Genomic Structure of Native Iranian Arabian Horses

The Arabian horse originated in the Middle East, where it remains prized for its beauty, endurance, and intelligence. Arabians have been exported to many countries of the world, where they are used in long distance and flat racing events, and in show competitions. Outside the Middle East, notable populations of Arabians have been bred in Russia, Poland, England, the USA, and Brazil, and international movement of horses and shipping of semen has created a cosmopolitan pedigree. In contrast, there has been relatively little exchange of Arabian horses between Iran and the rest of the world for several decades. Since 1952 the Iranian Equestrian Federation has maintained a studbook for native, or Asil (purebred), Arabians. Here we analyzed pedigrees of 4384 Asil horses born between 1952 and 2015. The population has an estimated 707 founders, an average inbreeding level of 4.67%, and an effective population size of 183 based on increase in inbreeding by maximum generation. We selected 75 horses from this population for genomic analysis using the Equine 670k Affymetrix SNP chip. The horses were chosen to minimize relatedness to one another and to be representative of the Iranian Asil Arabian population. This study is designed to characterize the genetic makeup of the Iranian Asil Arabians, and also to determine the relationship between the Iranian Asil horses and Arabian horses with international pedigrees.