Wal-Mart Stores Inc. is selling milk free of bovine growth hormone under its own label, part of an expansion of organic and health-oriented goods at the world's biggest retailer.

The milk will be sold under the Great Value brand at Wal-Mart and Sam's Club stores, the company said.

Bentonville, Ark.-based Wal-Mart said it asked suppliers not to use the hormones, which increase a cow's milk supply, in response to customer demand.

Wal-Mart has expanded its selection of organic food and clothing as it seeks to boost sales at a time of slowing consumer spending, while reducing waste and energy use. Last year, the company named an executive to oversee the development of products that are safer for the environment.