[Jacob-list] Question about horn genetics, scurs and breeding

[Jacobflock at aol.com]

In a message dated 5/19/2006 2:04:23 PM Central Standard Time, 
sharonehill at yahoo.com writes:

> Several years ago I bred a 4-horned ram with a nice
> solid set of horns to a 2-horned ewe who also had very
> strong wideswept horns.  They produced a pretty  4
> horned ewe lamb.  But the lateral horns never really
> developed and just fell off.  


It is one case to say "fell off" which suggests aberrant horns, it is another 
case if they "broke off" as the result of trauma which produced hemmorage and 
evidence of horn core.


She has nubs where they 
> used to be.  


This suggests aberrant horns.


I guess these are scurs?  Her top horns
> 
> are tilted forward and she had broken one of these in
> half. To put it bluntly, her horns are ugly. Her
> fleece is pretty good and I kept her for that.
> 
> I never bred her til now, when the ram squeezed into
> the barnyard and had his way with her.  He is a 2
> horned ram who is exceptionally pretty, with spots in
> all the right places and very strong wideswept gently
> curving horns.  His fleece is excellent.  
> 
> This breeding produced a healthy and very nicely
> marked 4 horned ram lamb.  
> 
> I am questioning whether to keep this lamb as an
> intact ram or not.  Please forgive my ignorance of
> genetics that I am sure I will exhibit in the
> following questions.  My teachers always told me there
> is no such thing as a dumb question, so I will put
> that to the test.  I hope for some interesting
> replies.
> 
> 1.  I am wondering why the ewe with the scurred
> laterals had them in the first place.  As I said, both
> parents had nice horns.  I never saw the grandparents,
> but they were from registered stock. 
> I am assuming there a gene for scurs, am I right? I
> hope so as the rest of the questions are based on that
> assumption. 



The ewe, not the ram, exhibits the hornless gene (Hohl) and is apparently 
carried as a recessive.  There is a gene for scurs that produces short scrus, 
long scurs and aberrant horns.  One must be careful in equating registered stock 
of any species or breed with pure-bred.  

> 
> 2.  Are Jacobs registerable if they have scurs?
> 


Sheep carrying the Hohl gene have been registered.  The distribution of the 
Hohl gene becomes accelerated through the purchase of lambs, recalling a case 
of a breeder's offering of about ten lambs at a sheep show, each of the six ewe 
lambs with very questionable "horns".  They were sold as registered or about 
to be registered.

It is poosible for two horn sheep to carry the Hohl gene; the nice thing 
about the two horn is that they will not exhibit the gene.

> 3.  If this lamb develops well, and has nice strong
> horns, will he necessarily carry the gene for scurs?
> 

After eight or nine seperate breedings you will have a 95% probability as to 
his type.  One parental boo-boo is a boo-boo.

> 4.  Do other breeders use rams with a background like
> this for breeding?  Are people trying breed this trait
> out?  Is it possible to breed it out?  I assume there
> are carriers of the gene who don't exhibit it who are
> unknowingly passing it on to their offspring, as has
> happened with my ewe.  
> 


I suspect some breeders use Hohl carriers but the reason can be as far 
ranging as ignorance, having only ram available, and "who cares".  On the other end 
of the spectrum is a mid-west zoo that offers a "Jacob" exhibit with polled 
Jacobs ... and the lambs are born polled ...  and a four-horn ram. 

I hope that breeders are trying to get rid of the trait whenver found.  If 
too many are found and some breeders have problems selling their sheep, there 
may be an effort to change the Jacob to polycerate rams and polycerate or 
hornless ewes.

> 5.  In other words, if others aren't culling for the
> trait, will it make any difference if I do?
> 


The purpose of my flock is ______________________ .

> 6.  Is the gene always passed on?
> 
> 


Hohl is apparently a recessive.  About five years ago we brought in a 4H ram, 
bred him to three ewes and he produced, three 4H rams and a 4H ewe.  The 
following year he produced a couple of 4H rams and 4 Hohl ewes.  I think I sent 
the findings and horns to Gary Anderson.  We butchered.

 
> 
> 7.  Are forward pointing horns a genetic trait?


It is our experience (about a half dozen cases) that horn direction is mildly 
influenced by the opposite parent.  Hardly conclusive.

> 
> 8.  Have I asked enough questions?  I am sure there
> are more I should be asking.  But that is all for now.
> 


Good questions, all.  I have sent an attachment ot this file to you which may 
help explain the horn and hornless traits in greater detail.

Fred Horak
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