What methods are available for pig farmers to prevent boar taint as much as possible?

Surgical castration as it has been conducted for many years; the testicles of the young male piglet are removed.
Immuno-castration, the boar is two times vaccinated during the rearing with a substance which suppresses the growth of the testicles.
Optimal breeding conditions of boars: proper housing, genetics, nutrition, hygiene and rest in the barn and playing material for the animals.