Cloned Gene May Benefit Cattle Feeders,
By Ben Hardin
March 28, 1997
More lactic acid is good news for some, bad news for others.
Companies that manufacture lactic acid for food and industrial uses would
like to find a way to make greater amounts of the acid while cutting production
costs. But cattle feedlot managers would like to find a way to reduce the
lactic acid thats naturally produced in cattles stomachs, because
it means big headaches for them--and big stomachaches for the cattle.
Scientists with USDAs Agricultural
Research Service may be able to help both groups with a single discovery.
Lactic acid is produced naturally by the bacterium Streptococcus
bovis with help from an enzyme called lactate dehydrogenase. The
ARS scientists have isolated the gene
thats responsible for production of the crucial enzyme. Armed with that
information, the scientists could someday genetically manipulate S.
bovis to produce less lactic acid in cattle.
When cattle switch from a high-forage diet to a grain-rich finishing ration,
millions of S. bovis in the cattles rumen--a stomach
compartment--gobble up more glucose from the grain than they need and, in turn,
spew out an abundance of lactic acid. The animals can develop lactic
acidosis--a giant stomachache.
Sometimes life-threatening, lactic acidosis inhibits animals weight
gain and can lead to liver abscesses and other abnormalities. The result:
Losses of up to $100 million annually for the U.S. cattle feeding industry.
At the other end of the spectrum, commercial manufacturers of lactic acid
also could benefit from manipulation of the lactate hydrogenase gene.
To produce more lactic acid where its wanted--for the manufacture of
industrial products such as biodegradable plastic--the ARS scientists hope to
transform microbial species other than S. bovis to make more lactic
acid. Theyve already genetically engineered multiple working copies of
the lactate dehydrogenase gene into the bacterium Escherichia
Scientific contact: Michael A. Cotta, USDA-ARS,
National Center for Agricultural
Utilization Research, Peoria, Ill., phone (309) 681-6273, e-mail