Effect of Corn Containing the Cry1F Protein on Performance of Beef Heifers Fed a Finishing Diet Based on Steam-Flaked Corn12

Corn (maize; Zea mays) lines with the Herculex I trait have been modified to express both the Cry1F protein from Bacillus thuringiensis subsp. aizawai and the phosphinothricin-N-acetyltransferase (PAT) protein from Streptomyces viridochromogenes. Hybrids containing event TC1507 express the Cry1F protein that controls European corn borer and certain other lepidopteran pests. Event TC1507 also expresses the PAT protein that confers tolerance to glufosinate-ammonium herbicides. The current study was conducted to evaluate the nutritional value of grain containing the TC1507 event by comparing the growth performance and carcass traits of beef heifers fed diets containing grain from a hybrid containing the TC1507 event to that of grain obtained from the near-isoline (control) as well as 2 nontransgenic commercial corn grain controls (Pioneer hybrids 33J56 and 33R77). Diets composed of steamflaked corn were individually fed to 80 beef heifers (360 kg) for 118 d. Dry matter intake, ADG, and G:F were not different (P > 0.05) between groups of heifers fed diets containing different sources of corn grain. Carcass traits, incidence of liver abscesses, and yield grade and quality grade were not affected by dietary treatment. In summary, growth performance and carcass characteristics of beef heifers were not significantly altered by feeding diets containing TC1507 corn grain vs. grain from its near-isoline or 2 other nontransgenic commercial corn grain hybrids.