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Cows and Hops Could Prove to be a Good Combination

Hops growing on trellises in Corvallis, Oregon.

Hops growing on trellises in Corvallis, Oregon.

This post is part of the Science Tuesday feature series on the USDA blog. Check back each week as we showcase stories and news from the USDA’s rich science and research portfolio.

No, you’re not likely to see a herd of tipsy Holsteins belly up to the bar for happy hour. But scientists with USDA’s Agricultural Research Service (ARS) say a key ingredient in beer-making could become a valuable component in a cow’s diet:  hops.

Cattle, deer, sheep, goats and other ruminant animals depend on a slew of naturally occurring bacteria to aid digestion in the first of their four stomach chambers, called the rumen.  But ARS researchers Michael Flythe, Isabelle Kagan and Glen Aiken at the agency’s Forage Animal Protection Research Unit in Lexington, Ky., say some of the rumen residents, known as hyper-ammonia-producing bacteria (HAB), are jacking up production costs for farmers.

While beneficial bacteria are hard at work helping their bovine hosts break down plant fibers into cud, the HAB are hogging amino acids for a chemical process that not only produces ammonia, but also robs the animals of those same amino acids needed to build muscle tissue. To make up for the lost amino acids, farmers have to add costly high-protein feed supplements that often are not effective.

But the good news is that hops, the climbing female flower clusters that look somewhat like pine cones, can reduce HAB populations.  As a natural preservative, hops have been used for hundreds of years by brewers to limit bacterial growth.

In his research, Flythe put either dried hops flowers or hops extracts in cultures of pure HAB or a bacterial mix collected from the rumen of a live cow. Both the flowers and the extracts limited HAB growth and ammonia production.

The scientists say further research is needed on the value of supplementing traditional feed with hops.  In the meantime, don’t expect Bessie to pay for the next round!

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