Genetic parameters of racing performance indices in Polish Arabian horses

The aim of this study was to estimate the genetic parameters for racing performance of purebred Arabian horses in Poland. The traits used were coefficients of success (CS) and of running intensity (CI). The data included annually summarized race records of three- and four-year old Arabian horses being performance tested at the Polish racing tracks during the years 1946–1992. Coefficients for three- (CS3, CI3) and four-year olds (CS4, CI4) were analysed separately. The racing results were available for 2590 horses descending from 172 sires and 736 dams. Variance components estimation using REML method and VCE software gave the following values for heritability: 0.07, 0.09, 0.41, 0.18 for CI3, CI4, CS3 and CS4, respectively. The highest genetic correlations were obtained between CS3 and CS4 (0.9) as well as between CI3 and CI4 (0.7). There were no genetic relationships between CS3 and CI4 (rg =−0.06). Genetic correlation between CS3 and CI3 was 0.45 and between CI3 and CS4 was 0.19. The opposite signs of genetic and phenotypic correlations (− 0.42 vs 0.44, respectively) between earnings and starting frequency for four-year-olds were observed. The correlations of observed breeding values of sires and dams (expressed as averages of the adequate coefficients achieved by a horse's progeny as three- or four-year-olds) and estimated breeding values (BLUP-EBV's) for CI and CS varied from 0.34 to 0.82. These correlations tended to decrease with decreasing estimates of heritability. The restriction of ten or five progeny in sire and dam analysis, respectively, increases the correlations, with the exception of CI4 for sires.