However, data from the voluntary scheme showed it is not possible to ensure PI removal from farms and BVD eradication through voluntary means.
Fodd bynnag, dangosodd data o'r cynllun gwirfoddol nad oes modd sicrhau bod anifeiliaid sydd wedi'u heintio'n barhaus yn cael eu symud o ffermydd ac nad oes modd dileu BVD drwy ddulliau gwirfoddol.