STOCKYARD
HORSE  DISCUSSION FORUMS

Em

There is also this horse now in Aus - Home If my little paint mare was younger I would be getting AI for her without a doubt!

nannygoat

TB's arent allowed to use AI and I hope that they test all paints they breed because I believe he is lethal white positive.

But I love his 'eyeliner'!

Em

Damn - just read that, will have to transport the girl to NSW Oneday hopefully a coloured baby of his will make it's way over here! He does cary the overo gene which is lethal in homozygous form but when bred correctly to identified sabino's or tobiano's there will never be an issue with lethal white as of course both parents need a copy of the overo gene. You actually get a double chance at chrome with him as he is a genetic sabino as well as overo - so I guess you could call him sabero! Perfect outcross for the Paint horses - there is an article on him in the latest paint horse mag!

White_Horse

maby coloured t/b started from one mutated/throwback gene,
then people bred the coloured t/b untill there were many of them,
i know thats how they got white t/b's.

i would LOVE a pure white t/b.

simbin

Apparently not colour has come from the many english mares and also through the arab stallions that were originally used when producing the thoroughbred man many moons ago in England. We forget that the thoroughbred is a recently developed breed. So of course you are going to get throwbacks etc. My thoroughbred I have just discovered is actually a sabino and there are many of those around. White flecks and markings through coat, unusual head markings which goes under the lip and chin.

I have found this topic very interesting. Go and have a look on some of the links put on this thread at some of the coloured australian thoroughbred who have been bred.

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Em

There is another article in the lastest Paint Horse Journal on 'The Science of Sabino.' Fascinating read about discovery etc of the sabino gene SB1 and how it works etc and the homozygous form is of course your extreme white horses which are maximally expressed sabino's. According to the article if a horse has two copy's of the SB1 gene homozygous(purebreeding) they will have to have maximally expressed colour. It is caused by a single dominant gene - unlike the tobiano's where it can often be hard to distinguish between homozygous and heterozygous as that gene for colour is polygenic(coming from more than one gene) so you have other modifying factors come into play. The study was actually done on the appearance of all white foals in the Tennesee Walking Horse breed - similar history to the TB with random appearance of white foals from plain ordinary parents.

Taken from the article...

Sabino 1 characteristics

Heterozygous SB1 horses generally exhibit three of the four following characteristics:

- two or more white feet or legs
- a blaze or white patch exending the length of the face
- jagged margins around white areas
- spots or roaning in the midsection

Homozygous SB1 horses are mostly white, at least 90 percent depigmented at birth.

mirawee

Em, there must be something else modifying the sabino gene though as it is possible to get minimally marked horses who through maximal whites So I am very suprised that they are saying it is a single gene.

Well actually I guess it is a single gene for "on/off" then other modifier genes also at work.

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Change is inevitable. Change for the better is a full-time job.

Em

My understanding from what I read is that there are alot of horses out there that may show the sabino phenotype but not necessarilly have the SB1 genotype. Also though a maximally expressed true SB1 homozygous horse will throw 100% sabino foals BUT if the dam is not sabino they may only be expressed as minimal sabino as they only have one copy of the gene. But yes there are always other modifiers at work when it comes to white markings but the way the SB1 gene works is that is twice as stong when two copies of the gene are at work compared to just one copy. Hope this makes some sense!

They were actually talking also about the draught horse type sabino - you don't find any white clydies that I have ever heard of and that might be a different sabino type mutation again - NOT the SB1 mutation that is the cause of white TB, Arabs and Tennesee Walking Horses. But that is definately dominantly inherited also. Fascinating stuff

jmrchook

In the June July issue of Hoofbeats , there was an article on the T/Bred crop-outs.

Did any one read this?

I have a chestnut with baldy face 4large stockings over his knees and belly splashes as well as white under his jaw line.

I have been told he would have been eligable for reg as a paint , but the reg. needs to have a coloured parent and as he is t/bred that is not the case.

Can any one help me with this?

Any info would be great.

Kintara

The SB1 isn't that common (or even known?) in arabs and TB's either. The all white TB's and arabs are another sabino gene, or dominant white (which some people figure is just more sabinos anyway) SB1 seems to be most common in breeds like the walking horses etc.. Sabino as we know it in arabs, clydies etc.. isn't SB1. So although they have found SB1 it hasn't helped a lot as far as testing for most sabinos yet. It's a start though!
Cheers

Danni