Wichita ? The Kansas Department of Agriculture is studying a proposal to limit labels advertising milk and dairy products as coming from cows not injected with artificial growth hormones.

Recombinant bovine growth hormone, rbGH or rBST, is injected into cows to boost their milk production, typically by 5 to 15 percent.

Some dairy producers who don’t inject their cows with the substances label their milk as containing “no artificial hormones,” or “rbGH-free” or “rBST-free.”

But the dairy industry contends such labels are misleading, and pushed this year for state legislation making it unlawful to label any farm product with a claim that cannot be confirmed by a laboratory.

“What we are doing is trying to level the playing field for everyone with some level of guidance,” said Lisa Taylor, spokeswoman for the Kansas Department of Agriculture.

The department contends that lab analysis cannot confirm that a dairy product is free of rbGH or rBST, because cows produce the same hormones naturally.

Opponents contend a stricter labeling rule would make it harder for small and medium-sized producers to market their dairy products.

“This is really just an attempt by industry to make things difficult for those who aren’t using this artificial hormone,” said Mary Fund, spokeswoman for the Kansas Rural Center.

The proposed rule would let manufacturers label a product as coming from cows who were not supplemented with rBST, or something similar.