[Jacob-list] Early greying

[Jacobflock at aol.com]

Grey haired Fred Horak here.  These are neat observations on grey sheep and 
non-grey sheep.  I ask indulgence on adding to this observation with three 
messages: the "greying" gene is dominant, the Ticking gene is similar, the 
observations reveals the sire and dam genotypes, observations of this nature 
are important for the breeder and breed.  

If you have a Jacob that tends to grey at one to two years of age, whether 
ram or ewe...either ram or ewe...and suppose they are bred (thats the reason 
I changed from "whether" ram to "either" ram..), the phenotype you see (the 
early greying gene G), must be in the genotype at least as a Gg 
(heterozygous) but may be a (homozygous) GG.  The non-grey is a recessive gg.

Because it is dominant you see it whether the genotype is Gg or GG.  One can 
change the genotype of the Jacob by purposely using and promoting the greying 
(spinners may like this) or by accident (the use of a Gg or GG ram lamb over 
the flock and producing a crop of Gg and GG Jacobs).

If you wish to get rid of the premature graying before the trait is "fixed" 
in the flock or the breed (the whole  flock and breed become GG), steps would 
have to be taken to retain  the Gg or conserve the recessive gg.  

Using heterozygous parents, the chances of retaining the Gg is 1/2 and the 
chances for conserving the "non-graying" homozygous gg is 1/4 (GG, 2Gg, gg).  
Chances improve for non-greys to 1/2 for a Gg to a gg (2Gg, 2gg).   The odds 
are on our side that there will be a ram and ewe with the recessive 
non-greying gene; i.e., heterozygous.  However, "fixing the greying trait" is 
also possible by purposeful selection or not being aware; you can not get a 
non-grey from a flock or breed of homozygous (GG) gray Jacobs.  

Ticking is the appearance of spots over time from areas that were clear in 
the birth lamb fleece.  The "freckles" that appear from nowhere is Ticking. 
The Ticking gene and Graying gene are dominant and operate in a similar 
manner.  You can substitute T's for G's for the two phenotypes and three 
geneotypes. 

The observation of early graying and and observations of ticking in parents 
and the progeny ratios (as described in the other posts) is the evidence of 
the genotype of the sire and dam.  

The "breed" questions then follow...should the Breed Standard for the Jacob 
be changed to include the dominant greying genotype?  (ala the recessive 
"lilac")... or does one wait until the genotype is expressed before 
registering (ala appearance of true horns vs. aberrant horns or scurs in 
ewes) ..or add longitudinal registry data to reflect these changes over 
time?...or does it even matter?

The practical "breeder" question might be...Do I breed lambs at 6 months that 
have not yet revealed their phenotype/genotype... or breed unaware of the 
parents genotype (phenotype  and pedigree information)?...or just ignore the 
question because of my environment (space, time, cost) ?

Wandering mind question: Are birth freckles recessive?...By birth freckles I 
mean the little "pencil eraser head" spots present in the brith fleece (as 
opposed to ticking); the incomplete closure of the recessive piebald on the 
dominant black.  Ticking and freckles can be present in the same dermis.  
Does one get "birth freckles" from clear parents?  Are Ticking and Birth 
Freckles linked?

Some breeders want to buy "a homozygous Jacob" lamb that doesn't grey, 
doesn't have birth freckles, doesn't get freckles, with four perfectly 
balanced and separated horns and a 'primitive" look'", four inch fleece, 
crimped, micron with minimal deviation, low mangement and attendent protein 
demand, good mothering, only produces twin ewes, parasite tolerant, disease 
resistant, etc.... The Jacob, first known as the Spanish sheep with four 
horns, brings to mind the Spaniard Don Quixote and the "Jacob Breeder" song 
from Man From LaMancha....download "The Impossible Dream" from Napster.

Fred