Wal-Mart Stores, Inc. (NYSE: WMT) indicated last week that it would begin selling milk under its own private label brand ("Great Value") that is not sourced from cows that have been treated with growth hormones. There are already several brands of milk that have this feature (generally, the "organic" brands), but this is the first time I've seen a Wal-Mart store brand make a major move like this.

Growth hormones are administered to cows to increase their milk production, but critics argue that the injections lead to less healthy cows which are, in turn, more likely to be treated with antibiotics. It's been widely reported that most normal supermarket milk is sourced from cows that have been treated with artificial hormones, although without national testing and a complete statistical sampling, it's hard to tell which have been treated and which have not been.

Preventcancer.com even says that most European countries and Canada ban importation of U.S. milk for this very reason. So my question to Wal-Mart is this: is the new "Great Value" milk choice being offered nationally in all U.S. stores? If so, where is the list of your suppliers? It's hard to think that the world's largest retailer could instantly start offering hormone-free milk to its stores without turning the natural dairy industry on its head overnight. The retailer says it is bowing to consumer demand here, which is good. Still -- are there enough dairy suppliers that don't treat their herds with artificial hormones to cater to Wal-Mart's needs?