Members of the assurance scheme who have flat deck systems have been told to install 8cm of perching per bird by August 2018.

Perching was one of a number of proposed changes tabled by Freedom Foods last July but implementation was delayed after BFREPA raised serious concerns over the lack of a proper consultation process.

BFREPA’s chief executive Robert Gooch said: “We are opposed to this requirement on a number of levels with hen welfare being our primary concern.

“The evidence we have seen from Bristol University shows that fitting large amounts of aerial perching can lead to an increase in keel bone damage to hens. It’s a welfare concern that we would expect any organisation – particularly the RSPCA – to recognise.

“At a practical level this will also cause huge difficulties for those retrofitting perches to sheds that weren’t designed for them and are likely to hamper daily management procedures.”

A number of BFREPA’s members have carried out voluntary trials to measure the impact of perching in commercial situations.

They have found that installing more than 6cm of perching per bird has had no measurable benefit for the birds.

Mr Gooch said: “We have offered to carry out additional research with the RSPCA to find an amount of perching that improves bird welfare. That invitation remains open.”

Between 30 per cent and 40 per cent of BFREPA’s members are understood to be affected by the changes – approximately 250 producers.

“Producers using flat deck systems are already competing in a tough market and are generally operating at a smaller scale compared to multi-tier producers,” Mr Gooch said.

“Ramping up additional costs and requirements on these producers is only going to add pressure to these businesses and dissuade them from investing in their futures.”

Mr Gooch added that he was pleased that the RSPCA has listened to BFREPA’s concerns and withdrawn the requirements for specific perching configurations on multi-tier systems.