[Jacob-list] scurs

[Jacobflock at aol.com]

In a message dated 5/3/01 12:11:53 PM Central Daylight Time, SharHill at aol.com 
writes:

<< There was a discussion a while back about scurs.  I was too busy to jump 
in, 
 but now maybe someone could clarify something for me.  I see the definition 
 of a scur as "a small rudimentary horn that is not firmly attached to the 
 skull."  Does this mean that a true horn never develops?  Last year I had a 
 ram lamb whose side horns fell off when he was a couple of months old, but 
 then grew back firmly.  Why does that happen?  Is it "normal?"  Is it 
 considered a problem?
  >>

I think we use the terms horn and scur based on what we think we see but 
genetically the terms HORNS and SCURS are different and their biological 
structure is different.  HORNS have a core that runs substantially the length 
of the sheath and are firmly attached to the skull, loaded with blood and 
even act as part of the cooling system for the body.

SCURS are genetically and anatomically or physically different.  The scrur 
locus has three alleles (forms) which have the following dominance: ABERRANT 
horn, Long scur and short scur.  

The aberrant horn looks like a "horn" from the outside but is very small, 
flimsy, has virtually no core, diameter like a pencil or flat like thick 
corrugated cardboard, and may be concave in cross-section but again very 
thin.  It is wobbly and if you think it is going to come off when you grab a 
lamb...say at six months or older...it is probably an aberrant horn, a form 
of the SCUR locus.  (The long and short scur alleles look plastic, wax or 
"hard" pudding....don't even really look like horn material...should not be 
an issue).

I think aberrant horns are more oftem seen on ewes than rams.  Wobblely, 
flimsy, and if broken off, the "core" in the sheath is 1/2 inch or less deep, 
there is far less bleeding than breaking a horn core.

The lamb's horns and skull are rather weak stuctures until they are almost a 
year old.  The skull plate sutures are loose the attachment of the horn core 
to the skull plate is growing.  Lambs have a weak skull and a severe mental 
weakness...they think they can get through any opening that is as wide as 
their eyes.  Lamb creeps and holes in fences are a major benign threat to 
horns...especially drop horns.  If the lamb breaks a horn, typically the 
lamb's small horn break includes a break of the core at the skull attachment 
(the lamb's face, neck, torso and leg are a mess), and it takes a while for 
this to heal and rebuild.

If a "horn" drops off...and there is virtually no blood, it is probably an 
aberrant horn.  Look for horn pieces around the door, a creep, etc.,  look at 
the base and see if the core goes into the "horn".  Horns generally grow 
back, aberrant horns generally don't.  

Not all horns are horns.  Why are aberrant horns present in Jacobs?  It is a 
resut of the scur gene.   Fred