Effect of Feeding DAS-59122-7 Corn Grain and Nontransgenic Corn Grain to Individually Fed Finishing Steers1

An experiment was conducted to evaluate feeding transgenic corn containing the cry34Ab1 and cry35Ab1 genes from a Bacillus thuringiensis strain and the phosphinothricin acetyltransferase (pat) gene from Streptomyces viridochromogenes to finishing cattle compared with nontransgenic corn. Expression of the cry34Ab1 and cry35Ab1 genes confers resistance to corn rootworms, and the pat gene confers tolerance to herbicides containing glufosinate-ammonium. Sixty crossbred steers (396 kg) were individually fed either transgenic corn (DAS-59122-7; 59122), a near-isogenic, nontransgenic control (Control), and a conventional, nontransgenic corn for 109 d to evaluate nutritional equivalency (20 steers/treatment). The corn was coarsely rolled (geometric mean diameter = 4,200 µm) and treatments were offered in the finishing diet at 82% of diet DM. Gain (P = 0.38) and G:F (P = 0.80) were similar between 59122 and Control with a tendency for a difference in DMI (P = 0.08). When adjusted using the statistical analysis of false discovery rate, DMI, ADG, and G:F were not different between Control and 59122 (P > 0.33). No differences were observed between Control and 59122 for HCW, marbling score, LM area, fat depth, or calculated USDA YG (P > 0.12). The genetically modified corn DAS-59122-7 was nutritionally equivalent to a near-isogenic control when fed to finishing steers. Feeding corn grain containing these transgenic traits did not influence steer performance or carcass quality.