By Horse Sport Ireland / HSI
Graphics: Horse Sport Ireland
The traditional method of parentage verification of Irish Sport Horse (ISH) foals utilised genetic markers known as microsatellites (MS). The technology used in MS testing was developed in the 1970s.
In Ireland, the system proved difficult to maintain during the COVID pandemic where animal laboratories were not seen as high priority; this led to a backlog in parentage testing of ISH foals and to some ISH hair samples being sent as far as California for testing.
In contrast, the beef and dairy industries in Ireland had no such issues as they have utilized the more modern Single Nucleotide Polymorphism (SNP; pronounced ‘snip’) genetic markers for parentage testing since 2009. Aside from reducing the use of the dated MS technology, there are many other benefits to utilizing SNPs over MS, including health testing, monitoring major/lethal genes, monitoring inbreeding, improving traceability, testing breed composition, and many more. Because of this, Horse Sport Ireland (HSI) made the decision to propose a transition scheme under funding provided by the Department of Agriculture, Food and the Marine (DAFM). The transition fund was approved by DAFM for use by sport horse studbooks in Ireland. Hence the Irish Sport Horse studbook began the process of transitioning parentage verification to SNPs in 2022.
Starting the transition
The initial transition began with genotyping a reference library of influential stallions and mares that were identified as having a significant genetic impact on the ISH population. Building this reference library was made viable to all Irish passport issuing organizations (PIOs) and studbooks through funding from the Irish Department of Agriculture, Food and the Marine (DAFM) via the HSI-administered National Breeding Services.
All PIOs had their own method of choosing relevant horses to genotype; the ISH horses genotyped as part of the reference library were either actively breeding already, or were younger high genetic merit horses that were thought to begin breeding soon. It was also made a prerequisite of ISH studbook inspections that all stallions and mares presenting at an inspection have a hair sample taken for genotyping. During this first transitional year, parentage verification of foals continued using MS only, and approximately 8,000 horses were SNP genotyped from all Irish PIOs, with just over 2,500 relating to the ISH studbook...
