What is the best surface to prevent lameness in dairy cows?

While grass is the best support surface for cattle, in many places it cannot be used, particularly when climate conditions are too harsh for grass to grow or be maintained or in housing systems that do not support access to a grass surface. In such circumstances, what other types of surfaces can be used and what role do they have in either promoting or preventing lameness? Along with mastitis and infertility, lameness is one of the main welfare, health and production problems found in intensi