Direct evidence for linkage of roan and extension loci in Belgian horses

A bay roan Brabant Belgian stallion (ERn/ ern) was bred to eight chestnut American Belgian mares (ern/ ern), producing 57 foals. Thirty foals were bay roan, 25 were chestnut, one was bay, and one was chestnut roan. The recombination rate was 0.035 +/- 0.024, indicating fairly close linkage between the roan (Rn) and extension (E) loci.