Stephen Koontz, an agricultural economist at Colorado State University, said beer brewers and livestock feeders alike benefit, The Denver Post reported.
"The distiller or brewer has a lot of byproduct," Koontz said. "Conveniently, cattle do well with this feed. So it is a good match."
Corn prices have doubled in the past six years as corn previously used for livestock feed now goes to ethanol production.
The Post said the process of beer brewing and ethanol production removes starches and sugars from corn but the remaining spent grains provide protein and fiber that can supplement corn for cattle feed.
Some brewers receive about $5-$10 a ton for the wet grains while others give the brewing byproduct away.
"They say that Colorado is the Napa Valley of beer, and there are a lot of breweries here producing a lot of spent grain," said Joe Schiraldi, vice president of brewing operations for Boulder-based Left Hand Brewing.
Craft brewers lack storage for much used grain, which can slow production if it's not disposed of.
Rex Beall, an owner and manager of Ulrich Farms, a cattle-feeding operation near Platteville, said the non-alcoholic byproduct accounts for about a quarter of his cattle's feed.
"Today's market has changed so much because of corn prices," Beall said. "There is value to us in using the brewers' grains."