Challenging
the popular viewpoints on computer matings to avoid pedigree inbreeding
During the dynamic
years of building high production dairy herds utilizing the higher ranking of
high reliability evaluation of progeny across a diversity of herd environments,
a small handful of 1960s sires came to dominate each breed. Most notably, in Ayrshires it
was Selwood Betty’s Commander:
in Brown Swiss it was Welcome In Stretch: in Jerseys it was Observer
Chocolate Soldier (often in
combination with his half brother, SS Quicksilver of Fallneva): in Guernseys it was Maurana
Wis Telestar: finally, in Holsteins
it was that duo of Round
Oak R. A. Elevation crossed with Pawnee Farm Arlinda Chief. (Many thought Carlin M Ivanhoe Bell as
a leader in protein yields would eclipse them, but thanks to the “BLAD” and
“CVM” recessives showing up as he was linebred against other “Ivanhoe”
descendants, his pedigree influence waned.)
What these
sires had in common was an ability to produce offspring that transitioned
dairying from milking “hay burners” into today’s expansion dairy focus on corn
silage forage and oilseed proteins.
Today, whether you look at Breed Association pedigree studies or the DNA
genotype patterns, a full 25% of the modern Jersey genotype comes from
“Chocolate Soldier” (and note he spread the lethal recessive for early-term
abortion, JH1C, to a quarter of all Jerseys) and in the
world-dominating Holstein breed, 30% of the Black and White genotype comes from
those two 1960s bulls “Elevation” and “Arlinda Chief”.
What
made these two bulls take over the Holstein breeding world?
My personal prejudice is that each sire was bred within herds that considered
the “aAa” (Weeks Analysis) Breeding Guide. These two bulls were magnificent physical
specimens expressing an exceptional degree of phenotypic “balance”
(Chief, born 1962, eventually classified
“EX” at 94 points while Elevation, born 1965, eventually classified “EX”
at 96 points) and this enabled them to both live functionally to 14
years of age, thus producing large volumes of semen. Their most notable recent descendant, Picston Shottle (a key influence within the Holstein Genomic/
DNA “reference population”) had a similar 16 year life span at his AI stud
residence in England. The biggest
“secret” in dairy cattle breeding is that “aAa” exerts more influence on
breeding cows that will reach a productive maturity than any other
promoted approach to matings.
As Genomic
selection approaches have advanced, the frequency of “Arlinda Chief” genes also
advances. Comparing “Arlinda Chief”
to “Elevation”, you have a truly linebred bull in “Chief” (eight
close crosses to ABC Reflection Sovereign *RC; over 20 crosses to the originating bull of
the “Rag Apple” bloodline, Johanna Rag Apple Pabst) – while you have an
example of the old practice of line crossing in “Elevation” (his sire an inbred son of linebred Wis
Burke Ideal; his dam a linebred
descendant of Johanna Rag Apple Pabst with NO ancestry
from the mentioned ABC Reflection Sovereign *RC so important in “Arlinda
Chief”s “Rag Apple” heritage).
Outcrossing
within a breed generates similar heterosis (“hybrid vigor”) as crossbreeding.
When you cross a linebred bull with the equally linebred descendants of another
linebred bull, but with those two sires appearing to be “outcross” to each
other, you can generate a “hybrid vigor” response in purebred matings that is
often as powerful as the first cross results from a “crossbreeding”
scheme. In fact, as far as Holstein
breed progress since frozen semen came on the scene allowed better linebred
bulls access to unrelated cows across the country (1955 in Ontario, 1957 at
ABS, 1959 at Curtiss, 1963 at Carnation) the casual pedigree relationships in
AI service produced a rising “inbreeding coefficient”. Some University extension people became
concerned, taught their captive state AI cooperatives to preach against
“inbreeding”, and the result was a demand for AI mating services to consider
inbreeding in mating suggestions. So we
might ask—how successful was this focus?
Dr Les Hanson of University of Minnesota is an example of a
geneticist who predicted “the Holstein breed is getting so inbred that it could
be obsolete in 10 years—the only solution will be to crossbreed” (which
resulted in the “Pro Cross” concept promoted until recently from southern
California). He made this prediction
over 30 years ago, but in spite of increasing efi% across commercial dairies,
the Holstein still survives.
With Genomic
mating selection, however, today’s sire offerings differ from what most
AI studs offered between 1960 (when lots of bloodlines were represented) and
2000 (when sire lines were down to Ivanhoe (mostly through “Bell”), Arlinda
Chief and Elevation. The “heterosis”
remaining in Holsteins came from the diversity of cow lines competing for
AI attention. It was also true that a plurality of the more
successful breeders of AI stud bulls followed “aAa” matings in which the Breeding
Guide avoids the mating of “likes to likes” at the level of physical
genes. Thus these donor cows who
produced successful sons retained outcross vigor against the AI-generated
mating sires who were increasingly sire line concentrations.
Farnear
Delta Lambda (late of ST Genetics) is a textbook example of Genomic
matings
This bull
recently died at the point where his oldest daughters were first calving. He follows a pattern among the Genomic
success stories—( McCutcheon, Mogul, now Lambda ) – unable to live a full
productive life. Why do these sires
expire so much younger than the more famous of their progenitors? Perhaps all this emphasis on “fast
maturity” genetics is mainly giving us an “accelerated aging” of their
physiques??
“Lambda”
has 50 pedigree crosses to SWD Valiant, perhaps the most revered of the early sons of Pawnee Farm
Arlinda Chief. “Lambda also
has 25 crosses to Walkway Chief Mark, perhaps the last of the successful
sons of Pawnee Farm Arlinda Chief.
Both “Valiant” and “Chief Mark” were pedigree outcrosses
to Round Oak Rag Apple Elevation.
They both had “round” (code 4 aAa) front ends, but were otherwise “sharp” (code 2
bodies and udders, code 3 rear ends) in
physical expression, relating to qualities that can use a corn-oilseed based
ration to make milk. You
will find similar concentrations of blood to various high profile bull
ancestors in the noted Genomic “success stories”. So
why do these bull studs caution you to avoid “inbreeding” seeing they
are so enthusiastically following the practice themselves??