Determining whether or endogenous plant DNA is detectable in dairy milk or beef organs

The fate of transgenic DNA in products derived from farm animals fed genetically modified feed was assessed. Sensitive methods were developed to analyze milk for the presence of transgenic and plant DNA from cows fed a diet containing conventional or transgenic cottonseed or maize. Genomic DNA was extracted from milk and analyzed by PCR followed by Southern blot for frag' ments of the crylAc transgene and an endogenous cotton gene, acp1, from cows fed a diet containing whole cottonseed. Additionally, milk, liver, kidney, and spleen were assessed for fragments of the crylAb transgene and an endogenous maize gene, sh2, from animals fed a diet containing maize grain. No sample was positive for transgenic or plant DNA fragments at the limits of detection for the assays following detailed data evaluation criteria. Results for sh2 analyses of milk were, however, indeterminate. A fragment of a bovine gene, prl, was amplified from each DNA extract to show that all preparations were amenable to PCR. These results indicate that DNA, whether derived from conventional or transgenic feed, is not present at detectable levels in bovine milk or organs. Abbreviations: acpl = gene encoding cotton acyl carrier protein; BG = Bollgard cotton; BGII = Bollgard II cotton; Bt = Bacillus thuringiensis; cp4 epsps = coding region for the CP4 EPSPS protein; CP4 EPSPS, synthetic enzyme 5-enolpyruvylshikimate-3-phosphate synthase derived from Agrobacterium sp. strain CP4; crylAb = coding region for the Bt CrylAb protein; CrylAb = insecticidal protein from Bt; crylAc = coding region for the Bt CrylAc protein; CrylAc = insecticidal protein from Bt; LOD, limit of detection; PCR, polymerase chain reaction; prl = gene encoding bovine prolactin; RR = Roundup Ready; sh2 = gene encoding maize ADP glucose pyrophosphorylase; YG = YieldGard Corn Borer maize.