Saying consumers want the change, General Mills on Monday announced it would suspend by August the use of milk produced from cows injected with a synthetic hormone in all Yoplait yogurt.

The hormone, known as rBST or rBGH, helps a cow produce more milk but has come under increasing scrutiny from consumers.

"While the safety of milk from cows treated with rBST is not at issue, our consumers were expressing a preference for milk from cows not treated with rBST, and we responded," Becky O'Grady, General Mills' vice president of marketing for the Yoplait brand, wrote in a statement.

The hormone, sold under the brand name Posilac, was first marketed by Monsanto in 1994. The drug was purchased by a division of Ely Lilly last year.

Farmers use the hormone in their herds because it increases milk production by about one gallon per day per cow. It's approved for use in cows by the U.S. Department of Agriculture, which says studies show it is safe for human consumption.

It has been banned in Canada, Australia, Japan and elsewhere. Studies showed its use has ill effects on cows, including increased incidence of mastitis, sometimes known as "turbo-udder," a condition in which the cow's mammary glands swell.

In 2007, supermarket chains including Kroger and Publix began dropping milk made with rBGH from their shelves. Starbucks no longer sells dairy products made from rBGH.

General Mills, based in Golden Valley, had net sales of $14.9 billion in its most recent fiscal year.

Matt McKinney • 612-673-7329