[Jacob-list] fading

[Kelly Foster]

Hi,
I have two ewes here that are showing early signs of greying. Both are lilac
carriers but neither are lilac. Anyone else noticed this trait ?
Also, should we cull these girls because of this early greying gene? I know
some that have. Just wondering what others have done.
Kelly
 ----Original Message-----
From: Jacobflock at aol.com <Jacobflock at aol.com>
To: blotham at yahoo.com <blotham at yahoo.com>; Jacob-list at jacobsheep.com
<Jacob-list at jacobsheep.com>
Date: Tuesday, October 17, 2000 10:01 PM
Subject: Re: [Jacob-list] fading


>Fred Horak here.
>
>The fading (black fading to dark brown or brown) of the Jacob black was
>described in 1926 by Dr. Fraser Roberts but its cause was not entirely
>understood.  The fading of black to dark brown or brown) is probably a
>complex issue for biochemistry: the amount of eumelanin (a tyrosine polymer
>that makes black) in the fiber, ultra violet sun damage, diet and the
amount
>of copper (a metal that builds eumelanin), dust in the fiber scales.
>
>If the fading is to grey (not to be confused with lilac), there is another
>issue to address; a graying gene which promotes "premature" gray and seems
to
>be dominant.  Lambs are born black/white but by age two or three are greyed
>(fleece is grey and the root black has significantly diminished in
intensity.
> By way of "simple" explanantion (nothing is really simple), it seems as if
>the follicle from which the fiber grows (melanocyte) has stopped producing
>eumelanin.  Under the microscope, the gray fiber does not seem to have as
>compact and dense chains of black: black fiber looks like this ooooooo;
grey
>fiber looks like this o o o o o o (fill in the o's with a black pencil for
>Jacobs, use a red pencil for barbados).
>
>Complex problem but a good observation on fading.  We see a lot of fading
>here in TX.   Fred Horak.
>
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