Performance in racehorses of various colours

A relationship between the coat colour and the horse's performance, which has been suggested since centuries, is possible from the genetic point of view. It may result from a linkage of genes affecting these characters and from pleiotropy of certain genes. The objective of the study has been to examine if there is a relationship between the basic and grey colours and the racing results. Indices (number of starts, log of earnings, log of earnings per start, general handicap) of 14,504 starts from 1103 Thoroughbreds and 796 Purebred Arabians were analyzed. In the analysis of variance, the phenotypes have been considered according to the brightness of the colour (grey/chestnut/light bay and bay/dark bay/seal brown/black), with regard to the alleles in G locus (grey/non-grey) and the alleles in MC1R locus (phaeomelanic/eumelanic). The results indicate that the examined coat colours are not considerably related to the racing performance. A tendency of such relationship may be due to the physiological properties connected with the brightness of the hair and the activity of alleles from MC1R (Extension) locus. No difference found between the results of grey and non-grey horses indicates that possible QTLs affecting the racing performance are not linked with the Grey locus.