Lincoln, Nebraska
November 10, 2003
The
latest University of Nebraska
research confirms that feeding or grazing genetically modified
corn has no effect on livestock performance.
These
studies involved Bt corn for rootworms and Roundup Ready corn.
Results reinforce earlier findings on the feed value of
genetically modified crops by scientists at Nebraska and at
other land-grant universities, said Animal Scientist Galen
Erickson.
The
bottom line for livestock producers is they can expect the same
livestock performance whether they feed currently available
genetically modified corn or conventional corn, he said.
NU
Institute of Agriculture and Natural Resources animal scientists
have evaluated performance of livestock fed or grazed on
genetically modified corn for the last three years to provide
information on these new types of corn, he said. Sixty percent
of the U.S. corn supply is fed to livestock.
"It's
important that if we change corn traits that we do not decrease
the feeding value," Erickson said. "Bt and Roundup Ready corn
are very advantageous from an agronomic point, but we needed to
research this to ensure that the feed value was not negatively
impacted."
Feeding trials for beef, dairy and swine were conducted at NU's
Agricultural Research and Development Center near Mead, Neb.
One
experiment found no difference in steer performance among steers
that grazed corn stalks from either Bt corn for rootworms,
Roundup Ready corn or conventional corn during a 60-day grazing
period.
In a
2001 study, steers showed no preference for Bt or conventional
corn. During the grazing period, 47.5 percent of the steers were
observed grazing Bt residue, while 52.5 percent were observed
grazing conventional cornstalks.
Producers sometimes report that cattle spend more time grazing
conventional than Bt cornstalks. However, Erickson said this
apparent preference probably is because there's more corn left
after harvest in conventional corn fields with insect damage.
In
two finishing trials, 200 steers were fed rations containing
either Roundup Ready corn or a conventional but genetically
similar hybrid, and 200 crossbred yearling steers received Bt
corn for rootworms or genetically similar conventional corn.
Animal performance and carcass data for these trials showed no
significant differences.
"Overall, performance was not negatively affected in the corn
residue grazing or feedlot experiments, suggesting that the corn
rootworm-protected hybrids and Roundup Ready corn hybrids are
similar to conventional corn grain and residues when utilized by
beef cattle," Erickson said.
In an
experiment with swine, NU Swine Nutritionist Phil Miller
compared pig growth and percent lean in pigs fed Bt corn for
rootworms or conventional corn. In another study, they compared
nutritional value and nitrogen digestibility for young pigs fed
Roundup Ready corn and those fed conventional corn.
Neither study revealed significant differences, Miller said.
Researchers evaluated 72 barrows and 72 gilts for the Bt study
and 12 barrows for the Roundup Ready study.
Results showed Bt corn does not affect pig performance and that
Roundup Ready corn can be fed to young pigs without affecting
nitrogen or energy digestibility, Miller said.
Two
dairy studies also were conducted to evaluate the effect of
Roundup Ready corn and Bt corn for rootworms on feed intake and
milk production. Findings showed similar performance for
genetically modified and conventional corn as measured by
efficiency of milk production for lactating dairy cows.
These
studies were conducted in cooperation with IANR's Agricultural
Research Division. |