The linebreeding report in AllBreedPedigree.com is a great tool for my studies of the
Connemara pony stallion population and for helping other breeders understand how to
manage inbreeding in their ponies. The Connemara breed derived from local ponies of
mixed ancestry with known additions of Thoroughbred, Arabian and Irish Draft. However, like
most recorded breeds the Connemara pony began with a very small select group of stallions
in the 1920’s with one line quickly dominating and that line dominates today.
The Connemara pony studbook was closed in 1964 and like all closed studbooks needs to
monitor and manage inbreeding and genetic diversity. I have been using
allbreedpedigree.com for many years as an essential tool for assisting breeders who do not
have any formal genetics training. The linebreeding report is valuable for stallion population
studies and for hypothetical matings.
The Linebreeding report analyses 9 generations for ancestors that appear two or more
times, as a default maximum. Using the default 9 generations provides the most
comprehensive report available from allbreedpedigree.com.
The two numbers that are most useful to me are Blood % and AGR % (Aggregated Genetic
Relationship), as they summarise the Crosses and Lines information. Influence is an
abbreviated and rounded summary of Blood %.
Blood % is a simple addition of the % of a pedigree that an individual ancestor contributes
regardless of the breed that it is recorded as. A parent is generation 1 contributing 50%,
generation 2 is a grandparent contribution 25%, generation 3 is a great grandparent 12.5%,
and so on. The percentage contributed halves each generation.
For example, in the pedigree of Carna Bobby https://beta.allbreedpedigree.com/carna-
bobby-iTatlPfF/pedigree. In his pedigree his grandsire, the Connemara pony stallion Rebel,
born in 1922, derives from Welsh Cob type ponies and other undescribed ponies and
horses. Rebel appears two times in generation 3, contributing 12.5% of generation 3 x 2 =
25% which matches the linebreeding report blood % for Rebel.
Blood % is a useful simple to understand concept and is the default sort for the linebreeding
report. However, it does not consider genetic relationships between related individuals that
are repeated in an individual’s pedigree.
AGR% is the Aggregated Genetic Relationship within the pedigree of the individual and each
repeated ancestor. It takes account of the genetic relationship of various individuals in a
pedigree when assessing their contribution to the pedigree. Where an ancestor, usually a
sire, is seen repeatedly in a pedigree the AGR % gives a better analysis of the individual
ancestor’s genetic contribution to the pedigree that is being reviewed.
Courtesy of:
Fiona Comer
B. Ag. Sci (Massey, NZ)