Wal-Mart's UK supermarket chain Asda has announced that it will switch 500,000 hens from battery cages into open barns by 1 May by changing the way in which it sources standard own label, fresh eggs.

For the first time each hen will be able to lay its eggs in quiet individual nest boxes within an open barn, the company said. The move means Asda will sell 140m fewer battery eggs in the next year alone.

Each of Asda's 277 stores nationwide now has a comprehensive selection of barn and free range eggs on sale. Over the past 12 months the supermarket has seen sales of barn and free range eggs increase significantly as more and more consumers opt for higher welfare British eggs.

Chris Brown, agriculture strategy manager at Asda said: "Sales of free range eggs are growing at 22% - a faster rate of growth than any other major UK food retailer. In fact, we now sell three times more free range eggs than Waitrose."

Asda has been working closely with its British egg suppliers over the past year to develop new methods of egg production. As a result it will no longer use battery production for any of its standard own label fresh eggs.

John Avizienius, RSPCA senior scientific officer, said: "This is great news for animal welfare. We are delighted that Asda has responded to consumer demand in taking this initiative and hope to see other retailers who stock a high number of battery eggs following their lead."

Asda Smartprice eggs (Asda's own label value range) are still produced from caged hens.