BOSTON (AP) – Two Massachusetts dairies, in a bid to compete with organic milk producers, are demanding that regional farmer cooperatives supply them with milk from cows that have not been injected with synthetic growth hormones.

Over the next few weeks, Hood, which operates a plant in Agawam, and Dean Foods, which operates the Garelick plant in Franklin, plan to begin shipping bottled milk to stores with labels that read “no artificial growth hormones.”

“The phenomenal success of organic milk, with growth rates of 20 percent or more, is driving our demand for milk from cows not treated with artificial growth hormones,” John Kaneb, the chief executive of Chelsea-based H.P. Hood, told The Boston Globe in an interview published Monday.

Nationally, sales of organic milk have doubled over the last three years to $1.1 billion, according to the Organic Trade Association in Greenfield, despite the fact that organic milk costs $6 to $7.50 a gallon, compared to $2.50 to $3.50 for conventional milk.

In late 2003, Oakhurst Dairy in Maine and Monsanto, a maker of growth hormones, signed an agreement to resolve a lawsuit that Monsanto had filed over Oakhurst’s labeling and marketing of its milk.

Monsanto’s lawsuit said Oakhurst’s claim that its farmers don’t use artificial growth hormones in their milk production was misleading and implied that something is wrong with growth hormones.

Under the agreement, Oakhurst was allowed to use milk labels that read, “Our Farmers’ Pledge: No Artificial Growth Hormone Used.” Its previous label did not have the word “used.”

Labels were also to carry a message saying the U.S. Food and Drug Administration had found no significant difference in milk from cows treated with growth hormones.

Smaller dairies have been marketing conventional milk produced without synthetic hormones, but the changes taking place now in southern New England represent the first large-scale conversion in the country, the Globe reported. Marguerite Copel, a spokeswoman for Dallas-based Dean Foods, said Dean intends to see how consumers react to its new Garelick milk before expanding its hormone-free operations.

“Even though conventional milk is completely safe, and Posilac (the brand name for synthetic hormones marketed by Monsanto Corp. of St. Louis) is completely safe, some people don’t feel comfortable with it,” Copel said.

Under federal standards, organic milk is from cows not treated with artificial growth hormones that boost milk production. Also, the cows are fed only organically grown food, and can graze in pastures.

Since there is no test that dairies can use to distinguish between artificial and naturally occurring growth hormones, processors are asking farmers to sign affidavits stating that they don’t use artificial growth hormones.

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