The research (INRA-Versailles) supervised by Yves Bertheau, is published in the Journal of Agricultural and Food Chemistry amidst ongoing debate about the traceability and labelling of foods containing GMOs.
According to the researchers, “small pieces of DNA from food may permeate the intestinal membrane and enter the ruminant's bloodstream”. But “no traces of the transgenic DNA sequence of Bt176 maize has been found in samples” of the bovine blood tested.
As a consequence, the researchers declared that “there are currently no analytical controls available which can detect if an animal has been GMO-fed”.
The authors of the study analysed blood samples taken on two groups of cows, the first fed with transgenic Bt176 maize which synthesizes insecticidal protein, the second not.
They confirmed that DNA from the food eaten by the ruminants could enter the bloodstream via the intestinal walls, but they were unable to find the Bt176 fragment.
“This DNA fragment could theoretically permeate the intestinal membrane just like any other genome fragment,” considered the researchers, “but its concentration in the samples is so slight that current techniques could not detect it.”
The study was undertaken at the request of the dairy industry in order to know if testing could identify which animals had been GMO-fed. This would have been a way for the dairy industry to promote conventionally fed animals.
For the moment, INRA underlines that “no legislation in the world has considered these claims”. In Europe, products (milk, eggs, etc) derived from animals fed with GM feed are not subjected to labelling regulations, contrary to products derived from GMOs.