Effect of feeding corn modified to contain a unique amylase on performance and carcass characteristics of feedlot steers1

A new corn hybrid has been developed through genetic modification that expresses a thermotolerant α-amylase (CA3272) that is able to process the corn starch for commercial ethanol production without the need for the addition of exogenous α-amylase. Because this amylase may improve ruminal starch digestibility and subsequently enhance performance of feedlot cattle, the objective of this research was to determine performance responses in feedlot cattle fed different concentrations of CA3272. Seventy-two Angus cross yearling steers (initial BW 349 kg ± 1.1 kg) were allotted by BW to 3 treatments to determine the effect of CA3272 concentration (0, 10, and 20% of dietary DM) on growth performance and carcass characteristics of feedlot steers. Steers were slaughtered after 131 d on feed. Final BW was similar among treatments (P ≥ 0.51). Average daily gain, DMI, and G:F did not differ (P ≥ 0.18) among cattle fed 0, 10, or 20% of dietary DM as CA3272, respectively. Hot carcass weight and dressing percentage did not differ among treatments (P ≥ 0.48). Longissimus dorsi area, twelfth rib fat thickness, marbling score, and percentage of cattle grading Choice or better did not differ (P ≥ 0.13) among cattle fed 0, 10, or 20% of the diet DM as CA3272. In conclusion, corn genetically modified to contain amylase has no effect on performance and carcass characteristics of feedlot steers when fed at a rate of 10 or 20% of dietary DM.