EN
Tested were 1788 purebred Arabian fillies and colts raced during the following periods: I (seasons 1927-1939), II (seasons 1946-1961) and III (seasons 1962-1992). There were divided into groups according to quantities of horses submitted to performance trials (more than 20 heads, 5-20 and less than 5 ones). It was found, that in greater herds more often occurred extreme values of coefficients of success per head. The highest value was observed in the I period and resulted 1.73.