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

A bay roan Brabant Belgian stallion ( ERnl ern ) was bred to eight chestnut Ameiican Belgian mares ( eml ern ), producting 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.