Breed demarcation and potential for breed allocation of horses assessed by microsatellite markers.

The study investigates the clear demarcation and potential for breed allocation of horses using data from different breeds and applying both phylogenetic analysis and maximum likelihood methods. Over 99% of the studed horses were successfully allocated to their respective breeds.

Research Methodology

• The study involved the population demarcation of eight diverse horse breeds using genetic information from 26 microsatellite loci across 306 horses.
• The breeds included both indigenous Norwegian breeds like the Fjord Horse, Nordland/Lyngen Horse, Døle Horse, and Coldblooded Trotter, among others, as well as internationally known breeds such as the Icelandic Horse, Shetland Pony, Standardbred and Thoroughbred.
• The research used a phylogenetic analysis and a maximum likelihood method to investigate the potential for breed allocation of individual animals.

Phylogenetic Analysis

• The phylogenetic analysis applied in the study was based on simple allele sharing statistics.
• This uncovered clear demarcation among the horse breeds. Exceptionally, 95% of the horses investigated clustered together with other animals of the same breed in the phylogenetic tree.
• Even horse breeds with a short history of divergence, like the Døle Horse and the Coldblooded Trotter, formed distinct clusters in this analysis.

Maximum Likelihood Method

• The maximum likelihood method was also applied in the study, which managed to allocate 96% of the horses to their source population.
• This was successful when applying an assignment stringency of a log of the odds ratio greater than 2.
• When the assignment stringency is reduced, nearly all the horses could be allocated to their respective groups.

Conclusion and Results

• The results of the study showed a clear distinction among horse breeds when both the phylogenetic analysis and the maximum likelihood method were utilized.
• Just three horses were misallocated a breed by both methods.
• In conclusion, the research demonstrated that it’s possible to determine breed allocation for more than 99% of the individuals with a combination of these two methods.