Ferdinand, winner of the 1986 Kentucky Derby, is a chestnut horse. Yet both of his parents were bay or brown. Furthermore, each of his four grandparents were also bay or brown. First of all - one needs to understand how a horse gets its color.
Every horse possesses two color genes, having received one gene from each parent.
For a list of known pure breeding bay stallions, go to Pure Breeding Bays . It MUST have received one chestnut gene from each parent. We've just finished creating a page which explains grey very well.