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Breeding true to type – Breeding true to the breed

A very liberally edited version of an article by Jerold S. Bell, D.V.M. that appeared in the September 1992 American Kennel Club Gazette,  “The Ins and Outs of Pedigree Analysis, Genetic Diversity, and Genetic Disease Control”
The Blue Lacy is a mid sized dog that comes to your knee. Very sleek with the look of a small Greyhound and the build for speed and endurance they are noted for. The true American Blue Lacy is so intelligent, you show them something once or twice and it’s already learned. They instinctively know how to work and know what you want. There is no such thing as a Blue Lacy that doesn’t have an incredible nose for tracking. If this doesn’t describe your Blue Lacy, perhaps you would be right to question whether it is a purebred Blue Lacy.
Without exception all breeds of dogs are the result of inbreeding.  Inbreeding has either occurred through natural selection among a small isolated population (i.e. the dingo) or through the influence of man breeding selected animals to derive specific traits.  Either way intensive inbreeding is responsible for setting enough of the dominant traits that the resulting group breeds true to type.  At which point a population of dogs can be said to be a breed.
Linebreeding concentrates the genes of a specific ancestor or ancestors through their appearance multiple times in a pedigree.   When a specific ancestor appears more than once behind at least one animal on both the sire’s side and yet another animal on the dame’s side homozygosity for that animal’s traits are possible.
However, if this specific ancestor appears only through a particular offspring of the ancestor in question then the Breeder is actually breeding on this offspring of the ancestor rather than on the ancestor itself.  This is why having many “uncovered crosses” to a specific ancestor ( those that come through different offspring of this specific ancestor) gives the Breeder the greatest chance of making the desired traits of the specific ancestor homozygous.
Homozygosity greatly improves the chances that the resulting pups will in turn pass on the desired traits of the specific ancestor to their pups.  When selecting pups from a line breed litter the Breeder must choose pups that display the desired traits of the specific ancestor or they have accomplished little.   In fact, if these traits are not present in a linebred pup it is very likely that it inherited its genes from the remaining part of its pedigree and will be unable to breed true to type. Because the Breeder selected “out” for the pups that didn’t display this original ancestor’s traits.
Inbreeding significantly increases homozygosity, and therefore uniformity within a litter.  One of the best methods of evaluating how successful a linebreeding has been is to gauge the similarity of the littermates as compared with pups of other litters with similar pedigrees.   Considerable similarity among littermates tells the Breeder the genes have “nicked” or paired together as anticipated.  The resulting pups will likely be able to pass these genes to the next generation.
Too many Breeders outcross as soon as an undesirable trait appears, blaming the problem on breeding “too close.”  Nothing could be further from the truth.  In fact out-crossing insures that the undesirable trait will be carried generation after generation in a heterozygous recessive state only to rear its ugly head again and again. Therefore the Breeder who turns away from breeding “close” is simply passing a known problem on to succeeding generations and future Breeders.
When an undesirable trait is “unmasked” the Breeder who does his breed a real service is the one that stays with his line long enough to rid it of the undesirable trait.  By controlling which specimens within their line are used for breeding in succeeding generations this Breeder can eliminate the undesirable trait.  Once the recessive gene is removed it can never again affect the Breeder’s line. Inbreeding doesn’t cause good genes to mutate into bad genes it merely increases the likelihood that they will be displayed.
The Inbreeding Coefficient (or Wrights coefficient) is an estimate of the percentage of all variable genes that are homozygous due to inheritance from common ancestors.  It is also the average chance that any single gene pair is homozygous due to inheritance from a common ancestor.  Our pedigrees display the Inbreeding Coefficient for each dog in the first 4 generations of a specific dog’s ancestry.   Each Inbreeding Coefficient is calculated from that dog’s 10 generation pedigree.
On more than one occasion we have seen pedigrees in which the most influential ancestor for a homozygous trait doesn’t even appear in the first three generations.  In this type of situation it is not unusual for this particular ancestor to contribute 50% of the homozygous genes of the dog in question.  In this case if a dog is 16% inbred one ancestor would be responsible for 8% or 50% of the dogs homozygosity. It is of paramount importance for the dedicated Breeder to know not only the inbreeding coefficient for the resulting litter  before the mating is done but also which dogs in the pups pedigree are influencing their genetic potential.

Far too many matings have been done only on the basis of physical appearance with little if any regard to the sire’s and dame’s respective pedigrees or the interplay between the two.  Novice Breeders don’t realize that individual dogs may share desirable traits but inherit them differently.  This is especially true of polygenic traits, such as ear set, bite, or length of forearm.  And many Breeders fail to understand that breeding dogs which are phenotypically similar but genotypically unrelated won’t produce the desired traits in the current litter – and will actually reduce the chance of these traits being reproducible in the next generation.

The secret is that all linebreedings must be made on a combination of performance, appearance and ancestry.  If a Breeder is going to be successful in solidifying a certain trait they must rigorously select breeding specimens which display the desired trait and have similar pedigrees. In so doing Breeders have a chance of making this desired trait homozygous over time.  This is the one key to successful linebreeding that is most often missed by unsuccessful Breeders.
The bitches are far more important than the studs in carrying particular genes forward.  Understand that this is true even if the genes most sought were originally found in a pre-potent male.  The key for any successful Breeder is to isolate those females that carried his traits and breed off of them.  It has been our experience that many important traits are indeed sex linked and carried by the dames from generation to generation.

Successful Breeders realize they are fighting “the drag of the breed,” which is the tendency for all animals to breed back toward mediocrity. If it didn’t work this way super species and super races would have developed long ago in every animal on earth.  For instance in human beings it is impossible to breed parents with high IQs together to produce higher IQs. Even when two genius have children the average IQ of their children will be half way between normal and the average of their IQs.

By the way Einstein himself was the off spring of  parents who were themselves first cousins – and he married his first cousin.  So much for the tails of woe you heard in school about the effects of inbreeding.
In fact what few people understand actually happens is that as a line is successfully bred over the years a concentration of good recessive genes is happening.  Assuming the Breeder is a person of integrity and doesn’t knowingly breed animals that have disqualifiable faults or traits.  Over a period of time this Breeder will clean up his genepool.  While it is true that linebreeding gives the opportunity for the worst traits to display themselves in any  individual animal, it is not true that the Breeder is required to use that animal in his genepool.  In fact if the Breeder is concerned with his genepool and not just about producing pups he actually has the opportunity to clean up genes that would go unnoticed in an outcross breeding.
So what is the answer?  Wherein lies the truth?  It is not what you want to hear but here it is: Years and years of line breeding by a committed ethical Breeder – someone with a vision of perfection and the tenacity to make difficult decisions.  The only way to consistently produce superior animals is to linebred.  Period … it’s that simple!
:roll: :roll: :roll:
To them, and to you, we pose this question: “If out-cross breeding is the answer then why don’t the owners of successful herds of Holstein milk cows out-cross to the American Shorthorn milk cow?”  In theory this would produce super milk cows by combining a milk cow that has the genes for high milk production like the Holstein with one that has the genes for high milk quality like the American Shorthorn.  Oh yes on both paper (the stuff of academia) and in theory this should produce the best milk cows on earth.
But this is where the theory that reigns supreme in the professor’s lab meets the reality of the milk barn.  Some of the most inbred animals on the face of the earth are Holstein Cattle.  The reality is that dairy farmers know all too well is that they would go broke from the inferior milk production of the resulting out-crossed animals.  Crossing to an animal with such poor milk production would be disastrous fore them. And here in lies the rub for all of us …
Understand something and don’t let anyone sway you again. Outcrossing does NOT produce “more” – the genetic material remains the same.  Nor do the qualities of the subject animals it produces multiply.  Just as linebreeding doesn’t damage genes – outcrossing doesn’t magnify what’s in the genome. There is no magic in out crossing!
And for those who continue to stubbornly advocate outcrossing we ask you this final question:  “Even if by random chance the outcross breeding in question would actually  produce a superior specimen would the animal in question be able to reproduce itself?  Would the greatness be passed on to its get?”  No.
The sad fact is that this superior specimen would likely not be able to reproduce itself.  It will likely never throw a single specimen as good as it is in its lifetime.  This is because by definition this “super specimen” is of the F1 generation. And animals of this generation are rarely able to reproduce themselves.  So what has been accomplished by even a successful outcross?  Little or nothing other than to put a single animal on the ground.
For fun I would like to invite this no-nothing college professor to the race track where for an afternoon he would have the opportunity to bet on all the outcrosses and I would bet on all the linebred race horses.  I believe we call them Thoroughbreds for a reason don’t we?  Oh but I forgot he wouldn’t be the betting kind would he?  Not in his lifestyle and not in his career.  No, he would be the man of theory.  He would be a man who lives in the world of theory.
Not us my friend!  No, we both live in the world of fact.  Yes, we live in the world of tracking and hunting where what separates the wheat from the chafe are immeasurable traits like “heart” and “tracking sense”.  As American Blue Lacy breeders we understand how much is expected of these amazing athletes we call American Blue Lacys.  You see we own performance animals not lab rats.
Think about it.  Those who advocate the outcrossing of hunting dogs are effectively proposing that hunters entrust the development of their performance dogs to the whims of random chance.  If you believe this is a wise course then you need to locate another Breeder.  May we suggest that you check the want ad section of your local newspaper where you will find many splendid examples of outcross breeding.
Although our breeding program remains a “hobby” our commitment to the American Blue Lacy remains strong.  We are looking forward to many more fine litters and many more years of great hunting behind our beloved ABLs.   Which remains the single driving force behind our breeding programs.   Good Hunting.

Breeding true to type – Breeding true to the breed

One Response to “Breeding true to type – Breeding true to the breed”

  1. 1
    Lan:

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