With Sainsbury's, the Co-op and Waitrose already no-go areas for cage eggs, the retail sector is already half-way to a prediction that free range would rule the roost on supermarket egg shelves by 20120, according to a Poultry World report on Farmers Weekly Interactive (FWI).

The forecast was made just over a year ago at the height of the Jamie Oliver tirade against intensive production. At that time, only the Co-op had banned cage eggs with Sainsbury's following this February. Both Waitrose and Marks and Spencer had banned cage eggs some years ago.

At Tesco, shelf-space for barn, free-range and organic eggs has been increased, while that for cage flocks has been reduced. "Many of [our customers] tell us they are on a tight budget and rely on us to provide affordable, good quality food," said a spokesman, adding that Tesco would be moving in 2012 to eggs from enriched cages which have significant welfare advantages over the conventional.

Morrisons told Poultry World: "We have made good progress towards achieving our stated commitment to selling own label cage-free shell eggs by 2010."

Cage eggs are still the most popular line at Asda and account for 49 per cent of total shell egg sales, said spokesman James Maxton.

"The reality is that, while some customers are choosing to trade up to free-range eggs, many others can't afford to make that choice. Our job is to make sure we provide everyone with the best quality product at the best possible price, and that's exactly what we're doing. We are confident that will have enough UK stock of free-range eggs and that we won't need to import any.

"We are not one of the chains selling down-sized free-range eggs," he added, referring to unconfirmed reports that one of the major retail chains was seeking small free-range eggs and asking packers if they could down-size part of its supply of mainly larger eggs. It was part of a bid to bridge the retail price gap between cage and free range and use the smaller eggs in mixed size packs.

The small egg issue was discussed at the March meeting of the East Midlands poultry discussion group. One of the speakers, Ian Mackinson, poultry products manager of Premier Nutrition, said one leading retailer, who he did not name, was hoping to produce a mixed-weight pack at minimal extra cost.

"Once customers have made the switch, I guess they will phase out cage eggs and revert to more typical offerings of free-range eggs," he suggested.

None of the supermarkets contacted by Poultry World in April admitted to asking packers to down-size free-range eggs.

The cage-egg free Co-op has a 'Simply Value' free-range egg 10-pack, as a minimum net weight containing both small and medium. Egg buyer, Rachel Marshall, said the group was able to get enough free-range eggs in the weights required and, as long as the exit from cage eggs was planned and timed properly in terms of laying down free-range production, there should not be a shortage of free range.

"Barn eggs are seen as the basic egg and carry the same price as the previously sold cage eggs," explained Sainsbury's egg buyer, Finbar Cartilage. A value range of eggs under packer's branding allow customers to buy a mixed weight product at a sharper price point and a three have been promotion to encourage customers to switch to free range.

"Up until the changeover, approximately 30 per cent of our eggs sold were from caged farms and this is a number that has not changed in recent times. We are selling roughly the same number of eggs now as beforehand," he said.

"Aldi only stocks Lion UK eggs and specifies a medium size for free range," a spokesman told Poultry World. "We work closely with our suppliers when sourcing products and developing packaging and do not mix small and medium egg sizes to reduce pack prices.