Cows will soon have a better
chance of getting their needed protein.
Scientists with the Agricultural Research Service recently discovered
an
environmentally friendly way to reduce the protein breakdown that
occurs
when forage crops like alfalfa are processed into silage, the winter
feed of many livestock.
Because it's high in protein, alfalfa is an ideal crop for livestock.
Unfortunately, when it's processed by storing and fermenting its
clippings in silos, up to 85 percent of alfalfa's protein breaks down
into nonprotein nitrogen, which can't be used as efficiently by the
cows' bodies.
ARS plant physiologist Ronald Hatfield, agricultural engineer Richard
Muck and molecular biologist Michael Sullivan have found an answer to
the problematic breakdown of protein in--of all things--red clover and
potato skins. The scientists work at ARS' U.S. Dairy Forage Research
Center in Madison, Wis.
Red clover contains large amounts of an enzyme called polyphenol
oxidase, or PPO. When red clover is chopped up, its cells release the
PPO. When the PPO is exposed to oxygen, it reacts with caffeic acid
naturally present in the clover and forms o-quinone molecules. These
molecules bind to the enzymes that cause the breakdown of red clover's
protein, thereby keeping more protein intact.
Alfalfa has significantly lower levels of PPO. So to take advantage of
this PPO-caffeic acid combination to protect alfalfa's protein,
Sullivan
and ARS plant pathologist Deborah Samac "borrowed" the PPO
gene from red
clover and inserted it in alfalfa plants. When the altered alfalfa
plants were chopped and treated with caffeic acid, they had 15 percent
less protein degradation after two weeks than did untreated alfalfa
plants.
Caffeic acid is present in high concentrations in a variety of fruits
and vegetables, most notably potato skins, a common agricultural waste
product. The scientists are working with different potato processing
plants to see how easy it would be to extract large amounts of caffeic
acid from leftover skins.
