[Jacob-list] Horns-number, weepy, weak, dystocia, Hebridean

[Jacobflock at aol.com]

Fred Horak here.
  
Two vs. Four horns?  There are no four horn "wild" sheep.  There are four 
horn 'feral',  'landrace' and 'domestic' sheep.  Four horns is a 
disadvantaged condition and that is why two and four horned are often kept 
separate.

Dystocia is more directly related to ewe weight (fat) than lamb size (nds1 
data base).  In our experience recording pelvic size for 36 births (in 
particular the distance between the tuber ischii that are pronounced) the 
pre-lambing tuber ischii distance was .5 to ,875 smaller than the skull plus 
horn diameter.  This suggests that the pelvis enlarged .5 to .875 at birth to 
accomodate the skull and horns but what is not known is how much the 'skull' 
plates moved during birth.  Has anyone had dystocia that can be directly 
related to skull and horn size?  This might be indicated by assisted lambing 
where the ewe cannot move the feet and head out even when the lamb is in a 
normal position.  After presentation of the feet and head, the shoulder/chest 
is the next larger element which can present a problem. 

The "weepy"(?) (a fleshy separation between the base of the horn and the skin 
of the skull) horn problem is not new but has never been specifically 
identified. We sent samples to TX A&M for identification but nothing was 
identified.  Two older references:

The following from Arlington Court's  Parkland Jacob Flock owned by the 
National Trust (England): "On the death of Miss Chischester in 1949 the 
estate and its contents were gifted to the National Trust with the proviso ' 
I should like the NAtional Trust to take care of my Shetland Ponies, Donkeys 
and Spanish Sheep...it being my desire that such animals...should remain at 
Arlington as they have given so much pleasure...'

When George Metcalfe took the position of Head Woodsman of the 60 acre estate 
in 1973 there were 40 ewes and 2 rams with a mixture of 2 and 4 horn sheep 
"with many of the ewes and the rams having forward pointing horns with all 
their associated problems - split eyelid, trouble with horns etc.  Lambing 
took place in the open parkland...shelter and feeding of concentrates was 
unheard of so it was 'survival of the fittest'.

"During the mid 80s we were moving toward a predominantly 2 horn flock 
because the 4 horn lambs seemed particularly susceptible to sores around 
their heads caused by the vast number of flies that we get in the summer 
months. ...."Spot on" has proved to be a valuable aid in head fly problems." 
.... " ' Heptavac P' is used as a simple vacine...although 'Ivomectin' cannot 
be used here because of its toxicity to dung-bettles...there are a number of 
bat colonies here... and dung bettles are an important part of a bat's diet."

Also a note in the 1977, ARK (Fenwick)... "I have been breeding Jacobs (no 
longer rare of course) and most of them have been tormented by head flies 
during warm weather for the whole of the summer."..."We keep a flock of Welsh 
Mountain sheep and have never had any experience with head flies... has 
someone else mastered this problem?"

The problem of 'weepiness' between what we see as horn and skin might be 
associated with the meeting of three 'tissue' materials which in 'plain 
speak' might include: the outer horn material, the special epidermis on the 
skull where it meets the horn and the 'binder' between the outer horn and the 
sheath.   It is our experience that there seems to be a mild heretibility 
associated with this and that the condition is initiated with rain and heat.  
We have had 'some' success with iodine.

On the SUED problem I have found an interesting reference to a split orbital 
bone occuring in toy dog breeds reported out of Cornell ("Dorsal notch of the 
foramen magnum due to incomplete ossification of the supraoccipital bone in 
dogs"; Journal of Small Animal Practice, Vol 30 1989.  SUED is not unique to 
Jacobs but several 4 horn breeds.  The SUED condition was observed and really 
began to be examined as a possible genetic link between Jacobs and Karakuls 
and explaining the "origins" of the Jacob (Littlejohn, 1969, Veterinary 
Record). 

On the weak side horn observation (and scur condition) which includes 
aberrant horns in ewes you may get your hands on "Mapping the horn locus in 
sheep" by Montgomery; Heredity 1996 which includes a genotype segregation of 
horn type.  I think this was on the list before as the hornless gene and the 
hornless gene seems to be recessive.  We have produced aberrant horns/scurs 
(hornless gene) after four generations (without aberrant horns and scurs in 
between generations).  Some insight into its possible occurance may be gained 
from the original ALBC listings describing some of the "early Jacobs".

Some of George Benedict's references from Kinsman are also found in the 
"Enquiry into the origin of the of piebald or "Jacob" sheep by Werner and 
Lady Aldington's book "History of the Jacob Sheep" which many of you may 
have.  It is worth remembering that the early Park Sheep flocks (1910-15) 
belonged to the landed people.  

Further, when looking for ancestors of the Jacob there are at least a half 
dozen breeds that are now extinct (White-faced Horned Mountain (dish face) 
sheep or the original Hebridean which is now extinct c. 1900) that might have 
been the Jacob's predecessor type(s).  There is an interesting reference 
(Walker, 1812) on Hebrideans as "small, thin, lank, with small straight horns 
(?) ... wool of various colours-besides black and white, it was sometimes 
blueish grey, at other times brown and sometimes russet" .  The now extinct 
original Hebridean (similar to the Orkney and Shetland) probably is the 
source for the St. Kilda/Hebridean (black) and the Spanish/Jacob 
(piebald).four horn breeds. (Ryder, 512)  But the connection has a rub:  "It 
is interesting to note that when today's Hebridean is crossed with other 
breeds, the lambs are usually white."  (Alderson, ARK, 1978, Rare breeds in 
British Sheep Industry")  and the Black Welsh Mountain is a dominant black.

The Jacob Sheep Society started in 1969 for the pupose of setting a breed 
std. (e.g., no evidence of SUED), improving the Jacob conformation and making 
it commercially viable (Aldington).  See also the plea by Oryx magazine to 
keep a group as unimproved.  The JSS beed standard and SUED eradication 
effort began five years before the RBST began to catalog congenital defects 
among all rare breeds;   The chronology presented by Kinsman may be slanted.  
The Jacob was removed from the RBST aegis as a "non-rare" breed about 1975 
and the defect continued to be reported.   The RBST has been involved in some 
recent controversy for its conservation of the 'modern' St. Kilda/Hebridean 
and Soay because of the practices of 'flock' segregation and selective 
breeding. 
   
Fred Horak