A Look at Prepotent Brood Stock in ADBA History - Part III
In my role at the ADBA doing pedi-
gree analysis, I have the opportunity to
study pedigrees and identify the breed-
ing strategies being used by breeders of
the past and those individuals produc-
ing litters today. By dissecting a seven
generation pedigree, it is really fasci-
nating to see a glimpse into the plan-
ning behind the famous dogs of the past
and the litters being produced today.
It takes two basic principals that
breeders must consider in producing a
quality litter. #1 is the selection of qual-
ity brood stock possessing the traits that
the breeder wants to see in the litter. #2
is following a breeding plan by look-
ing at the pedigrees of those sire and
dams and determining the mating that
will give you the greatest probability of
producing those positive traits that the
breeder is attempting to produce in his
litters. The goal should be to produce
consistent and predictable traits in each
litter. It has been said that an outstand-
ing breeder is always planning ahead a
few generations. That is the challenge
and excitement of being a breeder of
outstanding dogs.
In the last issue of the American Pit
Bull Terrier Gazette, I laid the ground
work of the significance of the study of
the “prepotent” sire and dams through-
out the history of our breed. For those
first time readers of the Gazette, and
as a recap, let’s begin with the defini-
tion of Prepotent. Prepotent is defined
as having exceptional power, authority
of influence. In terms of dog breeding,
a prepotent sire or dam passes on their
traits to a large number of their off-
spring regardless to whom they were
bred. The value of both a prepotent stud
dog or brood matron can not be under-
stated, but the far reaching effects to
the breed as whole is greater in the case
of a prepotent stud dog. This is due to
the large number of offspring that can
be produced by a stud dog compared to
that of a brood matron.
A review of the literature outlined
the genetic basis of prepotence: Jay L.
4
Lush stated in his book Animal Breed-
ing Plans that the most important genet-
ic basis of prepotency depends first on
homozygosity (alleles being the same
at a given gene), then upon dominance,
linkage and epistasis. A homozygous
animal possesses the gene for a given
trait from both his sire and dam and is
genetically pure for that characteristic.
Because the gene pairs are identical,
this gene is passed on to every one of
their offspring 100% of the time.
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 over the effects of the al-
ternate alleles. Every puppy receiving
the dominant allele will show the effect
of it. If the parent is homozygous for it,
all of the offspring will be exactly alike
for the trait expressed by the gene, re-
gardless of the genetic material that
they received from the other parent.
Lush states, “When a parent having
many dominant genes is also highly
homozygous, its prepotency is MAXI-
MUM.”
Linked genes are those that are lo-
cated closely on the same chromo-
somes. Two or more characteristics are
passed on together instead of randomly
in the usual manner.
Epistasis is defined as when a gene
or a pair of allelic genes masks the
expression of a different gene or pair
of allelic genes. Epistasis is similar to
dominance except the relationship is
between different genes, instead of al-
leles on the same genes. Because of its
similarity to dominance epistasis is be-
lieved to contribute to prepotency.
Since Lush states, “The most im-
portant genetic basis of prepotence is
homozygosity” the next question to
be answered is how does the breeder
produce homozygosity in his breeding
stock?
Production of prepotent animals.
Even though we see prepotent brood
stock in lines that are not closely line
bred and inbred, the breeder’s chief
aid in producing a prepotent animal is
through the use of these breeding strat-
egies. 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 sire and dam, the
more rapid will be the increase in ho-
mozygosity. Mating like to like without
inbreeding and line breeding does little
to increase prepotency.
“The broad scientific definition is
that inbreeding is the mating of animals
more closely related to each other than
the average relationship of the popula-
tion concerned. When done properly
and wisely it is of great assistance and
using inbreeding vigorous prepotent
animals of correct type are more rap-
idly produced.” (Lush) Because of this
statement, I believe that Lush is lump-
ing styles of line breeding together with
classic styles of inbreeding and refers
to them all as inbreeding. He states that
the mating of brother to sister is the
highest form of inbreeding.
Contrary to what most people believe
because of the political hype against
breeders, inbreeding and close line
breeding does not create any weakness,
defects or any of the physical or mental
traits which will disqualify a dog from
fulfilling its function. Inbreeding mere-
ly exposes hidden recessive genes that
have been present in the stock all along
under the shield of their dominant al-
leles. It does this by presenting them
in a homozygous condition so they are
expressed and made visible. By using
inbreeding, the breeder is given an op-
portunity to discover exactly what he-
redity traits are carried by his animals.
By bringing them to light, in some cas-
es, he can completely remove from his
bloodline those individuals that prove
to be undesirable. A humane breeder
can do this by spaying and neutering
and placing in pet homes those dogs
not acceptable as breeding stock. Ge-