Specialist poultry and specialist pig farms are not surveyed, as there are very few farms from which to survey and obtain reliable results.
Nid yw ffermydd dofednod arbenigol a ffermydd moch arbenigol yn cael eu cynnwys yn yr arolwg gan mai ychydig iawn o ffermydd sydd ar gael i'w holi a chael canlyniadau dibynadwy.