A Look at Prepotent Brood Stock in ADBA History ~ Part V
by Amy Greenwood-Dudar
Thanks to all of our readers who
sent in suggestions of prepotent brood
stock to include in our retroactive study.
Those dogs will be featured in this issue
with perhaps a few left over for the next
issue. We will add these individuals to
the 30 previous dogs featured to expand
our sample size. As a general rule, the
bigger the sample size, the more validity
in a study.
As a recap for first time readers of the
Gazette, what I am doing in this series of
articles is looking at the breeding strategy
in the pedigrees of select prepotent
stud dogs and brood matrons in APBT
history. I have always enjoyed looking
at pedigrees and identifying the breeding
strategies used by breeders in the development
of their bloodline. My father,
Ralph Greenwood, was a pedigree connoisseur.
As a teenager, he would have
me write out a seven generation pedigree
by hand on every new dog that he
would get into his kennel. My brother,
Hank, had made up the pedigree template
in drafting class in high school and
Ralph made good use of these forms researching
extensive backgrounds on his
dogs as well as those of his friends. Because
of the influence of my father and
other breeders that he respected, I developed
my passion for pedigrees. Identifying
the breeding strategy contained
within each generation is akin to solving
a mystery. It is something I have the
opportunity do weekly in my role doing
pedigree analysis and bloodline identification
with the American Dog Breeders
Association.
After the breeding strategy is identified
on each dog featured, I can then
evaluate how they measure up to the genetic
basis of prepotency as proposed
in the Cynologist article that I have
referenced in my previous article in the
August 2019 issue of the Gazette. At the
conclusion, we will look at the tally of
the dogs we have highlighted and the
statistics up to that point in our study.
First some background: The term
‘prepotent’, by definition, is having ex-
4
ceptional power, authority or influence.
Applied to dog breeding, prepotency
is when a stud dog stamps his likeness
upon his offspring to a marked degree
and passes on his traits to an especially
large number of his offspring, or produce
puppies that resembles each other
more closely than usual. The term prepotent
can also apply to a brood matron
and having a dam with this quality is
valuable also. The far reaching effects
of a prepotent stud dog to the breed as a
whole is considerable, since he can produce
a larger number of offspring over
his lifetime compared to that of a dam.
Every dog breeder knows the importance
of a great sire that “throws himself”
in an individual breeding program,
as well as the far reaching influence in
the betterment of the breed as a whole.
There are three major questions with
regard to prepotency that may be of interest
to breeders.
• What is the genetic basis of prepotency?
• How can prepotency be measured?
• How can prepotent animals be produced?
The book Animal Breeding Plans
by Lush answers these questions.
Lush states that the most important
genetic basis of prepotence to a high
degree depends first upon homozygosity
and second upon dominance, linkage
and epistasis. A homozygous animal
is one which possesses the gene for a
given trait from both his sire and dam
and is genetically pure for that characteristic.
A homozygous animal can only
produce one type of germ cell (sperm
or egg) and he would pass on exactly
the same genes to all of his offspring.
A dominant gene is described as one of
a pair of alleles (alternate forms of the
same gene influencing the same trait
but in different ways) whose effect is
expressed to the exclusion of the effect
of the other alleles. Every puppy receiving
the dominant gene will show the effect
of the gene. If the gene is dominant
and the parent is homozygous for it, the
offspring will appear exactly alike for
the trait expressed by the gene, regardless
of the genetic material that they received
from the other parent. “When a
parent having many dominant genes is
also highly homozygous, it prepotency
is maximum”. (Lush)
Linked genes are those that are located
closely on the same chromosome.
Two or more characteristics are transmitted
together instead of randomly in
the usual manner. Epistasis is believed
to contribute to prepotency in some cases.
“When a gene of one pair of allelic
genes masks the expression of the genes
of another pair of allelic genes, it is said
to be epistatic to the other pair. (Snyder,
The Principals of Heredity.) Epistasis
is similar to dominance except the relationship
is between different genes,
instead of alleles on the same gene.
Measuring prepotency:
One way to measure prepotency is to
note the resemblance of sire and puppies
as compared to the resemblance
ordinarily found between parents and
offspring. When a prepotent sire is used,
the resemblance of their traits will be
greater no matter which dam is used. I
am not only talking about physical resemblance
but more importantly athleticism,
temperament and performance.
Production of prepotent animals:
Even though we see prepotent sires in
lines that are not inbred, the breeder’s
chief aid in producing a prepotent animal
is through the use of inbreeding.
The reason for this is that while dominance,
linkage and epistasis of genes
are not within the power of the breeder
to control, he can control the homozygosity
of his stock. The more closely
related the more rapid will be the increase
in homozygosity. Mating like to
like without inbreeding does little to increase
prepotency.
“The broad scientific definition is
that inbreeding is the mating of animals