Reduction of Escherichia coli O157:H7 in Finishing Cattle Fed Corn Genetically Modified to Produce Increased Concentrations of Alpha Amylase in the Corn Kernel.

Cattle are recognized as the principal reservoir for O157:H7 and preharvest food safety efforts often focus on decreasing shedding of this pathogen in cattle feces. Enogen corn (EC; Syngenta Seeds, LLC) is genetically modified to produce enhanced concentrations of α-amylase in the corn kernel endosperm. Research has demonstrated improvements in feed efficiency for cattle fed EC and research has not yet explored whether improved digestion impacts foodborne pathogen populations in cattle. Therefore, this study explored effects of finishing diets containing EC on O157:H7 prevalence in cattle. A 2 × 2 factorial experiment was conducted with steers ( = 960) fed diets consisting of 2 types of silage (EC or Control) and grain (EC or Control), fed daily . Steers were grouped into 12 blocks by incoming body weight, blocks were randomly assigned to one of four pens, and pens were randomly assigned to one diet. Cattle were sampled using rectoanal mucosal swabs in cohorts of 298-337 cattle per day, for a total of 3 sampling days (15-16 days apart). O157:H7 prevalence rates ranged from not detected (0/75) to 10.0% (8/80) depending on sampling day. Tests for the silage × corn interaction, and the main effects of silage and corn, were not significant ( > 0.05); however, EC reduced the odds of O157:H7 prevalence by 43% compared to the control corn diet ( = 0.07). Diets containing EC tended to decrease O157:H7 prevalence in feedlot cattle; however, this reduction was not significant. Before a conclusion can be drawn about impact of EC on O157:H7 in cattle, further research is necessary to (1) determine if this tendency is due to increased alpha amylase activity and (2) elucidate impact on O157:H7 prevalence and concentration, as well as a possible mechanism of action.