[Jacob-list] DEF:Freckling, Ticking, Mottling

[Jacobflock at aol.com]

In a message dated 4/8/02 4:29:31 PM Central Daylight Time, 
maplelanehmstd at dialpoint.net writes:


> I have some sheep that have freckles with dark wool coming from that spot 
> and also some that just have dark pigmented spots(white wool covering 
> those). I assumed all were considered freckles and have culled because of 
> it . Am I correct in my thinking?
> 

Freckles, small dark skin spots with black wool, which appear in the piebald 
area at birth, have a "black fiber producing site in the dermal layer .. deep 
down in the skin.  The dark skin that does not produce black fiber is skin 
mottling which is the presence of melanin in the epidermal layer ... top 
layer of the skin.

Ticking is the "appearance of what we like to call freckles" ... like we use 
the term "sunrise" ... which do not appear at birth but develop as a black 
"spot" (pick up your pencils please) and have a black fiber ...  and increase 
in number (and slightly in size ... pencil point to eraser) over time. Put 
down the pencils.

My concern is the "indiscriminate" breeding for these traits absent 
understanding the Spotting locus and epistatic factors ... interaction 
between genes that are not alleles.
I do not think I advocated sending them all to the knacker or sale barn ... 
it was a caution before the consequences become irrecoverable.  Fred Horak
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