My late father said that a white one with red hair around the ears might be genetically roan. I wonder if that works the other way--is a red one with white hair around the ears truly red? A leading breeder, who registered hundreds of Shorthorns, once had a white one sired by a red bull--I'd suspected that the "red" sire was one of those extremely dark roans with just the occasional white hair. Or could the sire have been red with white around the ears?
White heifer disease--our champion white bull in the 60's carried it. What a heartbreak to take two heifers from winning get (state show) and have neither of them ever breed. With more recent whites from other genetics, there was no problem--by then we did not keep back a white unless she had red ear hair.
One of the famous movie people once had a herd of 100% white Shorthorns. Probably not a good idea. The old Scotch breeders liked to use a white bull now and then to keep their reds from getting too pale--deeper reds resulted from having some roan or white not far back in the pedigree, at least that was their theory.