[Jacob-list] Determining Purebred Traits in Jacobs Part 1 of 2

[ranchrat]

Part 1 of 2
Heel low:
There is an interesting study May 21, 2004, done on canines, link below.
What they wanted to do, more or less, was establish a genetic "makeup"
(a DNA description) for a dog breed.  Up until studies like this, you
could not look at the DNA of a canine and with any certainty, tell
whether it was a St. Bernard or a Poodle.  This was kinda strange
because up to that point, the phenotype (what it LOOKs like certainly
hinted at what breed it was), but in the genotype (the genetic make up,
what genetic material instructs the animal to appear as they do), we
were perfectly clueless.  If a baby was attacked by a "dog," and you had
a blood sample, DNA testing it would not bring you any closer to
identifying what "breed" had done the dastardly deed.  We have done some
very interesting genotyping in humans where we can take a sample and
have a pretty good idea what ancient peoples you descended from.it never
ceases to amaze me how many kewl things we are doing with DNA.
o       www.sciencemag.org/cgi/content/abstract/304/5674/1160 
The trouble I had with this dog study was that OK, you want to define a
breed.so exactly which dog/dogs is/are going to be the "perfect"
representation of a St. Bernard.one that physically fits the standard
(of which country?) 100 percent?  No such animal exists tho I am certain
many a kennel owner would have their hand raised steadily in the air,
hoping that their strain was chosen over all others.  Years back, a dog
disease text was compiled and in there they wrote in that my particular
breed (Australian Cattle Dogs) had these many breed disorders. Many of
which I do concur the breed is predisposed to succumbing to (we DNA,.
X-ray, BAER hearing test, and go to ontholmologists annually to ensure
our breeding stock does not throw these disorders in their progeny-still
happens but helps lower the risks), but in some cases, no ACDs I know of
have EVER had some of these disorders.  We found out the book was based
upon studying mixed breeds of our breed, so may have skewed the results.
I would certainly want to know which ovines were chosen in any DNA study
where they were looking to determine a marker towards "purebred" Jacobs.
So another question is that to be representational of a breed, which
animal is also suppose to be "purebred."  Since humans cannot even
guarantee who their own offspring are sired by without a DNA parentage
test, whatever makes us think we could plausibly guarantee, for
generation upon generation that a Jacob Sheep was pure.  Those ancient
park sheep ran about and who could say that a "rammy" ram of some other
breed could not have assisted those Jacob flocks along-there has to be
divergence select for from the Mouflon or we'd not have "breeds" of
domestic sheep.  We do have some good ways of detecting the F1 crossbred
Jacob (most often very black and as Neal says, "There is always
something askew with these sheep"), but what if the F1's were smart
(hybrid vigour is a plausible answer to improvements.physical and
mental) and hid out and generations covered over impurities.  Are we all
satisfied that from 1880 (why this date.dang-I've dozed off and missed
something) we're all good?
You are allowed in some registries, to breed up.this term to me means
you start off with a breed of sheep on one side of the pedigree, back
cross to the breed you want until it reaches some point of "pureness."
I can't remember the exact fraction, maybe Neal can.7/8's or was it
15/16's.some such number.  Then you were allowed to register the animal
as a certain "purebred" livestock breed.  Purebred is suppose to be
determined as replication of itself.true breeding.


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