[Jacob-list] Stress, Mineral Deficiency, or DEPIGMENTATION?

[Jacobflock at aol.com]

What is the black fiber?  The black pigment you see are eumelanin granules. 
Eumelanin is produced by oxidation of tyrosine, an amino acid, that interacts 
with copper.  The melanin is formed in the fiber follicle called a melanocyte 
which is produced a few days after conception.  Eumelanin has rich anti 
oxidant qualities.  The eumelanin producing melanocytes which produce the 
fiber ... and hooves,  and horns, all require copper.  (A copper, anti 
oxidant, roof, for analogy, resists rust ... rust is an oxidation of iron).  
The presence of iron reduces anti oxidation (leads to fading), copper 
increase anti oxidation and tends to reduce fading.  Copper in sheep should 
be above deficiency and below toxicity.  Many locations can be copper 
deficient or high in molybdenum as Gary pointed out; others may be rich in 
iron.  But why a sudden change as I understood was described in the post?  
Was an iron diet involved?  Did they go off pasture onto iron, or was a 
change made in pasture or feed? etc.?

Which leads to the larger question that often appears on the List: What 
factor(s) cause 'depigmentation' in Jacobs?  What factor(s) cause an 
overactive piebald gene? white hooves?  What are indicators of 
depigmentation? "blue eyes"?  lilac color?  Is piebaldism in Jacobs linked to 
"loose flocking" behavior as piebaldism is linked to other flight or highly 
exciteable behavior?  Is depigmentation linked to domestication?  Are 
piebaldism and depigmentation linked?  (Dog and cat breeders, cattle and pig 
breeders, rabbit, chicken and turkey breeders may have some insights to offer 
).  I am not aware of anything done with sheep and goats except the general 
Jacob sheep color/spotting genetics of greying, freckling, ticking and lilacs.

Last year an Alabama Jacob breeder said that 90% of their Jacob lamb crop was 
blue eyed, many had black keratin hooves but more than half were extremely 
piebald.  Some Jacob breeders have one or two "blue eyes".  Are blue eyes a 
depigmentaion issue or a piebald gene issue or what?  Is there any 
association between lilac color and blue eyes?  

A few breeders have suggested that "blue eyes" are a trait to be desired ... 
but why select for blue eyes?   Events have reasons.  Are blue eyes a 
manifestation of a compromised dominant black? weak "pigmentation" cells? 
overactive piebald?  There may be a complex interaction between traits that, 
on their face, may not appear to be related.  Breeders that are selecting for 
blue eyes may have some insight into why they are selecting for this trait 
... the question should be considered in terms of cause and effect, not 
"registered" or not.  

An aside.  Are "blue eyes" related to changes in behavior?  There is 
literature that suggests depigmentation e.g., blue eyes, might be linked to 
nervous system problems, deafness, hyperactivity.   (Genetics and the 
Behavior of Domestic Animals, Temple Grandin).  Does this suggest a caution 
for Jacob sheep?  Perhaps. 

Fred Horak