Thanks for the replies. Isn't the roan test from UC Davis just checking on a roan gene? Meaning that not all roans will test for that particular gene? Do you have experience with this test? Did you find it accurate?
BTW, the folks at Animal Genetics gave me practical way to observe the roan genes. If a roan horse gets cut, the hair will grow back the color of the body, without the white hairs mixed it. It does appear that way on one of my roans, but I was looking for a way to test a foal - without him getting cut, lol.
Thanks again, I guess my possible bay roan app colt will have to stay 'possible' for now. I'll look in to the US Davis test.