AVERAGE COEFFICIENT OF INBREEDING

AN ATTEMPT TO COMPUTE AN AVERAGE SIC AND AN AVERAGE CIC FOR THE THOROUGHBRED

All calculations were made using Hardiman's Method - See COEFFICIENT OF INBREEDING

STANDARD INBREEDING COEFFICIENT (SIC) - includes only the subject's inbreeding in the first five generations
CUMULATIVE INBREEDING COEFFICIENT (CIC) - includes all inbreeding in the subject's pedigree back as far as records allow

See REGISTER OF INBREEDING COEFFICIENTS

All SIC and CIC values are shown to two decimal places

NUM - Unique number given to each ancestor to aid identification. This is not a registration number

An understanding of the identities and breeding of the earliest ancestors of the thoroughbred is essential for the creation of an average coefficient of inbreeding. The naming of horses in the seventeenth and eighteenth centuries was very casual. It was not uncommon for a horse to race under three different names for the same owner in the same year. Some would race in the same name for different owners and in different names for different owners. Some raced unnamed under their owner's name or in the name of their sire or dam. Some raced in one name and covered in another. Some were known by different names in different parts of the country. Some stallions with names were also known as unnamed Arabians, Barbs or Turks, under the names of their owners, even if they were foaled in England. Some of these had many owners and were consequently known by many names. The lack of any central registration system meant that each new owner had to take the pedigree he was given at face value and the majority of these were correct, but there is no doubt that some fictions were introduced in order to dupe prospective buyers. Errors and omissions in some of the pedigrees were accepted by new owners as correct and handed forward, while some pedigrees were written down in such a manner that they were difficult to understand.

In all the pedigree databases I have encountered, many ancestors have been entered as they appear in each pedigree, even though it is known that some with different names refer to the same horse. There are, therefore, many pedigrees where the duplication of an ancestor has gone unnoticed and has not been reflected in the inbreeding summary.

Using new evidence, new interpretations and conjecture, I have endeavoured to assign one name to each horse. I have also merged many of the old unnamed mares and traced them back to the original foundation mares. Each horse in the register has been given a number to aid identification. If a horse appears in the register under more than one name then each appearance will have the same number followed by a letter.

Galileo, the greatest stallion that has ever lived, traces back in the male line to Darley's Arabian. He is by Sadler's Wells by Northern Dancer by Nearctic by Nearco by Pharos by Phalaris by Cyllene by Bona Vista by Bend Or by Doncaster by Stockwell by The Baron by Birdcatcher by Sir Hercules by Whalebone by Waxy by Potoooooooo by Eclipse by Marske by Squirt by Bleeding Childers by Darley's Arabian.

This is the backbone of the breed and about 95% of all thoroughbreds trace back to this male line. I doubt if there is a thoroughbred alive today that does not have a cross of Nearco. My aim therefore is to compile the complete pedigree of Galileo, calculate the coefficients of inbreeding for each ancestor and produce an average which can be used to represent the breed.

The Baron is the first stallion in the line to have a cross of the cart horse and a pedigree that contains nearly all the foundation stock.

I have calculated the coefficients of inbreeding for The Baron and his 591 ancestors and the results are shown below.

THE STANDARD INBREEDING COEFFICIENTS FOR THE BARON AND HIS ANCESTORS

THE CUMULATIVE INBREEDING COEFFICIENTS FOR THE BARON AND HIS ANCESTORS