Pedigree analysis of the racing line Quarter Horse: Genetic diversity and most influential ancestors

The aims of this study were to evaluate the genetic diversity racing line Quarter Horse breed in Brazil and provide data on most influential ancestors by pedigree analysis. All horses that had participated sprint races between 1978 2016 evaluated. There 5,861 athletes (2,474 males 3,387 females) born 1971 2014. These animals referred as population (Pr), which was divided into three subpopulations complete decades (84.5% Pr). consisted 1,712, 1,604 1,461 1980s (sP80), 1990s (sP90) 2000s (sP00), respectively. quality assessed based number equivalent generation traced. 5.4 4.7 5.7 6.3 (sP00) generations, permitted accuracy conclusions reported. intervals long, with 13.2 (sire-son/daughter) 10.6 (dams-son/daughter) years (Pr). coefficients inbreeding average relatedness 0.95% 1.84% for Pr 1.60% 2.56% sP00, In effective size (Ne) ΔFi 215 144, respectively, 68 41 per generation. probability gene origin given founders (fe), (fa) founder genome equivalents (fge) 192, 61 34, Pr, considerable losses over last (founders or not) explained total 1,587. This is considered high; however, only 32 9 50% 10 sP00 52.2% diversity. loss concentration a reduced breeding indicate failures conservation programs line. Mating designs conjunction selection should be promoted goals defined Brazil.