Spent grain, which is high in fiber and protein, is beneficial for cows and disposing of it to local dairy farms is considered environmentally and cost friendly. However, the Food and Drug Adminstration lately proposed a rule that would classify beer brewers that sell spent grain to farms as "animal feed manufacturers" and they would no longer be exempt from having to dry and package the spent grain before they could sell it.

The regulation is part of the Food Safety Modernization Act which was signed by President Barack Obama  in 2011.

"That would be cost prohibitive," Scot Mennen, Widmer Brother's vice president of brewery operations, said. "Most brewers would have to put this material in a landfill."

Brewers are finding it difficult to understand the need to change an arrangement that's been there for centuries. "This is regulating a problem that does not exist," said Van Havig, Gigantic Brewing Company masterbrewer.

Director of surveillance and compliance in the FDA's Center for Veterinary Medicine Daniel McChesney agreed the FDA does not know of any problems with the arrangement and explained that "we are trying to get a preventative mode." The proposed regulation aims to prevent foodborne illnesses in both people and animals.

The new requirements could cost millions to cover for equipment and installation and force brewers to increase beer prices. Jerome Rosa, a farmer in Oregon, buys around 20 tons of spent grain per week to feed 300 cows.

"I pay virtually nothing. But it's like putting honey on your cereal. It makes the cows want to eat more and we notice it in their production," Rosa said.

However, his feed expenses could go up without spent grain and it would add to the price of milk as well.

As per the beer Industry, most big beer brewers ship spent grain by the bulk with almost three million tons a year going out. Around 90 percent goes to livestock. A gallon of beer could yield a pound of spent malted barley husks, which are heated to around 170 degrees Fahrenheit, killing any contaminants during brewing.

McChesney said the FDA did not foresee the reaction and is now reconsidering the rule. The federal agency will accept comments for the revision of the proposal, which will be finalized on August 2015.