Biotechnology derived crops such as Bt corn have become commonplace on dairies today. In fact, Bt hybrids accounted for approximately 20-25% of corn acreage planted in the US in 2002. Despite the relatively widespread usage of biotechnology-derived crops, we continue to receive calls and questions about the effects of these crops for cows and consumers.

Recently at Iowa State University, we evaluated a new Bt corn variety containing a unique Bt gene (Cry1F) that was developed jointly by Pioneer Hi-Bred International, Inc. and Dow AgroSciences LLC. Hybrids containing this new technology (commercially known as Herculex™ I Insect Protection) provide protection against corn pests such as European corn borer and black cutworm, and we compared this new Bt corn to its non-Bt genetic counterpart as corn silage and grain for high producing dairy cows. In addition to European corn borer and black cutworm, Herculex I is labeled to protect the corn plant against southwestern corn borer and fall armyworm. Black cutworm and fall armyworm protection differentiate the Herculex I trait from the YieldGard® trait.

In our study, there were no appreciable differences in the nutrient composition of Cry1F Bt and non-biotechnology derived genetic counterpart hybrids. When dairy cows consumed silage and grain from these hybrids, there were no differences in their average milk, fat, and protein yields. Daily milk yields for the groups exceeded 85 lb. per cow during the two month-long feeding periods. Also, we detected no differences in dry matter intakes, efficiency of milk production, milk somatic cell counts, and physical and blood indicators of health for cows in these feeding groups.

Results from this study conducted at Iowa State University indicate that new corn hybrids containing the Cry1F Bt gene are as wholesome and nutritious for high producing dairy cows as are genetic counterpart hybrids that do not contain the novel Bt gene.

Marjorie A. Faust's study will be presented at the American Dairy Science Association conference in Phoenix, Arizona, in June 2003.