Features Applications Beef
Hops help reduce ammonia produced by cattle

April
21, 2010, Lexington, KY – An Agricultural Research Service (ARS) scientist may
have found a way to cut the amount of ammonia produced by cattle.


April
21, 2010, Lexington, KY – An Agricultural Research Service (ARS) scientist may
have found a way to cut the amount of ammonia produced by cattle.

To
do it, he’s using a key ingredient of the brewer’s art – hops.

Cattle,
deer, sheep, goats and other ruminant animals depend on a slew of naturally
occurring bacteria to aid digestion of grass and other fibrous plants in the
first of their four stomach chambers, known as the rumen.

The
problem, according to ARS microbiologist Michael Flythe, comes from one group
of bacteria, known as hyper-ammonia-producing bacteria, or HABs. While other
bacteria are helping their bovine hosts convert plant fibers to cud, HABs are
breaking down amino acids, a chemical process that produces ammonia and robs
the animals of the amino acids they need to build muscle tissue, according to
Flythe, who works at the ARS Forage Animal Production Research Unit (FAPRU) in
Lexington, Ky.

To
make up for lost amino acids, cattle growers have to add expensive and
inefficient high-protein supplements to their animals' feed.

According
to Flythe, hops can reduce HAB populations. Hops, a natural preservative, were
originally added to beer to limit bacterial growth.

Flythe
put either dried hops flowers or hops extracts in either cultures of pure HAB
or a bacterial mix collected from a live cow's rumen. Both the hops flowers and
the extracts inhibited HAB growth and ammonia production.

Flythe
and FAPRU plant physiologist Isabelle Kagan have completed a similar project
with more typical forage. They recently identified a compound in red clover
that inhibits HAB. Results of that study were published recently in Current
Microbiology.

Flythe
also collaborated with FAPRU animal scientist Glen Aiken on a study in which
hops had a positive effect on the rumen’s volatile fatty acid ratios, which are
important to ruminant nutrition.