Part I: History of Breeding Strategies
by Melissa E. Parsley, Parsley Glen
|Whenever two breeders get together they
are almost certain to speak of pedigrees. Yet
surprisingly few will have a clear idea of what is meant
by the pedigree and what alternative breeding methods
This article will endeavor to tell in simple terms what is meant by "inbreeding," "outcrossing" and "linebreeding," and to show how these methods can be used in your pedigree to map out a breeding program that can improve your stock. With care, your pedigrees can become a map to guide you where you want to go, to get the look you wish to see consistently produced and the soundness upon which to base your line.
For centuries the animal breeder depended upon the method of survival of the fittest to guide his breeding plan. Few had the knowledge and wisdom to handpick the best breeding pairs for improvement of their herds. A notable exception was the biblical herdsman Jacob, who was born in 1858 B.C. In a dream he was taught that certain principles of genetics, and not superstitions, were responsible for the amazing success in his breeding program. Apparently the solid-colored sires were producing spotted offspring due to hereditary factors carried in their genes for generations (and according to the laws of genetics later discovered in scientific study by the monk Gregor Mendel). The solid-colored sires were hybrids, built up from generations of crossbreeding between spotted and plain-colored ancestors. God explained to Jacob that, hidden beneath the plain-colored coats, certain of the males were actually spotted sires. Jacob made a fortune with this gem of genetic insight.
In the 1900s science began to assist animal breeders. Mendel (1822-1884) had defined certain rules of genetics (and anyone today can find the outcome of his studies in any eighth-grade science book in plain and simple terms). However, it was the animal breeder Robert Bakewell who would put these laws to work on domestic animals and claim for himself a well-deserved fame as not only the foremost breeder of the world, but also as the "Father of Pure Breeding." Born in Leicestershire, England, he earned this title by transforming the important classes of domestic animals into the producers we know and trust today. He used the method of "close breeding," i.e., the breeding in family lines. All modern breeding theories are based upon Bakewells work.
The two basic laws he discovered are: (1) "Like produces like," and (2) "No two animals are ever identically alike." Because of the first law, a breeder can stick to a family line of dogs, breed from fairly close relationships of animals possessing the required qualities and quickly build a strong line. This method is called linebreeding. The best choices of top-producing lines in the Shetland Sheepdog breed can be found already researched for you in the diagram in the book Sheltie Talk (page 4). Linebreeding is considered to be both fast and effective, but it holds certain dangers for the unwary.
Because of the second law, we notice a variation in our animals. Therefore, a process of selection is necessary (and thats where your responsibility as a breeder comes in), but it is also effective. In other words: Human choice is responsible for both improvements and the variations in type that we see in our breed. Many breeders use the method of "outcrossing" in which they choose the best to breed to the best, regardless of relationship. This is a safe method but slow.
The third method is that of crossbreeding. The variety in type derived from this method will be difficult to standardize into its own breed. First-crosses only work where the qualities most desired are dominant or where the two breeds originated from a common source. Such breeding should be undertaken only by the breeder who will devote his full lifetime to the project, who has a good working knowledge of Mendels laws on genetics, and who can keep firmly in mind his own ideal and continuously tighten his program along such an ideal. ("Dogdom" is filled with good examplesone that comes to mind is the Jack Russell terrier.)
Inbreeding was the basis of Blakewells success. It consisted of the mating of mother to son, sire to daughter, or brother to sister. Inbreeding will not of itself create superior specimens from inferior stock, for the proper factors must be present in the first place and the best quality must be the basis for your work. But, because bad qualities are inbred with the good, it takes vigorous selection on the part of the breeder to eliminate the bad characteristics by rejecting them. Inbreeding, when based on a prime foundation and practiced through vigorous selection, is one of the most reliable means of purifying a breed. Best of all, the resulting offspring will have, through process of elimination, a prepotency backed by the most powerful of hereditary influencesobtained because of the simplicity and strength of the ancestry. However, unless the breeder recognizes a good dog from the particular breed when he sees one and possesses the right stock to start with, inbreeding can bring disaster as the breeder tightens in bad points. Most purebred animals have a written Standard, which should act as the bible for a breeding program, dictating what is acceptable and what is not. Every breeder should have studied the Standard until the word-picture forms a vivid vision in his minda vision beside which he stands each animal he produces in his program. Today we have the added benefit of the Illustrated Standard by Jean Simmonds and articles in our breed magazines to help us develop our eye. However, it takes more than just reading the Standard now and againit takes a concerted effort and a true study.
Another point to consider is the necessity of selecting your stock for more than their show potential. Unfortunately, many of our champions are not suitable breeding dogs as it is equally important that their potency and potential for reproduction be carefully guarded. Also, domestic animals must be easy to handle and possess a manageable temperament. When you select for vigor and fertility, as well as temperament and the sound structure called for in your breed, the future of your lines will be guaranteed.
The difference between linebreeding and crossbreeding is in the degree. Whereas inbreeding mates father to daughter, and mother to son, and brother to sister, linebreeding begins with mating half-brother to half-sister followed by mating of uncles to the resulting offspring (or aunts or cousins of all kinds in a close selection of lines). The development of a pure line will eventually occur. The line should be superior to the average in the breed. A linebred pedigree is valuable or dangerous in exact proportion to the quality of the individual dogs from which you have selected. Linebreeding will give you a wider range of choice within your breed.
So, to review, both good and bad hereditary characteristics are present in various degrees in every animal. For improvement, we wish to secure and retain the desirable characteristics. This can be best accomplished through inbreeding and, to a lesser degree, by linebreeding. Using these methods, undesirable traits can be bred out and desirable traits can be bred in, while always keeping in mind that your end product can only be as good as the foundation it was built on. As Lloyd Bracket, the father of the German Shepherd breed, put it: "Physical compensation is the foundation rock upon which all enduring worth must be built."
Part II will cover examples from history and inbreeding versus outcrossing. Part III (the concluding article) will explain how to build up your dogs pedigree.
Part I first appeared in the July/August 1994 issue.
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