Here's part of the article I read. It's about myths about hooves... from horsechannel.com
Myth: White hooves are softer and have more problems than black feet.
The color of the hoof is influenced by the color of the skin above it, so if a horse has white markings directly above the hoof, the hoof itself may carry the same pigmentation. Many people believe that hooves with black walls are stronger than hooves with white walls.
Master Farrier John Burt owns and operates the JDC School of Basic Farrier Science near Texarkana, Ark. He is a member of and tester for the Brotherhood of Working Farriers Association (BWFA) and a 2001 inductee to the BWFA Hall of Fame.
John says, "There is no quality difference on the same horse, no scientific data to sustain any difference. The white and the black hoof are both designed the same structurally; the texture and quality of the hoof is the same."
One of the foremost experts in his field, Doug Butler, Ph.D., of LaPorte, Colo., is the author of The Principles of Horseshoeing, one of the most widely used texts on horseshoeing in the world. He also has 30 years of teaching experience and acts as a consultant and lecturer on horseshoeing. In 1976 while doing research at Cornell University, he conducted a study on white versus black hooves by taking squares of hoof material and crushing them in a compressor.
"There was no difference between black and white," he agrees. "The main difference was in moisture content: The softer hooves fell apart easier." He notes that genetics also play a role in hoof strength. "Some Paint Horses have extremely brittle white hooves and others don’t. Appaloosas seem to have extremely strong feet, no matter what color; genetic propensity seems to be more important than the color of the hoof."