Silver Dapple gene in Arabians

Discussion in 'Breeds, Colouring and Genetics' started by ambatt, Jan 3, 2006.

  1. ambatt

    ambatt New Member

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    On another forum I use there is a current debate on the silver dapple gene being expressed in the Arabian breed.

    They are suggesting that the silver dapple gene in Arabians shows as a plum coloured chestnut with lighter mane and tail. As far as I am aware this does not appear to be what I would class as 'true' silver dapple colouration as found in Icelandics, Shetlands, Highlands and Rocky Mountain Ponies.

    Chev, do you have any theories or opinions on this colouration in Arabs? I thought you needed the horse to be genetically black to allow the expression of the silver dapple locus? The true black Arab is of course exceedingly rare.

    But you could write my knowledge of genetics on the back of a postage stamp.
     
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  2. chev

    chev Moderator

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    Silver dapple only dilutes black pigment; it has no effect on red. So yes, it is mainly seen expressed on black horses; but is also visible on bays, where it can be mistaken for flaxen chestnut.

    The actual shade it dilutes to does vary widely though. In some horses it's seen as a dark chocolate body colour with an almost white mane and tail, while others have a paler body. It can also appear different when it's seen in conjunction with other factors (dun, cream and so on).

    Arabs don't carry cream, but it's believed some of the Egyptian lines do carry silver dapple. Arabians also sometimes carry a dilute factor known as lavender; which is also strongly associated with neurological problems and often death early in life. Affected horses sometimes survive to experience symptoms such as seizures.

    Silver dapple won't be expressed on a chestnut base; so if both parents are chestnut, what you see is another chestnut.
     
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  3. chev

    chev Moderator

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  4. ambatt

    ambatt New Member

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    Thanks very much for that Chev - I did not think the genetics were correct to give silver dapple colouration in Arabians? The shade they refer to is this very specific plum shade with lighter mane and tail. I do not have enough genetic background to conduct a strong enough argument to suggest that the colour they are describing is GENETICALLY not silver dapple.

    My Icelandic mare although gentically black, is 'mobrunn' in Icelandic and is the colour of a silver dapple but without the light mane and tail, as such I suspect she is a silver dapple carrier.

    The Lavender gene in Arabians I knew about, as I have had the priviliege of seeing one, but she was PTS at a week old due to the neurological disorders she had. Beautiful truly mauve colour though - I will probably never see one again.
     
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  5. chev

    chev Moderator

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    Have to say what you describe really doesn't sound like silver dapple.

    I've not seen anything myself that looks like silver dapple in Arabians; but equally I've not read anything that states it doesn't exist in the breed. Are there any pics of this colour? It sounds intriguing, whatever it is!
     
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  6. ambatt

    ambatt New Member

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    Typical - my pooter just crashed in mid-reply!

    Interestingly, there do not appear to be many photographs of these 'plum' arabians. My own personal theory is that they are a variation of the liver chestnut colouration, although I have no genetic basis for this argument. Could it be an expression of the 'sooty' gene which does I think, work on a red base coat?

    the original forum debate is here,www.arabianlines.com/forum1/topic_new.asp?TOPIC_ID=9373although the silver dapple question has got mixed up with the sabino and roaning genes.

    I did however, find this site on silver dapple colouration in Morgan Horses and also false silver dapple colours.

    http://www.mindspring.com/~morgans/silvermorgans.htm


    Hope the above have whetted your geneticists appetite!
     
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  7. chev

    chev Moderator

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    Based on the photos I've just seen in those links, I'd be inclined to agree that these 'plum' Arabs are liver chestnut.

    One reason being two of my Welsh mares... who are, according to the descriptions given, typical of the 'plum' colouring.

    Note the 'distinctive' body colour, along with the silver grey mane and tail....

    [​IMG]

    Tia's dam was buckskin, sire was liver chestnut. I'd have put her down as liver chestnut with interesting colouring to be honest. Her mother certainly doesn't carry silver dapple in any way (she has such lovely black points!) and I think it highly unlikely that her sire does.

    This is the other; the pic doesn't show her grey mane and tail very clearly but she has the same plum body colour. No idea what colour her mother is; but her sire is liver chestnut.

    [​IMG]

    I do doubt that a gene that's relatively rare in Welshies should crop up in two of my mares... ;)
     
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  8. ambatt

    ambatt New Member

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    Chev, this lab will genetically test your horses's colour genetics - the other forum thread suggests that they do not test non- US horses - they do. Now, would you not have thought that was the easiest way to prove or disprove the existance of the silver dapple gene in Arabians?

    http://www.vgl.ucdavis.edu/

    Here is genetically black Nott showing the dilution effect of the Z locus.

    [​IMG]
     
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    Last edited: Jan 3, 2006
  9. ambatt

    ambatt New Member

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    Indeed Chev - also your rather beautiful mares look distinctively Araby too! So could it be the sooty gene?
    Perhaps you should join the AL forum just to post the colour of your mares, if not I could alwys post them, if you agree?
     
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  10. chev

    chev Moderator

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    It would seem the sensible way to prove it one way or the other. The cynical part of me wonders if that's why these horses are not tested.

    I thought there was also a lab in Europe who will test for colour genes? Could be wrong though.

    Please feel free to post the pics of my mares! It would be interesting to see what they make of them :D
     
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  11. chev

    chev Moderator

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    Liver chestnut is thought to be a result of sooty on a red base. The gentics of mane and tail colouring really aren't understood; it is something I'd love to know more about though.
     
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  12. ambatt

    ambatt New Member

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    The even more cynical part of me would suggest that *if* you had an alleged silver dapple Arabian you could charge huge amounts of money for it? Surely to breed a silver dapple arabian you would need one black parent?

    OK I will post your photos and not mention the fact they are Welsh Ladies and see what transpires.
     
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  13. chev

    chev Moderator

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    Hmm... in theory you could breed a silver dapple from chestnuts that carry the gene; but to be expressed there would have to be a black base, so you'd have to have one black or bay parent at least for that to happen. A chestnut with silver dapple just looks like a chestnut.
     
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  14. ambatt

    ambatt New Member

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    Your girls are on! Will sit back and see if anything happens.
     
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  15. ambatt

    ambatt New Member

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    and finally:
    [​IMG]
    Copyright Lukka

    This horse is a false silver dapple! He is out of a liver chestnut mare by a sire who gets flaxen haired chestnuts. There are no true silver dapples for a few generations. His colour is registered as liver chestnut with flaxen mane and tail - seems reasonable to me.
     
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  16. chev

    chev Moderator

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    I've seen a few Welshies with interesting takes on liver chestnut.

    Nebo General Pride

    Nebo Daniel

    These are two of them. Nebo Daniel in particular is striking to look at in the flesh.
     
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  17. ambatt

    ambatt New Member

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    Nebo Daniel is stunning and I would certainly class him as liver and I do remember seeing Welsh Cobs with the liver/flaxen colouration. He is a stunning horse to look at - my kind of Welsh Cob! I also note that his sire is a roan!

    The other one is interesting for the metallic sheen on his coat, also I think he is nearest to the plum colouring the Arabian lot are referring to.

    I think it is very subjective of them to try and gauge the colour of a horse by mere appearance alone. We all know how the eye can deceive, so I guess the only answer is to actually have the genetics done and take it from there. Given the amount of false silver dapple colours there are, you cannot base a hypothesis on something so unscientific as the beholder's eye!
     
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    Last edited: Jan 3, 2006
  18. ambatt

    ambatt New Member

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    For future reference there is somewhere in the UK that will colour test DNA to ascertain colour genetics:

    http://www.animalgenetics.us/Equine.htm

    Thanks for a really interesting discussion Chev, it has really exercised my grey matter!
     
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  19. GOBBY

    GOBBY New Member

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    Im one of them arabian lot,!!!! Great website and a lot of great friends, and neighbours on there,
    can see what your getting at, but going by what your job is, your obvously far from stupid,and proberly do know more than could possibly be on back of postage stamp.
    whilst you were, are, waiting for replys back from AL, following both threads here and there whilst being a member of both websites!!!!! feel it is a little naughty.
     
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    Last edited: Jan 4, 2006
  20. chev

    chev Moderator

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    Sorry you feel that way; but I am actually really interested in the replies on AL. I have tried joining there in order to join in the discussion but something goes awry; I can fill in the members' details page but when I accept the terms and conditions instead of sending me to the 'fill in your user name' page it just directs me to the main forum, and I can't get any further :( . So this is the only way I get to follow it.

    The Arab influence in Welsh ponies is undeniable; sabino in Welsh ponies almost certainly came from the Arab blood so if silver dapple exists in Arabian lines it's also possible that the silver dapple in Welsh ponies came from there.

    I am genuinely interested in the discussion on both forums; please don't think I'm not.
     
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