November 12, 2003

 

 

US Study Says Use of GM or Conventional Corn Has No Effect On Livestock Performance

 

Feeding or grazing genetically modified Bt and Roundup Ready corn has no effect on livestock performance, according to new research from University of Nebraska.

 

Three years of feeding trials for beef, dairy and swine were conducted at NU's Agricultural Research and Development Center near Mead in the United Kingdom.

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, says animal scientist Galen Erickson.

The results reinforced earlier findings on the feed value of genetically modified crops by scientists at Nebraska and at other land-grant universities, he says.

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.

"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."

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% of the steers were observed grazing Bt residue, while 52.5% was 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 cornfields 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 pig performance was not affected by Bt corn and that Roundup Ready corn can be fed to young pigs without affecting nitrogen or energy digestibility, Miller said.

In addition, two dairy studies 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.