Safety Considerations Regarding Use of Btl 76 Maize as Broiler Feed

The use ofgenetically modified (GM) feed for animal production is expected to increase in the future. But acceptance of such feeds is being debated in the society. The question whether the process of genetic modification could have unintended effects on feed quality or nutrient composition of the grain is of great practical relevance. In addition, recent studies showed that native plant-DNA-fragments of different size couldbe associated with animal tissues. It was therefore of interest to study the way of inactivation of nucleic acids from feedstuff's in the digestive tract of chicken. For this purpose, feeding experiments with Btl 76 maize and its isogenic control were performed. Btl 76 maize hybrids express a gene that enables the plants to produce an insecticidal protein, which is similar to that produced in nature by Bacillus thurineiensis. Two kinds of feed with a portion of either 60% conventional or 60% Btl 76 maize were fed to broilers. Neither the nutrient composition of the maize grain and feed nor feed intake, bodyweight or feed conversion ratio showed significant differences between the two. treatments. The performance did not differ between the two groups of broilers. The maize-specific gene ivr (226 bp) could be detected in maize, feed and in digesta samples as far as the small intestine. The Bt-specific gene bla (479 bp) could only be detected as far as the crop. From this study it can be concluded that the two maize types can be considered as "substantially" equivalent as originally defined. The transgenic maize and its isogenic control maize had no detectable differences in effect on the performance and the metabolism of the chicken in this study. INTRODUCTION In recent years, agricultural biotechnology has produced several new varieties of crop plants with enhanced features such as protection against pests, diseases and herbicides or improved quality. Therefore, the use of genetically modified (GM) feed for animal production is expected to increase in the future. To date, 46% of the soya-products on the world-market, and 7% of the maize-products are transgenic (www.transgen.ch). In the year 2001 the area under crops for genetically modified plants increased from at least 19% to S2.6 million ha (www.transgen.ch). Therefore, more and more such products are becoming available for livestock feeding. However, genetically modified plants in the society is a controversy. The concerns regard the substantial equality of the plants, the risk of allergens or of antibiotic resistance transfers, the threat for the biodiversity and for non target organisms. Institute of Food Science and Nutrition. Laboratory of Food Microbiology, ETH Zurich, Switzerland.