Genomic characterisation of Irish DroimFhionn cattle
Fergus Ó Súilleabháin1, Paul Flynn2, & Donagh Berry3
1
DroimFhionn Breed Society
2
Weatherby’s Ireland
3
Teagasc, Moorepark
The DriomFhionn (Droimeann) cattle breed have been part of the Irish (& probably
Celtic & European) landscape for a long time. With only an estimated 200 pure or
near pure breeding females remaining the objectives of this study were to 1)
genomically characterise each animal, and 2) quantify the genomic relationships
among candidate breeding males and females to minimise the accumulation of
inbreeding.
Single nucleotide polymorphism data (6651 SNPs) from 188 DroimFhionn cattle were
collected from 14 different herds. The genomic information showed that although a
considerable proportion of the DroimFhionn animals were close to purebred, several
animals had a notable proportion of, in particular, Angus and Holstein-Friesian
bloodlines most likely due to a recent ancestor. The proportion of DroimFhionn per
animal varied from 15% to 100% with an average of 69%.
Recorded pedigree errors in the herdbook were corrected using the genomic
information available. Mean genomic inbreeding of the population was 2%. The
average genomic coancestry between the genotyped males and females was 4.7%
(compared to 1.87% when estimated using pedigree only). Maximum coancestry per
bull varied from 14.2% to 32.3%. Several candidate bulls with a high proportion of
DroimFhionn blood lines but also least related to the breeding female population were
identified.
The DGAT1 polymorphism was almost fixed in DroimmFhionn. The frequency of the
A2 betacasein polymorphism in the DroimFhionn was 47.5% which is lower than the
80% in the 10 Kerry cattle also genotyped yet similar to the 55% prevalence estimated
in 100 Holstein-Friesian bulls with genotypes also included in this study. Although no
Brachyspina, CMD2, CVM, Ferrochelatase, or Hyoimmpotrichosis -KRT71 was
present in the DroimFhionn there appears to be one carrier animal for Tibial
Hemimelia.
The recommendation is that remaining DroimFhionn cattle should be genotyped and
all newborn DroimmFhionn cattle should be genotyped routinely to monitor progress
in attaining greater breed purity but also monitoring of coancestry and thus future
inbreeding. The mating plan for the coming season should be based on male
performance, adherence to breed characteristics, genomic breed purity and coancestry
with the female population. Potential bull dams of subsequent generations should also
be detected and optimised contribution theory imposed to ensure long-term genetic
gain. Semen should be, where possible, ejaculated from bulls and stored to ensure the
long term survival of the breed.
Project Coordinator: Louis Barton