The Western Canada PRRS-Free Herd Certification Pilot Project, an initiative of the Canadian Swine Health Board, provides a protocol under which suppliers of pigs or semen will be able to certify their stock is PRRS free.
Basically they have to test at least 60 different animals in their herd to hit the magic target or the points required to achieve certification and after that they'll have to do ongoing testing. For a boar stud it'll be a fairly frequent testing. It has to be almost weekly or biweekly any way and the reason for that is because those studs are sending out semen to farms on a regular basis and we want to make sure that any break with disease in a boar stud will be caught within a week or within ten days. Breeding stock farms send out groups of animals on a somewhat less regular basis so they don't have to test quite as frequently in order to make sure that you catch any animals before they're shipped out.