Debate over the authenticity of one of the nation's largest organic milk brands continues to grow, and has made its way to the store shelves.

PCC Natural Markets, a Seattle based organic retail cooperative decided last month to no longer carry Horizon's Happy Cow brands in its stores, claiming that the products do not meet organic standards due to the farming practices of some of Horizon's largest raw milk suppliers.

PCC's move is the latest in a string of boycotts from grocers, including the Boulder Co-op Market, and organizations, such as the Organic Consumers Association, who claim Horizon's farms are too large and the company does not give its cows enough access to pasture. PCC's boycott will include related brands such as Silk and WhiteWave soymilk. All three brands are owned by Boulder, Colo.-based WhiteWave Foods, a division of Dean Foods, Dallas.

The PCC boycott came the same week that USDA Compliance received a formal complaint from the Cornucopia Institute of Wisconsin, the organization that has been publicly questioning Horizon's practices for more than a year.

A spokesperson for Horizon says the complaint is without merit and that the company will prevail. Horizon also points out that 80% of its milk comes from more than 300 family farms, and that the concerns raised about confinement and pasture access have nothing to do with those farms, but rather with a small number of very large farms.