|You've probably seen the advertisements that tout "41% Poco
Bueno" or "25% Leo." Have you ever wondered how they came up with those
figures? It's not difficult to do.
Percentage of blood simply adds up the approximate
amount a particular ancestor might have contributed to your horse's genetic make-up. This
is not an exact amount, however, as there are a lot of variables involved in breeding
animals. (Watch for a future article about breeding terms such as homozygous versus
heterozygous and in-breeding, line-breeding, and out-crossing.)
The pedigree below is for Alisa Lark, dam of Two-Time
Superhorse, Rugged Lark. She is line-bred on three famous horses
- Joe Reed, King, and Joe Hancock.
||Joe Reed II
|Tommy King mare
|mare by Harmon Baker Jr
||Golden Bear (TB)
|Aliso Gill 3
||Joe Hancock Jr
|Brown Hancock mare
|Sun Queen (TB)
||*Light Brigade (TB)
|Miss Tommy 99
|Riding type mare
Each parent contributing 50% of the genes that make up his or her
offspring. For example, in the pedigree above Alisa Lark received 50% of her genes from
her sire, Leolark, and 50% of her genes from her mother Aliso Gill 3. In turn, Leolark
received 50% of his genes from his father, Lemac, and 50% of his genes from his mother,
Tallalah. Continuing in this vein, Leolark received 25% of his genes from his paternal
grandfather, Leo (Leo gave 50% of his genes to Lemac who in turn gave 50% of his
genes to Leolark). Therefore Alisa Lark would have received 12.5% of her genes from Leo -
50% from Leolark, of which only 50% was from Lemac (25%), of which only 50% was from Leo
(12.5%). However because of the way genes combine, this is only an approximation.
The chart below summarizes the percentages received from each ancestor in a given
generation. Therefore, Leo, a great-grandparent, would have contributed 12.5% to Alisa
Lark. For animals that show up more than once in a pedigree, you only need to add the
percentages together. For example, Joe Reed shows up twice as a GGG-grandparent, therefore
he supplied 3.125 plus 3.125%, or 6.25%. It's the same if the ancestor shows up in
different generations. For example, King shows up as a GG-grandparent and as a
GGG-grandparent, therefore he supplied 6.25 plus 3.125%, or 9.375%.
To help you figure the percentage of blood of a particular ancestor in
your horse's pedigree use the chart and the steps below. Just remember that the percentage
of blood is only an approximation of the inheritance a particular ancestor gave to your
Step 1 - Determine the relationship between your horse and the targeted ancestor.
Step 2 - Find that relationship on the chart to determine the approximate percentage of
blood that ancestor contributed to your horse.
Step 3 - If, as in many pedigrees, the targeted ancestor appears more than once in your
horse's pedigree, repeat steps 1 and 2 for each occurrence and add the amounts together.
Another way to show where and how often an ancestor appears in your horse's pedigree is
by listing the generation for each appearance. For example, in the pedigree listed above
Joe Reed appears twice in the 5th generation. This would be written as 5 x 5. King appears
once in the fourth generation and once in the fifth generation. This would be written as 4
x 5. If an ancestor appears more than twice, just list a generation number for each time
that he appears. Larry Thornton calls this a "linebreeding pattern."
Percentage of blood can be used to help determine when two horses would be a good
cross, but it is only one tool out of many. Beware of the breeder who uses it as the only
tool. Just because two horses have a high percentage of a valuable ancestor doesn't mean
they should be bred together, particularly if they have common faults.