[Jacob-list] Gender Linked Horns, Scurs, & Genetic Letter for Lilac

[ranchrat]

Heel low:
 
Linda:  Go to my website, Tales from Rat World Page, my article (edited
by Liisa Sarakontu, Dec 31, 2007), article 19 on canine colour genetics.
 
http://www.wolven.ca/higgins/ratranch
 
~~~~~~~~~~~~~~~~~~~~~~~~~~
D - Blue Dilution
D is dominant, single or double dose, and allows for full pigmentation.
Recessive d in a homozygous state produces dilute pigment.
D affects both eumelanin and phaeomelanin.
~~~~~~~~~~~~~~~~~~~~~~~~~~
 
Looking at Roy Robinson NDR F I Biol 1978's publication "Colour
Inheritance in Small Livestock," his primary coat type and colour chart;
both dense pigment and dilution are found in the Cat, Cavy, Chinchilla,
Mouse, Rabbit and Rat but only dense pigment is found in the Gerbil and
Hamster.  Things may have changed since 1978, in fact I know there are
developments in new mutations and such; white spotting, roan, dalmatian,
dom silver.
 
I posted this here back in 2003:
 
http://www.shaltzfarm.com/shcolterms.html
~~~~~~~~~~~~~~~~~~~~~
Dilution: 
This gene may not exist in sheep, though it is common in some other
animals. It acts to clump pigment so that some of the clear keratin of
the fiber, reflecting white, shows in the spaces between the clumps.
This makes the color appear 'dilute', or lighter than normal. Some
people consider this gene to be called 'distribution' because of the
clumping. Either way, a black sheep will appear 'blue' gray (not black
and white mixed, but solid plain gray), while a brown sheep would appear
a solid light brown (not brown and white mixed). The key to determining
whether a particular sheep is expressing dilution is to check its
'points'. The fiber on its hair and legs should also be the 'dilute'
color. If not, then dilution is not what is making a blue gray or light
brown color.
~~~~~~~~~~~~~~~~~~~~~
 
I see nothing as of yet to alter the consensus of the outside world
feeling that there is no BLUE in sheep.  
 
Jacobs being dominant black, dilute or the simple word "blue" is
interchangeable.  The addition of "b/b" for chocolate (b is for brown)
would alter the phenotypical expression of the diluted eumelanin to
diluted phaeomelanin thereby explaining the lilac greys and lilac browns
we see.  I don't have real issues over defining how dominant black is
diluted to browns or greys; coloured spots other than black is my focus
for now.  Like breeding for a trait, I do not want to muddy the waters
with too many variables!  VBG  Lilac for simplicity is any colour but
black. 
 
We keep seeing sources that say that "d" (recessive blue) is not found
in sheep so until I read a copy of The Genetics of Coat Color in Jacob
Sheep by Dan Carpenter, I have no comment to uphold that blue does exist
in sheep.  Dan, why "coat" colour?  Coat is most often defined for hair
and Jacob wool is a completely different structure (like coffee cups
stacked on each other).  Hair takes red pigment well, wool does not and
one of the reasons we rarely see great red pigment expression in sheep. 
 
http://www.kolumbus.fi/sarakontu/link/farlinks.html
 
Liisa lists Dan's work, described as "a short text about black and
"lilac"" with the following link that does not work.
 
http://members.aol.com/hobsickle/JacobSheepColorGenetics.html
 
Liisa states there is no blue in sheep so is Dan's article not
convincing enough even tho Liisa lists it on her site?  It was her
comments to me that incited me to ask here on Jacob-L for a genetic
letter for lilac.
 
 
-----Original Message-----
From: Jacobflock at aol.com [mailto:Jacobflock at aol.com] 
Sent: Thursday, August 05, 2010 10:38 PM
To: ranchrat at telusplanet.net; jacob-list at jacobsheep.com
Subject: Re: [Jacob-list] Gender Linked Horns, Scurs, & Genetic Letter
for Lilac
 

> The Jacob breeders in North America may have to propose and prove to

COGNOSAG or other body that a definition is warranted inasmuch as the
"lilac" Jacob is an apparent variety? of the 'true' Jacob, > globally
defined as a dominant black, recessive piebald, polycerate.  Absent
reliable pedigree data (source stock) and genetic testing and some 3rd
party review, a definitive answer for "lilac" will remain 

> hostage to speculation.  

 
As I am sure you are aware, back on June 10th , 2003, over seven years
ago now, I had the ear of HealthGene in regards to drumming up enough
interest in procuring genetic colour test in sheep.  I posted my request
for interest all over the world, even to the sheep colour genetic list
owned by Dr. D. Phillip Sponenberg (I believe his sheep colour genetics
list is no longer.sigh!).  Not enough interest was procured to incite
HealthGene to warrant research to offer us a DNA ovine colour test.  My
discussions prior with VetGen also instilled how very expensive R&D is
in DNA colour testing.  Dr.John Duffendack advised me it would cost
millions alone to get an agouti test for canines and maybe forty or so
years.that was back in 2001 and I heard later there was an agouti test
for ovines in Australia, developed to detect the recessive black in
sheep which can contaminate entire white fleeced flocks (the "white
clip" as Sponenberg so adeptly describes it! Link to his article
below).economics of wool production probably incited a quicker time line
for that particular test.
 
http://www.deerrunsheepfarm.com/genetics.html
 
 

> There are many sex-linked "horn" breeds and, although the Jacob is not

supposed to have the sex-linked "hornless" allele, the evidence
supporting incidents of Ho(hl) in Jacob ewes has been around for at >
least fifteen years and was a consideration in setting up the breed
standard.  In fact, I recall cases of Ho(hl) were shown at the JSBA
meeting in CA.  
 
Do you feel as some do that Jacobs that possess the "hornless" allele
are impure Jacobs (potential recent crossbreeding ancestry?).  I suppose
it poses the question, how important are "horns" to defining the Jacob
as a pure breed.do horns make the Jacob, a Jacob (oh to think it is that
simple grasshopper!).  I recall something about fleece evaluations.but
we do not have those livestock registry hoops here to leap thru (feeling
sleepy.leaping sheepies.). 
 

> Think of the Horn gene as having four alleles: polled, horns, multiple

horns 
 
OK, multi horns.I was told we are to think of the Jacob as a horned
beast (like the cow) BUT (big butt) as cattle with a gene that split the
actual horn core making it multi-horned (polycerate); is this
explanation now incorrect or does it need modification, an explanation
to further tweak some new discovery made recently?
 

> and hornless.  Horns, inside the outer black sheath, have a unique

structure that seends blood in and out to a nasal area (a radiator
system) to the cavae mirabilis.  

> 

>The hornless allele in Jacob ewes expresses three phenotypes at the

lateral: the aberrant horn, short scur and long scur.
 
Perfect!  Hornless versus polled; polled is absence of any horn
whatsoever but hornless (deceiving word!) is the so called "scurs" (plus
or minus regarding size) I was looking for AND the aberrant horn (fake
horn lacking a blood core to feed, therefore keep the horn alive!).
Linda, as a kid I viewed some Suffolk rams with scurs and always
wondered.did that mean they coulda, shoulda had horns or?? 
 

>  First, as some of you know, the true horn is integral to the horn

structure; the expression of the hornless allele "sits on the skull"
structure, the material anchoring the aberrant horn and short/long scur
are >obviously not horn but a plasticized keratinous material.  Whereas
the true lateral horn is part of the skull structure (frontal and
parietal), the hornless allele does not produce a pourous "boney"
structure.  A >"test" for an aberrant horn can be  done on the ewe
between three and six months (CDT time?) ... if the apparent lateral
horn breaks off easily, reveals little more than a trickle of blood and
reveals a >"plasticized" inverted V ... it is an aberrnt horn. Sometimes
one may find a broken horn in the loafing shed; pick it up and look
inside ... if you see a little inverted V it's probably aberrant ...
find the ewe with >the missing lateral and look at the side of its head
... there probably will be a little plasticized bump with little
evidence of blood.   HORNS have  a pourous blood rich core ... scurs are
primarily dense >plasticized keratin material.  Just because one sees a
"black sheath" does not mean it is a "horn".  Scurs generally appear
like a yellow/brown/grey  polished plastic stub.

> 

> If you look up more information on horns, look for info that includes

Montgmery's work (c. 1996) which places the sheep gene on ch10 rather
than using the older bovine synteny analysis on ch1 or an old > high
school biology book. 
 
Excellent tips and pointers.I have my homework laid out for a time now.
Thank you as always Fred.your posts are eternally cherished keepers.
 

>Fred Horak

 
I would like to hear your take on this article Fred.
 
http://www.icelandicsheep.com/mouflon_lambs.htm
 
Is there anything new to you posted here.Mouflon related and therefore
relevant to the Jacob? 
 
Doggone & Chicken UP!
 
Tara Lee Higgins
Higgins Rat Ranch Conservation Farm, Alberta
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    ____(\                Tara Lee Higgins                 /)____
   (_____~>    Higgins Rat Ranch - An ACD is for LIFE     <~_____)
  ( ``  ``                Alberta, Canada                  ``  `` )
   \                  ranchrat at telusplanet.net                   /
    )          http://www.wolven.ca/higgins/ratranch            (
 
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