RE: RE: Karahty (and Bloodlines in Arabs)

["Bob Morris" <bobmorris@rmci.net>]

As I have stated before, this study was done as a blind (no names ) study of
the progenitors of those Arabs with available AERC and AHR  registration
#'s. We did not look for any thing in particular, we let the numbers fall
where they may and we restricted ourselves to a manageable size of
investigation. If any one has a desire for more particular information or
wants to dispute what Salim has put on line, then I suggest that funding be
arranged for as we have invested a fair amount of our own time and money in
what you have seen.

Bob Morris

-----Original Message-----
From: CMKSAGEHIL@aol.com [mailto:CMKSAGEHIL@aol.com]
Sent: Thursday, April 20, 2000 1:51 PM
To: bobmorris@rmci.net; katswig@earthlink.net
Cc: ridecamp@endurance.net
Subject: RC: RE: Karahty (and Bloodlines in Arabs)


In a message dated 4/20/00 9:32:18 AM Pacific Daylight Time,
bobmorris@rmci.net writes:

<< Realize we only went back five generations as anything further does not
have
 immediate influence on performance. >>

That's only true when you are dealing with a diverse group of ancestors.
The
vast majority of the horses that came up repeatedly in your study are
actually quite closely related, which becomes obvious going back just a few
more generations.  One stallion in particular (Mesaoud) often does not
appear
in modern pedigrees until one goes back 7 or 8 generations, but appears
literally hundreds of times, so actually makes up a very high percentage of
the pedigree.  I was shocked when I counted the number of times he appeared
in the pedigrees of my own stallions, and then calculated the actual
percentages of their pedigrees that he represents--it ranged from a low of
12.4% to a high of 19.8%.  Furthermore (reference geneticists Michael and
Ann
Bowling for explanation if you don't grasp this), an individual has far more
influence on a pedigree by appearing multiple times several generations back
than he or she does by appearing fewer times up close (if he is represented
by different ones of his offspring) because each different offspring has a
different subset of the genes of that particular ancestor.  Mesaoud, for
instance, appears in pedigrees in my own herd through over 20 of his
offspring--each of which represents a "unique" half of his genetic material.
(And my group is fairly representative of the Mesaoud influence in North
America, I might add.)  To look at a more recent example of representing a
particular ancestor--we've tried to represent Abu Farwa (among several other
ancestors) in our program, and although since he is more modern than
Mesaoud,
it is difficult to find such a spread in one pedigree, he occurs through 24
different offspring in our program.  In another 3 or 4 generations, he could
well appear much the way that Mesaoud does in the current pedigrees.  Does
that mean he would no longer be an influence?  Hardly!

The current study under discussion is interesting, but as Kris pointed out
(and Salim concurred) it does not ask specific questions.  And as others
have
pointed out, it does not delineate possible differences between successful
endurance horses and the North American gene pool at large.  Michael Bowling
has done a random sample of relatively current stud books which he has used
for several studies--it would be interesting to look at this list in context
of that random sample, for instance.

Heidi


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