[Jacob-list] Horns and scurs

[Jacobflock at aol.com]

"Scurred horns" might be an oxymoron.  Scurs are not horns.  Some scurs may 
look something like horns but the "plasticized" appearance and absence of the 
characterisitc fibrous keratin, shape, lack of growth and stubbiness often 
give them away.  Aberrant horns have the fibrous keratin but are thin, lack a 
real horn core, are extremely weak and often "fall" away.  

Horns and scurs are species specific, may even be breed specific within 
species and is only recently being explored.

CATTLE: The horn gene in cattle was only confirmed as located on chromosome 1 
in the early 1990s.  Scurs, which are small "horn-like" growths but not true 
horns, and aberrant horns which might be described as "floppy, weak, 
diminutive" horns, have been described for over 100 years.  Until the 1990s, 
domestic animals with horns were thought to have a "horn" gene/or "poll" gene 
on chromosome 1.  The presence of scurs was also thought to be on chromosome 
1 (related to the horn gene) but there is now evidence it is not always there 
but 'somewhere' else. 

SHEEP: For many years it was assumed anything with horns had a "horn" gene on 
the same chromosome 1.  In 1996, the common theory that the sheep horn locus 
was also on chromosome 1 (like cattle, etc.) was dispelled by G.W. Montomery, 
et al. and placed at chromosome 10.  This reference can be obtained from your 
library: Mapping the horns locus in sheep - a further locus contrrolling horn 
development in domestic animals. Journal of Hered 87, pp 358-363.  Montgomery 
et al is related to 2 horns.  Because there is a difference between two and 
four horn, Alderson proposes that the horn condition might be HO (two horn) 
or HMN (multiple horn).   Two and four horn location and dominance are still 
questions.

Scurs are not horns, the Sc gene is PROBABLY at another locus, and there are 
two situations that must be considered <<or else it would not be confusing>>: 
(1) 2 horn sheep and (2) 4 or multi horn sheep. 

Scurs (Sc) are described as AN AUTOSOMAL LOCUS that includes scurs and 
aberrant horns in both rams and ewes.   Hornless (Hohl) is described as short 
scurs, long scurs and aberrant horns which IS SEX LIMITED and observed only 
in ewes. 

If the Jacob is "horned in both rams and ewes", short scurs, long scurs, and 
aberrant horns should not be present.  Very few breeders have reported 
polled, scurrrred and aberrant horn offspring from two horn parentage.  When 
born, they are culled without questioning the sire or dam and their pedigree. 
 

Four horn sheep are sometimes reported as having weak or scurred lateral 
horns; sometimes it is observed only after being registered.  A few 
Jacob-listers have reported apparent scurs and aberrant horn observations 
related to the lateral or drop horns of apparent four horn offspring.  These 
reports are not unequivocal and sometimes explained by trauma but most scur 
and aberrant horn observations seem to be limited to ewes.  This seems to 
suggest consideration of the Hohl allele which is sex limited  ... the Hohl 
interacting with the HNM (multiple horn) locus affecting four horn ewes.  

I put part of this year's collection of Hohl evidence in the mail before 
taking any pictures but several pictures of Hohl "jacobs" with scurs and 
aberrant horns are available in books (I. Painter), periodicals (JSC Journal) 
and video tapes (TN Public TV).  Pedigree sources for scurs may be found in 
the AMBC Jacob listings and registry flock books.

Fred Horak