[Jacob-list] Re: Horns and scurs

[Linda]

This subject is fascinating and perhaps way beyond me.  In speaking of scurs that look like scabs and are seen in 
polled animals - what would the skull look like?  I have 2 older ewes that do have 2 true top horns, 1 true lateral, 
and a scabby spot where the other lateral would be.  These are obviously not polled as I don't guess you can be 3/4 
polled! Perhaps they carry the hornless gene. If I palpate the head I can feel what I think is a horn core coming from 
the skull. Is this a scur?  Since neither of these ewes grew up here, I never saw them with their baby horns.  We used 
to have meat sheep, but I never did palpate their heads, so I don't have a true polled skull to compare.  One of these 
ewes is going to the butcher and I will get her skull back to examine.  Fred, have you examined skulls on scurred ewes? 
 I keep ram skulls on occasion  and am familiar with ram structure, but haven't thought to keep ewe skulls before now.

Linda

On Fri, 2 Jul 2004 19:41:45 EDT, Jacobflock at aol.com wrote:
>In a message dated 6/8/2004 1:48:06 PM Central Standard Time,
>nlgrose at yadtel.net writes:
>
>My feeling is that we make too much of the difference between "scurs", "weak
>horns" and "true horns". (I am not talking about the true scurs that look
>almost like scabs. These are sometimes seen in polled animals.
>
>I suspect we make too much of it because they are scientifically different and
>have a genetic basis.  Sheep Horn/Poll gene seems to be on chromosome 10
>(Montgomery); on cattle you probably are aware it is on chromosome 1.  The
>Hornless gene which produces scurs and aberrant horns is sex linked, found
>only on females.  The gene in cattle (called the scur gene) is located on
>chromosome 19; a gene creating an effect other than horns.
>
>The Jacob horn core is loaded with veins, arteries and seeming capillary to
>the horn sheath.  The aberrant horn and scur ( a set I sent to Gary Anderson
>at UC-Davis) has no such structure.  The inside of a aberrant horn is a "bump"
>or big "pimple"; the inside of a scur is almost a dense plastic like material.
> I tend to agree with the conclusion that horns and aberrant horns and scurs
>(long and short) are not the same, are structurally different and have
>different genetic causes. The sheep may have homology/synteny with the cattle
>scur.
>
>That there are scurred Jacobs or Jacobs exhibiting the Hornless gene phenotype
>is not entirely unexpected.  These have been "accepted" as "Jacobs" in the
>registries. Registration of lambs (before horn developmemnt), selective
>registration of sheep (not submitting those that might fail), sending "off-
>sheep" to the auction yard (which re-enter the systems) are all sources of the
>hornless gene.  I am not diminishing the good faith judgement of the people
>that review these sheep but offering a set of circumstances that support the
>intermittent appearance of the hornless gene.   Understanding the horn gene in
>sheep is a recent event (1995) but the difference between and inheritance of
>polled/horn/scurred types has been known for a long time.
>
>Fred Horak


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