How do you prevent cows from getting cysts on their ovaries?

There really is no medication or feed system that will prevent cows from getting cystic ovaries, though over conditioning (where cows are too fat to be considered normal condition) may be a factor in a cow getting cystic ovaries. But scientifically there is (as of yet) no known causes of how cows get cysts on their ovaries, nor how it can be prevented with the exception of culling them out.