DENVER -

A Colorado-based grocery store chain recently announced it will carry only dairy products from farms where cows graze in pastures.

Natural Grocers by Vitamin Cottage claims grazing improves the health of cows, consumers and the environment.

Executive vice president Heather Isely says consumers envision dairy cows on pastures and don't realize that most animals are kept in barns. She says the company wants to encourage people to think more carefully about where their food comes from.

But Cornell University professor Tom Overton, an expert in dairy cow nutrition, sees Natural Grocers' push for pasture-raised dairy as mostly a marketing tool.

He says grazing doesn't significantly change the nutritional value of milk and that animals in barns can be just as healthy as those outdoors.