Behavior of the Silvering Gene

[PulpFaction]

Hi all. I am trying to better understand the behavior of the si gene and whether or not it is the same gene responsible for some appearances of white hairs in other breeds.

I have a Thrianta doe that is exhibiting pretty classic silvering, including the silvering becoming more apparent with every molt.

On the other side of things, I have an unpedigreed, possibly cross bred "Silver Fox" doe with very light silvering. When compared side to side, it's nearly identical but obviously, one is more silvering than desired and one is less than desired.

I guess my question would be, how do I best adjust this in future generations? Is this the kind of gene that, when these does are bred back to the ideal for their breed, the offspring would come out with the desired less and more silvering, respectively?

Should I completely eliminate the Thrianta doe from my breeding program, despite the fact that she has many very desirable traits that I would like to include in my line? She is from a different bloodline from my others and none of the others show any sign of silvering, so I was hoping this is a trait I could basically eliminate in a generation or two as long as it is just the single outcross to the offending line.

On the other hand, how long a road is it back to achieving a desirable level of silver in the SF from this apparent crossbred. (She also has good traits, including a very nice head and ear and shoulders to die for.)

I'd love input from anyone familiar with the si gene in rabbits.

 

[ShadedNightRabbitry]

I don't believe the silvering gene is *specifically* what causes most white hairs in rabbits...
Although, I do know that it can be mistaken for just plain old white hairs, which ends up getting the rabbit culled... Which is why a lot of breeds that can be silvered (not sure if that's the correct term), don't have many around.

For the rest of the question, I don't know.

 

[Devon's Mom Lauren]

The silvering gene is pretty dominant, you only need one copy for it to show up.. However the amount of silvering is also controlled by modifiers. So yes a rabbit that has a lot of scattered whites may have that gene. If the thriantra has a lot of traits that you otherwise want you may want to keep her anyways and just keep the kits that don't seem to have the white hairs..It is hard to get rid of yes, it may take a while yes, but if you breed to a correct for colour Thriantra you should get some that are also correct for colour. Our second generation crosses showed very little silvering and some none,(their grandfather is an Argente with heavy heavy silver, mom actually looks like a silver fox way less than dad!) so not impossible to get rid of or get back! Just the fact that the Thriantras are hard to come by I would keep her, if she was a very common breed then I might not bother. But in this case with both silver Fox and Thriantras quite rare I would defiantly go on from them and try to breed for the correct sop of each breed!

 

[akane]

Silvering is recessive. It takes 2 of the gene to produce silver so you can hide it pretty easily but if you have a small population of rabbits it will be hard to eliminate completely. Breed to a rabbit without silver and that entire generation won't show it but will carry it. Until you breed the line back on itself or to another line carrying silver you will not see silver and if you wait enough generations you may never see it again. It's hard to be certain it's completely gone though since they can carry it without showing any white hairs.

The more and less white hairs is probably a modifier gene(s) and breeding to a rabbit that is ideal or the opposite extreme may give you what you are looking for. It would be more predictable to breed to an ideal rabbit but may take longer since there may be less modifiers in the direction you want to go. This does not apply to getting rid of all the silvering. It doesn't matter how little silvering a rabbit has. If you breed 2 rabbits that have the gene you will continue to get silver offspring.

 

[Devon's Mom Lauren]

You only need one si gene for it to "show" We bred an Argente to a non silver and all 8 were sivered even though there was only one copy of the gene passed to them from the father. Modifiers play a big deal here. If you are only playing with a single gene out of a pair then the odds are 50% that you won't get it, and 50% that you will.In other words if its there it shows in whatever amount, which is why most stay away from it, unless, thats what they want!<br /><br />__________ Mon Nov 29, 2010 9:23 am __________<br /><br />http://omegascachetdwarfs.yolasite.com/champagne-project.php
Sorry forgot to include a link to a ND project for silvering.. The first picture is a F1 cross between a self black (non silver) and a Champagne (Homozygous silver) The cross shows a goodly amount of silvering but much less then the original parent.This example has one copy of the gene and looks pretty much like our meat crosses did.

 

[DevonW]

This is a cross between an Argente Brun and Harlequin :

Not as much silvering as the father did but for a Jr coat it has a fair amount.

This is the father:

The cross doe was bred to a Satin (1 quarter Argente litter) and ever single one of the kits had started to silver before they left.

So the gene is definitely not recessive.

 

[akane]

Every source I look at says it is recessive. Not just some but every single one lists it as sisi=silver and SI_ = normal. http://www.debmark.com/rabbits/genetics.htm , http://www.nockrabbits.com/ticked.html , http://www.tomatinstud.com/4793.html?*s ... on*id*val* ... So they are either all wrong, there are 2 possible genes causing silver, or the breeds they've been crossed out to actually carried silver.

 

[DevonW]

The only link that has silvering written down as sisi is the Nock Rabbits one. The other two just list it as si, which the Evans Genetics program does as well.

This is what the Brun Genetics looks like : aabbC-D-E- si and the amount of modifiers present in the si gene will effect just how much silvering they get

 

[akane]

Recessives are always marked with lowercase and dominant with the same capital letters. Only sort of exception is when there are more than 2 genes on a locus and then they frequently use superscript such as with the C genes. If you look at the rest of the genetics listed on those sites they all follow that pattern so they aren't just writing them wrong. Also on the Tomatin site it says

Si – Silvering gene as seen in the Silver rabbits. Si produces normal coloured rabbits. si present in its homozygous pairing produces white tipped hairs throughout the coat giving a ‘silvering’ effect.

Homozygous means having 2 genes of the same thing. Heterozygous is when you have 1 dominant and 1 recessive with the dominant being displayed. So the only one I posted not specifying in detail that 2 genes are needed for silver is debmark.com which lists non silvered as being the capital and therefore dominant version.

I have more genetics links but my favorites folder is a mess right now.

 

[Devon's Mom Lauren]

In this case yes the gene for silver is written wrong. SISI is not written down to designate a non silver rabbit. Written genetics is not necessarily "correct" . Also Pam has the silver gene mixed in with the Steel gene and some sort of ticking gene which are all different things. Please realize that these links are to other rabbit breeders who may or may not know everything. The pictures are there to see and there were 8 of the same. I also provided another link of this happening with a ND dwarf champagne project. It is not as simple as dominant /recessive, there are many incompletely dominant/recessives as well.

 

[Honorine]

I breed Silvers, and I've also had Creme d Argents. I've bred them to a number of different breeds all with the same results, all of the kits were silvered in varying degrees. Silvering is dominant, and there are modifiers that control the amount of silvering. It is possible to breed away or towards more silvering, I do it all the time by crossing heavily silvered rabbits with less silvered ones. In the litter you get a range of silvering types. Even breeding heavily silvered to heavily silvered can still produce some rabbits not as silvered, but its still there.

Back to the OP's question about silvered Thrianta's, Silvers were used way back in developing the breed. I have Thrianta's also, I've never seen a silvered one. That said you may be seeing the silvering gene, or possibly the steele gene, as steele is a recessive that can hide for many generations. Its hard to know for sure what could be behind that rabbit, because as you know another breed could have been crossed into those lines to improve something, happens a lot. If its silvering do I think you can breed away from it? Yes. Could it be caused by carrying the REW gene? Maybe, and if thats a possible then a test breeding to a REW is in order. Quite frankly if I wanted to improve type on my Thriantas fast I would cross in a Florida White. Same size, smaller bone, awesome bodies, and most FW's are genetic reds, steeles or blacks. I myself wouldn't do it because I hate the REW gene in breeds where it doesn't belong. I do happen to have some Thrianta Silver crosses right now, their red, and silvered of course, with much heavier bone. Silvering varies, but its there. Because silvering is dominant I 'm not sure it can be carried as a recessive and not expressed like steele can be. Other genes that can cause silvering? Blue eyed white, I have a lovely black otter MR doe with perfect silvering, she's a vienna carrier, and the only expression of it is her silvering. She's silvered evenly and fairly well, I've had brown Silvers with less silvering. Hope this helped.<br /><br />__________ Fri Dec 03, 2010 10:18 am __________<br /><br />Oh, I forgot to address the Silver Fox. I had a very nice brown Silver that had a great body and excellant size. I bought him to improve my fawns, as fawns are so scarce. His silvering was nearly non-existant, had a judge dq him at the county fair because he couldn't find hardly any silvering. Bred him to a heavily silvered doe, first gen I got kits all across the board, some heavily silvered others not, second gen the same with the amount of silvering getting higher. So the answer is if you breed her to a well silvered buck in one gen you can improve the silvering, keep the better ones and cross back and improve it more. Not such a long road.

 

[Devon's Mom Lauren]

Honorine I would love to see a picture of your otter MR with the vienna gene! That sounds amazing, i didn't know that the vienna gene would do that.

 

[Honorine]

I could try to get a picture of her, but I don't know how to post pictures on this forum, or if you need an outside host. Its strange, I really haven't gotten many of the classic dutch vienna marked rabbits in my BEW breeding program, most were just silvered, or had blue eyes, or white toes. Have had a few that were very heavily silvered, even more than this doe is. Had a neat little blue tort blue with two blue eyes, he was cute. Will see about how to post a pic. Love them Argent Bruns, a few chocolate Silver Foxes have been showing up at shows around here, not as neat as the Bruns though.

 

[MaggieJ]

Posting pictures here is pretty simple, Honorine. Use the full editor mode. Below where you type in your message is a place for attachments. Put in the photo as an attachment and add. I THINK that's all you have to do. Maybe I should test that...

 

[PulpFaction]

Here's a photo of the offending Thrianta doe. She was getting ready to go into a molt, so her coat was super dead and standing straight up like a Silver Fox, so this is her doing a Red Fox impression.

I think I'm going to save her for the Red Fox project. I don't have SF buck right now, so Frankie the Thrianta will be going in with the SF does whenever I start breeding again, and a buck from those litters will be bred back to this girl. Hopefully her kits will be red silvered, right?

Honorine, I would love to see your red silvered rabbits. Also, you note that the cross with the Florida White SOUNDS like a good idea, in part because of the finer bone. I was under the impression that you wanted heavier bone of a Thrianta, so wouldn't the fine bones be a bad thing?<br /><br />__________ Mon Dec 20, 2010 9:17 pm __________<br /><br />A couple more pictures. This little doe was in rough condition, she had just weaned a litter of 8 and was on the verge of a molt, to top it all off. That was why her hair was sticking out so nicely!

I have been really impressed with how well she bounced back from that condition. If she didn't have white hairs all over her, she would have been in top show condition about a month after that photo was taken. Even her matronly body seemed to shrink back down and get short and cobby again! Definitely a good trait in a doe!

 

[Jack]

Yeah, and you end up with not great
I was reading an article today about crosses of Thrianta and Florida whites, gist was you get a poor example of either, esp. with the albino gene masking the color carried by the white.

But on the other hand, a heavy boned black tan was suggest to help get tan pattern to complete the belly wrap.

 

[avdpas77]

While I know very little about rabbit genetics, I am familiar with genetics as a whole. There seems to be some disagreement here about whether the "silvering gene" is dominant or recessive. I don't know specifically about this gene, but in most(if not all) animals there are genes that are "incomplete dominants" These genes will not give the "full" effect with only one gene like a true dominant will, but will give a "partial" effect unlike a true recessive gene.

 

[Devon's Mom Lauren]

Yep defiantly a candidate for the silver fox project.. though its hard to say if that's an actual silvering gene or not.. did you say she passed this to her offspring when bred to a normal Thrianta?

 

[akane]

Dragging this up because I have a dozen half Argente half mini rex offspring and not a silver hair on a one of them. I'm told they normally start silvering at 8 weeks and when I bought my champagne does at 8weeks they were nearly white already. At 2-3 months my half champagne and cremes are not silvering at all. If it were dominant I'd have at least half of them with silvering and it should be all of them. They are all solid black or a tanner version of chestnut agouti.

 

[PulpFaction]

You will probably see some white after they molt out their baby coats. There are definitely some serious modifiers at play with the si gene. I can practically guarantee you they will have SOME white after they get their adult coat though! And, most likely, more with each successive molt.