In the fancy
of breeding animals and birds to a specified visual show standard,
the breeder quite often attempts to create a look by breeding related
individuals in a scheme called inbreeding or line breeding. Inbreeding
animals carries with it a breeder responsibility that is very often
not understood. Inbreeding is a breeding tool that carries with it
an often-unseen cost. This cost is often worth the price but not always.
Inbreeding moves the animals from a heterozygous or unrelated state
toward a homozygous or related state. Moving toward a homozygous state
means that more and more of the gene pairs in the chromosomes be matched.
Having matched pairs does two things. The first is to expose most
of the recessive genes in the gene pool that can actually serve to
fix and improve type through selection. The second is to reduce the
genetic choices in the growth process so that the line or breed looses
vigor. Close or constant inbreeding always has the cost of compromising
the immune system by reducing the genetic options of the immune system.
While at the same time facilitating the production absolutely gorgeous
animals that eventually will not necessarily reproduce.
Inbreeding
is not just breeding within a small selected group like a breed or
a stud. It is selecting breeding pairs that are more closely related
than the norm in the population. If the average relatedness in the
stud or line in question is second cousins and your breeding pair
is third cousins, you are not inbreeding with that pair. Relatedness
is generally specified by an inbreeding coefficient not by cousins.
The calculation of this coefficient is unfortunately beyond the capability
of most fanciers and would be a great next step to upgrade lineage
software packages to calculate this coefficient. For those who are
interested in pursuing a relatedness analysis, please do a Google
search for Wright’s Inbreeding Coefficient on the Internet and find
free software to help your efforts.
Line breeding is the dance that
experienced breeders perform to stamp the desired characteristics
of outstanding individuals on their progeny while minimizing the damage
to the immune system of the breeding birds. Most good breeders don’t
really distinguish this process but are so intuitive and observant
that their dance within the constraints of nature can have amazing
results in competent hands. While technically speaking line breeding
is also inbreeding, the selected pairs are rarely more closely related
than second cousins where outright inbreeding would involve father/granddaughter
relationships.
One useful tip that falls out of these observations
is that if you do not have a truly outstanding prepotent individual,
inbreeding a line of animals is at best a guarantee of mediocrity.
Novices beware!! No working breed of farm animal has ever been improved
by inbreeding. Inbreeding with appropriate selection produces pretty,
predictable looking/behaving animals with comparatively reduced growth
and birth rates.
If overly inbred animals will still breed,
the negative effects of the inbreeding can be “reversed” by out-crossing to
an unrelated individual; however, out-crossing too far away genetically
can also reverse all the years of creating the look. For example,
crossing a line of pure-bred exhibition budgies back to wild type
would take 7 to 9 generations to recover the look. This process was
a recommended procedure in texts written in the 1930’s. An indication
of how far we have diverged from the wild norm in the past seventy
years. This out-cross is an example of out-breeding suppression. Dealing
with a double dominant gene for wild-type smallness rather like the
process of breeding normals out of single and double-factored spangle,
single and double-factored dominant pied, crested stock. 12.5% of
the second-generation progeny are useful to make genetic progress
if one makes the correct selections. Not a trivial task.
A usefulunrelated individual is defined as a pure-bred who has no common ancestors
for at least five generations. Going back five generations means that
we are going outside the gene pool of the 64 individuals who comprise
that generation. This mating reduces Wright’s Inbreeding Coefficient
to zero in a single stroke.
Without a published pedigree, this is
an amazingly difficult selection in a small fancy. If the unrelated
individual has a common ancestor, the line may end up being worse
off and see no heterosis or hybrid vigor out of the pairing. This
may be a time when exhibition budgies imported from other countries
where importation is not routinely done may work wonderfully to revive
“tired” breeding lines. These potential outcross birds are likely
to have similar but not identical sets of recessive genes, as only
half dozen breeders at a single starting point did the development
of the modern exhibition budgerigar. Unless you select your out-cross
very carefully, the results will probably not suite the show breeder
at all in the first generation. Using two or three outcross pairs,
then interbreeding those progeny should, if you are selective, produce
individuals closer to the look. Secretariat, possibly the most magnificent
Thoroughbred ever, was the product of an outcross (in a very tight
gene pool) and he disappointed his syndicate owners, as his progeny
never performed as well as he did. This “disruption” can happen
to any breeding line if the out-cross does not appear to meld, but
in the long term these first and second generation outcross animals
are worth their weight in gold as stress reducers to the serious breeder
who has kept records. If patience is not your virtue, test mating
several candidates to determine compatibility would be prudent if
the source of your original breeding line is not still available.
In
stating the effects of these breeding protocols: inbreeding, line-breeding,
out-breeding, or out-crossing, I am assuming that the breeder is performing
a ruthless selection of their breeding stock. Selections of all substandard
individuals, who do not contribute to creating the look, are eliminated
from the breeding pool. Inbreeding alone will always result in disaster.
Inbreeding with selection is a whole different ball game. The weakness
in inbreeding with selection is our ability to distinguish selections.
Specifically, if individuals whose immune system is noticeably compromised
are used to breed, the breeding line will fail far sooner as the undesirable
genes are being paired at a greater rate and the immune system will
have far fewer tactical options to fight new infections, resist tumors,
etc. If rigorous selection is offensive to any one, I would suggest
that they not be involved in animal breeding.
The breeder must
make many selections that serve to focus and concentrate the gene
pool to create a look. This practice can be a very rewarding and productive
procedure provided that the breeder is ruthless in his selection of
his pairs. Many breeders choose not to finance the cost of rigorous
selection and the undesirable recessive genes that accompany the desirable
genes do actually overwhelm these gorgeous creatures. Hence the litany
in the fancy that the best show birds never breed. We have all heard
about feather dusters, long feathers and feather cysts but less romantic
genes enable lines that are susceptible to canker infections, temperaments
that routinely ravage youngsters, youngsters that die mysteriously
in the nest and large birds with weakened hearts, fatty tumors etc.
Those breeders who are the most uncompromising and ruthless in their
selection while creating the look become well known and can charge
hundreds perhaps thousands of dollars for their superior stock to
a willing market especially if we throw in a little marketing.
I
have never read a detailed description of the dance successful breeders
perform in creating a super prepotent line of birds. I suspect that
this process is so intuitive to the really good breeders that they
are simply not aware of the amount of detailed information they are
processing to make pair selection. Some of the issues a competent
breeder wrestles with involve interacting with the Ideal or Standard
that he is breeding for, to restore missing characteristics or pieces as
they are referred to in the budgie texts. Inbreeding reduces choices.
If apiece is missing from a line, inbreeding can never create it.
Numerous other issues that require generations of record keeping to
realize, such as resistance to weather changes, fertility, general
robustness, feather type, and color would be high on their list also.
DNA testing will be a required tool to facilitate advanced breeders
efforts to weed out feather dusters, feather cysts and other maladies
that plague current efforts to advance the look using doubled up high-buff
breeders. The Budgerigar Fancy may be too small to support the development
economics of these critical tools?
Using foster parents can be
an effective tool to increase production but their indiscriminant
use opens the door to propagating weak lines that will never improve
the flock. I would use foster parents carefully to take stress off
important hens or to save a clutch if the hen dies. Record keeping
is essential to determine if you are indeed creating a long-term problem
by solving the immediate problem of saving chicks that will not feed
as parents or worse yet have a genetically controlled chemical imbalance
that destroys the desires of motherhood.
In the process of developing
the Exhibition Budgerigar we have lost much of the natural desert
adaptation features of this bird. Specifically, the Exhibition Budgerigar
cannot be deprived of water like their wild counter parts. This is
not a big deal in captivity, except consider the stress generated
by a participation in a two-day show on our best, most vulnerable
birds if they are not served water. This seemingly minor change in
water management causes me to wonder what else has been lost or modified
in the budgerigar metabolism in the quest for unnatural size, long
feathers and a large head. An interesting example of inadvertent selection
in farm animals is that all sheep selected for better wool production
have lost the wild type ability to ovulate several times per year.
Agribusiness, not to be deprived, responded by selecting for the ability
to have twins and inadvertently selected for the genes that facilitate
triplets. Most modern domestic sheep cannot give birth without human
assistance because of their large size and the complications of multiple
births.
Separate from the concerns of inbreeding, out-breeding
etc but colliding with them is that the selection pressures required
to conform to the current “Ultimate Show Bird” has been skirting genetic
disaster. This is the history of a small group of breeders developing
competitive show birds during the War years by using a mutation calledLong-flighted. These mutation birds or freaks in their original form
were effectively banned from shows in the UK in 1951 by limiting the
maximum total length to eight and one half inches and maximum wing
length to three and three quarter inches in exhibition birds.
Our
forefathers talked of the wise, skillful use of freaks to develop
the longer feathers and larger skeleton of the modern show bird. This
said another way is that the half dozen or so breeders who had access
to long-flight crosses during the Second World War skillfully inbred
and selected for some of the recessive genes and not others that comprised
the long-flight mutation. An amusing description of this situation
by the breeder Harry Bryan as related by Roy Stringer is that skillful
breeders used a bird that could only fly backwards to make forward
progress in developing today’s exhibition birds.
There are a
couple of variations in this story as recorded but the noted differences
do not change the basic situation of an entire fancy being regenerated
from one or two mutated cocks in the hands of fancier Ken Farmer.
By his own admission, he was a man fascinated by the development ofBig Heads in the budgerigar. This is a classic description of how
the quest of selecting for extreme recessive genes increased the Genetic
Stress in even the best selective breeding program. Stress reduction
programs in other areas such as environmental and dietary improvements
must compensate for this increased Genetic Stress, as the Ideal Show
Models show no sign of moving to a smaller bird. The Exhibition Budgerigar
is a pure-bred, inbred variety necessitated by the number of recessive
genes now involved in its make up.
Show birds and breeding stock
must be selected and be kept fit to perform but breeding Exhibition
Budgerigars is not the survival of the fittest. Selecting for the
attributes of larger skeleton, longer feathers and directional feathering
has cost the budgerigar considerable vigor, compared to the earlier
racy birds of the ‘30’s. To the point where, the really good show
bird is quite a challenge to breed. Stress reduction improvements
to facilitate the survival of exaggerated show specimens might logically
be:
1) Smaller flight cages with extended use of ramps to lower activity
requirements when needed for molting birds etc,
2) Much lower population
densities in flight cages with higher segregation of ages and sexes
to reduce the effects of competition,
3) Aggressive implementation
of feeding foods rich in lysine, methionine and arginine, amino acids
used in making feathers, to support the much-desired, exaggerated,
luxuriant plumage.
4) Development of diets that support fitness at
lower activity levels recognizing that the skillfully developed, short
lived, “child of a freak” of today probably has a vastly different
metabolism and resulting dietary requirements from the smaller, faster
more energetic bird of sixty or seventy years ago.
This is a
very tall order for a fancy guided by tradition and in which the most
read book on the subject is 68 to 20 years old, depending on the edition,
which by the way has nothing good to say about Long-flights in any
edition. W. Watmough can be quoted as saying: ”Those who pursue it
(improvement by breeding Long-flights) overlook the fact that the
evil effects of using these abnormal Budgerigars will sooner or later
be seen.” I don’t really agree that the effects of our forefathers
breeding efforts are evil but their efforts have added considerable
cumulative stress to the overall picture of producing and keeping
Exhibition Budgerigars. It is paramount that these effects be considered
in the design of any successful breeding program. It is also important
that the committees and judges who define the ideal Exhibition Budgerigar
be responsible for the well being of those birds by not straying too
far away from the natural blueprint. Choosing a standard that increases
the number of recessive genes being selected for will automatically
decrease the health of those birds due to unavoidable, accompanying
genetic uniformity that increases the possibility of immune system
failure.
I have overheard conversations bemoaning the fact that
the rate of occurrence of new color mutations in captive budgerigars
has declined markedly. The inbreeding done to create the modern exhibition
budgerigar has thrown away most of the rare genes. Our line-breeding
for type eliminates most rare color genes from the stud forever. Watch
for new colors in the aviaries of pet budgerigar breeders not exhibition
type birds. Bringing a new or rare color up in the face of out-breeding
suppression of exhibition standards is a 7 to 10 year project with
setbacks and no short cuts. As a fancy in our impatient modern society
are we up to it?
To review the distinctions created:
Inbreeding is
a process by which the genetic variability in a pure-bred stud is
reduced for the purpose of producing uniformity.
Close-breeding is
the extreme form of inbreeding, often a detrimental process of mating
siblings and parents to quickly expose hidden gene types that an individual
carries, such as is done in developing a new color mutation.
Out-breeding is
a process by which the genetic variability in a stud is maintained
or increased by selectively introducing pure-bred breeding partners
who are less closely related than the norm for the stud.
Pure-breeding is
a process by which recessive varieties like the Exhibition Budgerigar
are maintained by breeding pairs, where both partners look like what
is generally accepted to be an Exhibition Budgerigar. This is called
being Purebred especially when the visual uniformity has gone on for
at least three generations. The use of the term “pure” in a genetic
reference is unfortunate as by their nature genes are diverse or dead,
never pure.
Out-crossing is a process by which a pure-bred individual
or group of individuals with no common ancestor for five generations
is introduced into a pure-bred, in-bred stud for the purpose of increasing
genetic variability.
Line-breeding is a dance within the constraints
of nature where inbreeding and out-breeding are combined in a pure-bred
stud to promote a look engendered by a Prepotent Individual while
hopefully avoiding the pitfalls of reduced genetic diversity of close-breeding.
Hybridization is
a process by which the wild-type or another species entirely is bred
into a pure-bred stud creating heterosis with the likelihood of heterosis being
combined with out-breeding suppression.
Out-breeding suppression occurs
when the out-cross chosen has antagonistic dominant genes to the ones
desired.
Out-breeding enhancement or Heterosis occurs when an in-bred
line is out-crossed. This is another name for hybrid vigor.
Heterozygous is a term describing the state of inheriting different
genes for a particular trait from each parent thus suppressing the
recessive gene.
Homozygous is a term describing the state of inheriting
the same gene for a particular trait from each parent thus revealing
the recessive gene.