We have added Contribution of Blood as a value in the ancestor-listings of IWDB. Interpreting these data is something some people are very used to, while it’s unknown territory for others.
Contribution of blood is an estimation of the genetic contribution made to an individual by a specific ancestor. It is given as a percentage. The base theory is that each of the parents contribute half of the genetic makeup for the offspring (50%). Each grandparent contribute a quarter (25%) each, and so on.
For each generation, the total contribution totals 100%. For each generation we go back, any single ancestor’s genetic contribution thus gets less important. A dog 10 generations back contributes less than a tenth of 1% of its genetic material to the present generation.
The contribution of blood should not be interpreted as giving a precisely accurate measure of the genetic contribution in a hound. In these calculations, the whole of generation 10 seems to be as influential as the parents. That’s not how these things work.
Look at the contribution table below, there is a cumulative effect of each generation. Each parents 50% contribution is made up of 25% from each grandparent, which is made up of 12.5% from each great-grandparent, and so on back through the generations.
|Generation||Contribution pr appearance|
How can I use this?
These values are useful to see which dog is more influential in a certain breeding-program. This is especially true if the breeder is linebreeding. Then one of the more interesting questions is “who are you linebreeding on?”. The contribution of blood will give a good answer to this question. Look for the hounds with high percentage in common ancestors.
If a dog’s parent is also a grandparent on the other side of the pedigree then we can see that this ancestor has contributed 75% of the genetic make up of the dog. It’s not so easy to calculate when an individual appears twice in the 4th generation, 3 times in the fifth generation and once in the 6th generation. Or if she appears 12 times in the 8th generation, 8 times in the 9th and 7 times in the tenth. It’s a very handy way to see genetic influence without having to calculate all of this yourself. When we get way back in the pedigree, it’s quite common that certain dogs appear many times in many generations, making it hard to calculate. Now IWDB can tell you how much genetic influence that ancestor has on your own dog.