I've heard that putting corn starch/something like that on white spots for SHOWS gets white markings even whiter, and for special occasions you could probably use it to get a few grass stains out of their coat, but I don't know how good that would be for every day. Also, for growing out/thickening manes and tails? It helps if you don't brush them daily, just use a bit of oil and rub it through on bad hair days to get the tangles out, and just finger comb it. Brushing or combing them daily causes breakage and will just THIN the hair. Your horse is beautiful, btw.