To visualize some of these concepts, please refer to the above pedigree. Linebred ancestors in this pedigree are in color, to help visualize their contribution. The paternal grandsire, CH Loch Adair Foxfire, and the maternal granddam, CH Loch Adair Firefly WD, are full siblings, making this a first-cousin mating. The inbreeding coefficient for a first cousin mating is 6.25%, which is considered a mild level of inbreeding. Lists of inbreeding coefficients based on different types of matings are shown in the table below.

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In Bilye's pedigree, an inbreeding coefficient based on four generations computes to 7.81%. This is not significantly different from the estimate based on the first-cousin mating alone. Inbreeding coefficients based on increasing numbers of generations are as follows: five generations, 13.34%; six generations, 18.19%; seven generations, 22.78%; eight generations, 24.01%; ten generations, 28.63%; and twelve generations, 30.81%. The inbreeding coefficient of 30.81 percent is more than what you would find in a parent-to-offspring mating (25%). As you can see, the background inbreeding has far more influence on the total inbreeding coefficient than the first-cousin mating, which only appears to be its strongest influence.

Knowledge of the degree of inbreeding in a pedigree does not necessarily help you unless you know whose genes are being concentrated. The percent blood coefficient measures the relatedness between an ancestor and the individual represented by the pedigree. It estimates the probable percentage of genes passed down from a common ancestor. We know that a parent passes on an average of 50% of its genes, while a grandparent passes on 25%, a great-grandparent 12.5%, and so on. For every time the ancestor appears in the pedigree, its percentage of passed-on genes can be added up and its "percentage of blood" estimated.

In many breeds, an influential individual may not appear until later generations, but then will appear so many times that it necessarily contributes a large proportion of genes to the pedigree. This can occur in breeds, due to either prolific ancestors (usually stud dogs), or with a small population of dogs originating the breed. Based on a twenty-five generation pedigree of Bilye, there are only 852 unique ancestors who appear a total of over twenty-million times.

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Pedigree Analysis of Laurel Hill Braxfield Bilye (computed to 25 generations)

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The above analysis shows the ancestral contribution of the linebred ancestors in Bilye's pedigree. Those dogs in color were present in the five-generation pedigree. CH Afternod Drambuie has the highest genetic contribution of all of the linebred ancestors. He appears 33 times between the sixth and eighth generations. One appearance in the sixth generation contributes 1.56% of the genes to the pedigree. His total contribution is 33.2% of Bilye's genes, second only to the parents. Therefore, in this pedigree, the most influential ancestor doesn't even appear in the five-generation pedigree. His dam, CH Afternod Sue, appears 61 times between the seventh and tenth generations, and contributes more genes to the pedigree than a grandparent.

Foundation dogs that formed the Gordon Setter breed also play a great role in the genetic makeup of today's dogs. Heather Grouse appears over one million times between the sixteenth and twenty-fifth generations, and almost doubles those appearances beyond the twenty-fifth generation. He contributes over ten percent of the genes to Bilye's pedigree. This example shows that the depth of the pedigree is very important in estimating the genetic makeup of an individual. Any detrimental recessive genes carried by Heather Grouse or other founding dogs, would be expected to be widespread in the breed.

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Breeding by Appearance

Many breeders plan matings solely on the appearance of a dog and not on its pedigree or the relatedness of the prospective parents. This is called assortative mating. Breeders use positive assortative matings (like-to-like) to solidify traits, and negative assortative matings (like-to-unlike) when they wish to correct traits or bring in traits their breeding stock may lack.

Some individuals may share desirable characteristics, but they inherit them differently. This is especially true of polygenic traits, such as ear set, bite, or length of forearm. Breeding two phenotypically similar but genotypically unrelated dogs together would not necessarily reproduce these traits. Conversely, each individual with the same pedigree will not necessarily look or breed alike.

Breedings should not be planned solely on the basis of the pedigree or appearance alone. Matings should be based on a combination of appearance and ancestry. If you are trying to solidify a certain trait - like topline - and it is one you can observe in the parents and the linebred ancestors of two related dogs, then you can be more confident that you will attain your goal.

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Go to PART III