title: Common white facial markings in bay and chestnut Arabian horses and their hybrids.
abstract: Common white facial and leg markings have a multifactorial mode of inheritance in Equus caballus. Evidence for the complexity of the genetic component is the observation that chestnut (e/e) horses have more extensive white markings than do bay (E/-) horses. Computerized records obtained from the Arabian Horse Registry of America, Inc., were used to determine if heterozygous (E/e) bay horses have more extensive white facial markings than do homozygous (E/E) bay horses. Thirty-five sire families were analyzed. Each sire family consists of a sire, his foals, and the dams of those foals. The facial region was divided into five areas, and each horse was given a score from 0 to 5 according to the number of areas with whiteness. Since dams and foals with E/E genotypes cannot be identified in these sire families, mean facial scores were compared in dams and foals that were E/e and E/-. It was assumed that if a difference exists between E/e and E/E horses, the presence of E/E horses in the E/- group would reduce the mean of the E/- group. The results show that Arabian horses with the genotype E/e have more white markings than do horses with the genotype E/-, leading to the conclusion that horses with the genotypes e/e, E/e, and E/E vary as to the quantitative expression of white facial markings, with heterozygotes having an intermediate expression.
authors.affiliation: Department of Zoology, Arizona State University, Tempe 85287-1501.
authors.forename: C M
authors.initials: CM
authors.lastname: Woolf
mesh_terms: D000818:Animals; D005145:Face; D005260:Female; D005838:Genotype; D006200:Hair Color / Q000235:genetics*; D006736:Horses / Q000235:genetics*; D006824:Hybridization, Genetic; D008297:Male; D008957:Models, Genetic; D012042:Registries