Monsanto is trying to sell the division that makes artificial growth hormones (Prosilac) for dairy cows, according to press reports. This could be seen as a response to consumers, who uniformly seem to avoid milk treated with growth hormones. Wal-Mart, Kroger and Publix sell house brands that feature milk from untreated cows. Dean Foods, the nation's largest bottler, also sells milk only from cows who haven't consumed Prosilac.Monsanto introduced the hormone in 1993, making it one of the first applications of genetic engineering in food production. A 2007 survey found that only 17 percent of the nation's milk cows were using Prosilac. Monsanto has tried to keep milk labels from saying whether the product comes from untreated cows. Pennsylvania's secretary of agriculture banned these labels after heavy lobbying from Monsanto, but his decision was overturned by the governor after protests from consumers.