Genetically Engineered Feed: Impact on Animal Performance, Health and Products

Genetically engineered (GE) feed crops became widely adopted following their introduction in 1996 and today more than 90% of sugar beet, soy, cotton and corn acreages in the U.S. are planted with GE varieties. It is estimated that 70-90% of GE crop biomass has been consumed by multiple generations of food-producing animals for the past 20 years. Numerous studies have shown compositional equivalence between GE and non-GE crops, and hundreds of peer-reviewed studies have shown no deleterious health effects associated with feeding GE crops to livestock. Additionally, the available USDA productivity trends and health metrics for the different livestock industries over the past 20 years do not show unexpected perturbations following the introduction of GE crops into the US feed supply. However, a few controversial and highly-publicized studies have claimed that consumption of GE feed resulted in deleterious health effects in a small number of animals. Despite being widely criticized for experimental design and other flaws, these outlier studies have been used to support views that there is a need to label meat, milk and eggs from animals that consume GE crops. Neither recombinant DNA (rDNA) nor protein from GE feed crops are reliably detected in the milk, meat and eggs from livestock that have been fed GE feed. Studies have shown that DNA from GE crops is chemically equivalent to DNA from non-GE crops and both are broken down the same way during digestion. The total amount of plant DNA remaining in animal feed is dependent upon many factors including how the feed is processed, and in feed from GE varieties rDNA makes up only a fraction of the total genomic DNA. As part of the natural digestive process, dietary DNA has been shown to move across the intestinal wall, but there is no evidence suggesting DNA or rDNA transfer from plants to animals. Since dietary DNA and protein cannot be reliably detected in animal products, and considering the wide trade and usage of GE feeds globally, managing separate supply chains to satisfy mandatory labeling requirements for products from animals that consumed GE feed would be complicated and expensive. There would be no food safety benefit from the substantial costs associated with segregating milk, meat and eggs from animals fed GE feed due to the fact that such products are both compositionally and analytically indistinguishable from those derived from animals fed non-GE crops.