabbit <aa>, which does not allow the steel banding to be expressed

Steel expresses itself in the phenotype as steel only in the presence of agouti <A_>. It also shows itself, more subtly, in otters/martens a(t)_>.

You don't say what your new Dutch varieties are, but the most likely suspects would be black, blue, chocolate or tort, since those are all selfs, which will hide steel. Alternatively, any rabbit that looks like one of those self varieties may actually be a supersteel. Supersteels can easily appear in Dutch stock because steel is an accepted variety in Dutch, and if you breed steels with each other, you'll get supersteels. And as soon as you start crossing steels or supersteels with self varieties, you'll get selfs that hide the steel, whether the rabbit has one or two copies of the steel allele. The remedy will lie in the gray, chinchilla, or golden yellow Dutch, all of which are agoutis. (Golden yellow, being a non-extension variety, might present problems if the suspected steel also carries non-extension, but even with non-extension, steel can show...but that's a whole other discussion!)

So to eliminate steel, breed any suspect rabbit with an agouti, preferably homozygous <AA> or heterozygous with otter <Aa(t)>. If it's a normal agouti (not steeled), you'll know that particular rabbit does not carry steel itself. So, no matter what the suspected steel rabbit has at its A locus, all the bunnies will all be steels or steeled otters, since every kit will inherit either an agouti <A> or an otter <a(t)>.

If you don't have an agouti, a homozygous otter/marten <a(t)a(t)> will also work (obviously not a purebred Dutch rabbit). A self <aa> won't help at all, while an agouti or otter rabbit carrying self <Aa> or <a(t)a> may be helpful, or it may not - it can depend on the luck of the draw if you'll get a dominant agouti or otter. But in any case, if you get a single steel or steeled otter, you'll confirm your suspicion.

I'm sure you already know what a steel looks like, but not as many people know what a steeled otter looks like. It certainly perplexed me when I got my first out of what I thought was a self black x self black pairing, and we called it a "tweener" since it looked like it had vestigial otter markings. As it turned out, one of the "self blacks" was a supersteel which was heterzygous for otter and self <a(t)a>; the otter could not be expressed due to the double steel alleles <E(S)E(S)>. All of the kits got a steel <E(S)>courtesy of the supersteel parent, but while some of the kits looked like self blacks <aa....E(S)_>, others inherited the otter allele <a(t)A...E(S)_> and were "tweeners." Here is one of the "tweeners" we got, which looked like a self black on top, but had minimal otter markings underneath:


So it was a mess for a while, but once we figured it out, it's not hard to manage. There's still steel lurking in my Satins, but I'm beginning to think that there's a silver, or rather black, lining as long as I keep them away from my agoutis and otters. Steel <E(S)> is featured in some Silver Fox (which are selfs) due to its effect on the undercolor; some SF breeders believe it causes the undercolor to be deeper/darker. I have only started looking at that, but now that I've identified where the steel came from originally - at least six generations back - it begins to seem to me that my self blacks that carry the steel allele may very well be my best-colored blacks. So, it may not be something you necessarily want to eliminate!

 

[MsTemeraire]

Steel is very very common in Dutch where I am (UK). Most selfs are, in fact, masked steels. If you truly want to eliminate it, go for a Gray, Yellow (I think you call it Gold) or Tort as an outcross. Anything agouti (Gray) cannot carry Steel, likewise Tort and Gold.

 

[ladysown]

so since I like chocolate and blue I should just let them be and cull those obvious steel rabbits.

 

[Alaska Satin]

so since I like chocolate and blue I should just let them be and cull those obvious steel rabbits.

Yes, if you only breed those together, you'll never see the steel phenotype - they'll always be selfs so the steel can't show.

How did you come to think steel was lurking in your rabbits?

 

[MsTemeraire]

so since I like chocolate and blue I should just let them be and cull those obvious steel rabbits.

There must be a reason why so many Dutch mask Steel. Alaska Satin has said some of their best coloured blacks have Steel. Silver Fox have steel. New Zealands and Californians often have steel. Maybe it intensifies a self colour; perhaps it improves the undercolour. I don't think it's by accident that it's in certain breeds.

 

[ladysown]

Yes, if you only breed those together, you'll never see the steel phenotype - they'll always be selfs so the steel can't show.

How did you come to think steel was lurking in your rabbits?

i had one in a previous litter, and have four in a current litter. I'm used to seeing steel in my meat mutts... wasn't expecting in the dutch (but I don't know the parentage since they came unpedigreed).

 

[Alaska Satin]

i had one in a previous litter, and have four in a current litter. I'm used to seeing steel in my meat mutts... wasn't expecting in the dutch (but I don't know the parentage since they came unpedigreed).

What colors were the parents that gave you the steels?

There must be a reason why so many Dutch mask Steel. Alaska Satin has said some of her best coloured blacks have Steel. Silver Fox have steel. New Zealands and Californians often have steel. Maybe it intensifies a self colour.

I think the simplest explanation for why there's a lot of steel in Dutch is because it's a recognized variety here, and as soon as you cross it into your self varieties, it starts to lurk and can persist for as long as you continue to breed selfs.

The other breeds (particularly NZs and Cals) seemed a bit less self-explanatory since steel has never been recognized in those in the US. I used to figure maybe there was Flemish input at some time. But I think you're on the right track about color improvements, since both of those breeds recognize self black varieties (in Cals of course it's the only variety). From a recent @Dimplz post:

https://rabbittalk.com/threads/just-for-fun-silver-fox-and-californian-cross.26031/#post-362890
I was talking to an old timer who raised purebred SFs for 60 years. We got on the topic of the steel gene and the silvering gene in the SF lines. Here is what he told me.
"Never breed the steel out of your SF lines. The perfect genotype for the SF is EsEs and Sisi2 or sisi."
...the steel genes control the silvering genes, keeping the silvering genes in check. The silvering genes cause the dispersment of random white hairs and cause a silvery base undercoat. When the rabbit is a super steel, it darkens that base undercoat, causing a darker contrast between the black fur and the white hairs.

NZs and Cals don't need contrast between white and dark hairs, but any self rabbit can benefit from a deeper color in its undercoat. I'm now wondering if that's what giving some of my black Satins their great undercolor. Here is a broken black that I know carries steel, as she just gave me steeled otters when bred with my blue otter buck (first photo), compared to self black doe I have no reason to believe carries steel (second photo):

Maybe @reh can comment on the molecular repercussions of the steel allele, and how that might apply to the undercolor on a self rabbit?

 

[MsTemeraire]

I think the simplest explanation for why there's a lot of steel in Dutch is because it's a recognized variety here, and as soon as you cross it into your self varieties, it starts to lurk and can persist for as long as you continue to breed selfs.

It's the same here in UK; no surprise really as US got its foundation Dutch stock from the UK originally and they share a very similar breed standard. In Europe, Dutch have a much different breed standard and are larger. The prevalence of steel in self Dutch lines in UK is probably not being helped by dwindling gene pools, but now you've revealed a similar situation in the US, I wonder that they may have been that way for a very long time. Dutch fanciers in the UK are not very genetics-minded, so most are unaware of the presence of Steel. A breeder who is genetics-savvy and has both Tri-Colour Dutch (which are a separate breed here) and 'normal' Dutch alerted me to the steel basis in UK Dutch, and the reluctance of breeders to acknowledge it is so ubiquitous. She was doing some outcrossing of Tri to normal Dutch (as is often done to improve the white pattern).

"NZs and Cals don't need contrast between white and dark hairs" (sorry can't get Quote to work).
They don't, but Calis do need dense point colour. I wonder if steel has an effect there too.