This would be the case even if a derogation from the European Commission allowed them to maintain use of the term ‘free range’ to describe their produce, they say.
The derogation, possible under EU egg marketing rules and which would have to be sought by the government, would most likely run for a limited period only, and there are fears it could expire long before any risk subsided.
“With avian influenza we are talking about a threat that could
go on for months,” said John Widdowson, vice-chairman of the British Free Range Egg Producers Association.
“If a decision is taken to close up houses then how long will they be closed for and how long would the derogation last?”
He warned there was a risk of sending out confusing messages to consumers.
“If hens are housed, then technically the eggs they produce would be barn eggs.”
Defra has said the evidence pointed to a low risk of avian flu entering the UK.
Not even when the Netherlands suffered an outbreak in 2003 did the UK house its free-range flocks.
The NFU said it would talk to its members about contingency plans to supply additional accommodation for flocks.
Pressure is likely to grow again on September 15, around the start of the migration season and the day when the Germans are planning to order their hens inside. Belgium and Denmark are likely to follow suit, depending on a review of the science and migratory patterns by EU experts.