The Royal Welsh Show is to ban livestock from England from this year's event following the spread of the bluetongue virus.
In a statement, organisers said they "recognised the growing concern" around the recent outbreak.
Royal Welsh Agricultural Society (RWAS) said livestock entries of animals susceptible to the virus – particularly cattle, sheep and goats – will not be accepted from exhibitors located within a bluetongue virus restricted zone.
The zone is to be extended to cover the whole of England from 1 July before the annual show in Llanelwedd, near Builth Wells in Powys, on 21-24 July.
Animals that must travel through a restricted zone are also banned, effectively denying entry to any livestock from Scotland.
It will mean an estimated 40% fewer cattle competing at this year's show but reduces the risk of the "nightmare" of bluetongue reaching the show.
Bluetongue serotype 3 (BTV-3), mainly spread by midge bites, does not affect humans or risk food safety.
