highly significantP = 2.19 × 10 −13
In the most comprehensive globally representative sample of Thoroughbreds to-date ( n = 10,118), including prominent stallions ( n = 305) from the major bloodstock regions of the world, we show using pan-genomic SNP genotypes that there has been a highly significant decline in global genetic diversity during the last five decades ( F IS R 2 = 0.942, P = 2.19 × 10 −13 ; F ROH R 2 = 0.88, P = 1.81 × 10 −10 ) that has likely been influenced by the use of popular sire lines.