Here’s a pedigree note about inbreeding that I thought you would find interesting. I’ve been reading “Horse Breeding In Theory And Practice” by Burchard Von Oettingen which was published in 1909 by Sampson Low, Marston & Co.
In his chapter on Inbreeding Oettingen states:
“Common ancestors constitute the basis of inbreeding. By “free generations” is meant the number of generations between the common ancestors and the sire on the one side, and between the common ancestors and the dam on the other side.” - page 224
“…There has been also much damaged by exaggerated inbreeding in the American Thoroughbred breeding. Among the many instances of 0 free generation I have not found a single one in the American Stud Book which has been of importance to breeding. I have only found one good racehorse in the American Breeding, and that is Henry 1819 by Sir Archy-Doimed (i.e. 0 Diomed), celebrated by his famous match with the American Eclipse in New York, 1823.” - page 233
Here’s the pedigree of Henry: http://www.pedigreequery.com/henry
On page 318, Oettingen lists the number of male and female winners of the Derby, St. Leger and Oaks arranged according to free generations of inbreeding. Oettingen concludes:
“1. On the whole the most of the classical winners are found among the 4 free generations, next to which follow the 3 and 5 free generations.
“2. Up to the middle of the past century the 4 free generations predominate also. …
“3. From the middle of the past century up to now the whole picture has been changed in favour of a more removed inbreeding. Here the 5 free generations appear to be the most favourable only, after which follow the more removed inbreedings with 6 free generations, and finally that with 7 free generations.
“4. Lastly, it is worthy of note that the winners of two classical races have been more numerously represented with the more removed inbreedings."
Oettingen then proceeds to illustrate in another table on page 319 the male and female winners of the Derby, St. Leger and Oaks that were born until the year 1895 that were most successful at stud:
“The same change in favour of the more removed inbreeding is shown in the following table, in which the percentage of stallions and mares most successful in breeding is reckoned from the above list. Accordingly, the percentage of stallions most successful in breeding increases with the number of free generations up to 6 free generations [59.1%], in the case of mares even up to 7 free generations [75%].”
I found Oettingen’s analysis interesting in that the farther inbreeding is removed from the foal, the better chance you have a producing a quality thoroughbred.
Although unscientific, I conducted my own survey of modern-day Triple Crown Champions and found similar statistics:
1978 – Affirmed = inbreeding in 4th and 5th remove; 1977 – Seattle Slew = inbreeding in 4th and 5th remove; 1973 – Secretariat = no inbreeding in 5 generations; 1970 – Nijinsky = inbreeding in 5th remove; 1948 – Citation = inbreeding in 4th and 5th remove; 1946 – Assault = inbreeding in 5th remove; 1943 – Count Fleet = inbreeding in 4th remove; 1941 – Whirlaway = inbreeding in 4th and 5th remove; 1937 – War Admiral = no inbreeding in 5 generations; 1935 – Omaha = inbreeding in 4th and 5th remove; 1930 – Gallant Fox = inbreeding in 4th and 5th remove; 1919 – Sir Barton = inbreeding in 3rd , 4th and 5th remove.
Here is also what I found for three of, perhaps, the most important Thoroughbreds of all time: Man o’ War = inbreeding in 5th remove; Secretariat = no inbreeding in 5 generations; Ribot = inbreeding in 5th remove.
Other important Thoroughbreds include: Northern Dancer = inbreeding in 4th and 5th remove; Mr. Prospector = inbreeding in 4th and 5th remove; Nearco = inbreeding in 4th and 5th remove; Native Dancer = inbreeding in 4th and 5th remove.
Here’s some other interesting statistics applicable to more recent times: Zenyatta = inbreeding in 4th and 5th remove; Rachel Alexandra = inbreeding in 4th and 5th remove.