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Figuring Ancestry Percentages

"Figuring percentages of ancestry is ...a numerical way of describing what your bloodlines represent"

condensed from the original article

Recently I learned of a valuable tool for the Aussie breeder; bloodline percentages. Figuring percentage of ancestry is not all that hard, and I would like to help you learn how quick and easy it can be to understand. It is a numerical way of describing what your bloodlines represent. It can be a good sales tool, but most importantly, it can help guide you towards a goal in your breeding program.

A percentage can only be based on one individual ancestor at a time. Livestock producers have been using percentages for years now. The basic principle has been applied to agriculture since the monk Gregor Mendel first experimented with his peas over a hundred years ago. The percentage based on an individual measures approximately the chances of his genes appearing in the current individual. Percentages can be used to move away from degree of inbreeding as well as towards a level of line or inbreeding to fix a certain type. In breeds where the number of foundation individuals is very small, breeders may want to diversify their gene pool and thus work at lowering certain individual percentages. It is well known that genetic diversity is a strength in an individual regarding health and fitness.

Thus, when using percentages it is important to keep the individual well in mind and first consider the breeding stock itself before worrying about the appeal of the pedigree.

There are at least three ways to approach figuring percentages of ancestry. I like to work from the back, forward. Bust first, let's read a pedigree left to right. (See figure 1) (double left click on the chart & it will enlarge)

percentages.JPG (59224 bytes)

As I figure X's percentage of A, I go to the second generation , add up 50% of A's son on the top side and add 100% for A himself on the bottom side. I then divide by four because there are four individuals in the second generation. X = 37.5%.

If you want to figure out the percentage from the front going backwards (left to right), simple reverse your outlook. X = 100% so looking back, on top A is 12.5% and on the bottom, A is 25%. From here we just add these together and get 37.5%.

With figuring the percentage of an early foundation dog, I believe it is easiest to work from the back forwards. In extended pedigrees this has to be done in steps. Pedigrees must be extensively researched to provide accuracy. For instance, you Aussie may have ten generations of recorded ancestry. You have to get the percentages figured out for all 32 individuals represented in the fifth generation, add these up and divide by 32 to get the percentage for the target individual. 

You may be able to utilize the computerized Compuped program instead of doing all this by hand as I have learned to do. But please realize that you still have to know whether the computer has full and accurate data to work with. It is also noted that figures under 10% are not considered to contribute to any great extent to individual qualities. But in figuring a complete pedigree, I feel any small percentage should still be included to maintain accuracy. An individual's great-great grandparent has the chance to affect the present with a contribution of only 6.25%; this is in the fourth generation in a pedigree. If you looking at a pedigree with your desired blood relative only once in the firth generation, his contribution will be virtually nothing at 3.125%. However, the percentage adds up quickly when the foundation individual is permeated throughout the pedigree. 

Again, it cannot be stressed enough that first you look at the individual. Is it bringing the genetic qualities to you program that you are interested in? If it is, percentages now become a very important tool for future planning. 

Remember that pedigrees from registries may not be complete due to transfers in breeder use between several sources. Thus we rely on foundation breeder records and written histories shared through the years. However, the idea of using percentages need not be daunting; have fun!

Here are some examples found in my research of the percentage of Wood's Jay (1949-1964) in some Aussies from the 1970's (Sisler's Shorty lived 1948-1959). Those highlighted are in the various photo albums that can be seen on this site.

And on into the 1980's:

And in the 1990's:

But look at the percentage of Wood's Jay in some "show bred" Aussies!:

A person could say that the strength of the Flintridge line was built on the daughters and grand-daughters of Wood's Jay: Smedra's Blue Mistingo (who was prick-eared, by the way) Lighter's Asta, Nettesheim's Twinkle and Nightingale's (Sorensen's) Tammy.

Pedigree search sources for the Australian Shepherds include: The Aussie Heritage by Carol Troop (phone404-475-3690), 1501 Mid Broadwell Rd, Alpharetta, GA 30201; as well as Kris Toft's series of Australian Shepherd Pedigrees. Volumes I and II are especially valuable as these include most to the foundation dogs. They are very easy to use.  And let's no t forget ASCA's treasures in the form of its tow yearbooks. Pedigrees from registries may not be complete due to transfer in breeder use between several sources. 

The idea of using percentages need not be daunting; have fun!

Offspring of Wood's Jay found in the  Herdn Dog Database and Paw Village Database. The links will take you to the respective pedigrees

Aringtons Stub Holland's Nikki  Sislers Panda Woods Shep
Cannons Snoopy Lighter's Asta Sorensens Amy Woods Slate
Dingo Too Nettesheim's Twinkle   Woods Specks
Gabriels Woody   Wood's Chili   Woods Specs
Green's (Shannon's) Dingo  Piz Joseph  Wood's Pepsi Cola  or Healys Pepsi Cola Woods Strip
Greens Kim Piz Lady I Woods Stubby

 

Copyright 1982 [CHEVREHERD Australian Shepherds]. All rights reserved. Page last edited: 07/16/03