RT Journal Article SR Electronic A1 Stachurska, Anna A1 Brodacki, Antoni A1 Liss, Marta T1 Allele frequencies in loci controlling coat colour in Polish Coldblood horses JF Czech Journal of Animal Science YR 2018 VO 63 IS 11 SP 462 OP 472 DO 10.17221/107/2018-CJAS UL https://cjas.agriculturejournals.cz/artkey/cjs-201811-0005.php AB The objective of this study was to estimate the frequencies of alleles which produce coat colour in Polish Coldblood horse population, and to verify the hypothesis that coat colour is not considered in its selection. The analysis included 35 928 horses and their parents having been registered in the studbook over a half-century. Allele frequencies in Agouti (A), Extension (E), Dun (D), Roan (Rn), and Grey (G) loci, in parental and offspring generations, were estimated according to test matings and the square root of recessive phenotype frequency. The population structure is in Hardy-Weinberg equilibrium only at E locus and coat colour is regarded by breeders. Black horses are favoured. Higher E locus homozygosity in blacks than in bays makes it easier to obtain black foals. Dun-diluted, roan and grey coat colours are undesirable and the population has come to consist almost uniformly of basic coat colours. These results show the importance of studies on population genetic structure, which despite no formal criteria for breeding for colour, can considerably change through generations.