Spent grain from breweries feeds a lot of animals on farms and ranches. Credit: www.valiantbrewing.com

In 2013, New Belgium Brewing, the Fort Collins, Colo.-based purveyor of libations like Fat Tire and Ranger, whipped up exactly 792,292 barrels of beer. Considering each barrel is capable of filling somewhere in the range of 60 six-packs, that production made for plenty of happy drinkers (including, on more than one occasion, yours truly).

But New Belgium also satisfied non-human consumers, too, by selling 64 million pounds of “spent grain”—the ingredients left behind after the brewing process—to beef and dairy farmers, who feed the porridge-like substance to their cows.

“For hundreds of years, brewers have had this great symbiosis with farmers,” says Bryan Simpson, New Belgium’s director of media relations. “It’s a very elegant system.”

While many operations give away their used grains, selling the stuff can be a lucrative sideline: Spent grain goes for about $50 per ton nationwide, and total annual sales add up to around $160 million (most of it to the big boys, Anheuser-Busch and MillerCoors). Now, though, brewers claim this centuries-old harmony is threatened by new Food and Drug Administration rules that could make it harder for beer-makers to sell or donate their spent grain as cattle feed.

The proposed regulation stems from the Food Safety Modernization Act (FSMA), legislation designed to prevent food contamination. That’s a worthy goal: Salmonella and E. coli outbreaks are distressingly common, and the Centers for Disease Control and Prevention say that 48 million people are sickened—and 3,000 killed—by food-borne illnesses annually. The FSMA seeks to reduce that toll through measures like increased inspections and quality control for food imports, and the law drew praise from food safety advocates when it was signed in 2010.

While no one disputes that our food safety systems are in need of overhaul, not everyone is enamored with the new law. In November, Mother Jones agriculture critic Tom Philpott warned that inflexible regulations could impose “a significant and possibly devastating burden to small and midsize (food producers).” One California farmer suggested the law was pushing a “sterility paradigm” that failed to recognize the health benefits of microbes.

No one is more apoplectic than brewers, whose anger is targeted at a proposed rule that would require animal-feed producers to identify and avoid potential contamination hazards. It’s not yet entirely clear what breweries would have to do to mitigate those contamination risks; while some beer-peddlers fear the FDA is going to force them to dry and pre-package their grains,Twin Cities Business reports the agency is primarily concerned with how the feed is stored and transported—in other words, the cleanliness of silos and trucks. While many small breweries, or brewers who donate their grains, would likely be exempt from some of the rule’s requirements, the Beer Institute, an industry lobby group, estimates that compliance could cost big operations more than $13 million.

In the West, home to seven of the 10 brewery-densest states, restrictions on beer-related activities are likely to be especially unpopular. Little wonder, then, that some of the heaviest pressure against the FDA has been leveled by Western politicians.

“I don’t know everything about beer, but I do know when a federal agency acts like it has had one too many,” quipped Oregon Sen. Ron Wyden, a Democrat, who’s urging the agency to throw out its current proposal. And Sen. Mark Udall, a Colorado Democrat, recently penned a letter to FDA commissioner Margaret Hamburg asking her agency to review whether feeding spent grains to cattle presents a legitimate public health hazard. (Although the contamination of cattle feed from spent grain is theoretically possible, beer industry leaders say there’s never been a recorded incident.)

The situation may even spur legislative action. Colorado Rep. Cory Gardner, a Republican, is among the sponsors of the Sustainable Use of Spent Grains Act, which would exempt breweries from the rule. The grain issue is apparently so dire that it’s forced Gardner, introducer of the “Oil Above All” act, to sponsor a bill with “sustainable” in its title.

Not only would the FSMA regulation place a financial burden on breweries; New Belgium’s Simpson says it could produce unfortunate environmental consequences for an industry famous for its stewardship practices. Right now, New Belgium has a 99.9 percent diversion rate, meaning that practically none of its waste ends up in a landfill. If it becomes unprofitable to sell spent grain, though, the stuff could get thrown away—“a worst-case scenario,” says Simpson.

And what about the farmers who depend on the stuff? Justin Wertz, partner at El Dorado Cattle Co. in Durango, Colo., told the Durango Herald that without the free grain his company gets from nearby Ska Brewing, he’d likely go out of business. “It’s unbelievable, almost a complete feed,” he said. “It’s really high in protein as well as a bunch of other nutrients.”

Perhaps recognizing that you don’t mess with Americans’ beer and burgers, the FDA, has promised to submit a revision to the rule that’s “responsive to the concerns expressed.”

Ben Goldfarb is an editorial intern at High Country News, where this was originally published. The author is solely responsible for the content.