Digestive fate of transgenic DNA and protein in livestock tissues fed genetically modified feed ingredients: A review

The digestive fate of ingested transgenic DNA and/or proteins in livestock fed a diet containing genetically modified (GM) feed is at present the topic of scientific discussion. A number of studies have investigated the possible transfer and accumulation of novel DNA and/or proteins from transgenic plants in tissues samples of various livestock species, but the data reported are sometimes controversial. Therefore, this study aimed to evaluate the potential transfer and accumulation of transgenic DNA/ proteins from transgenic feed ingredients to livestock through reviewing scientific publications on experimental studies in large and small ruminants, monogastric and fish. Most of the studied experiments were conducted in Europe, and in majority these experiments, transgenic maize or soybean, or both, expressing insect resistant or herbicide tolerant or combination of both, were fed to the experimental animals. More than 50% of the experimental studies evaluated, reported the detection of transgenic DNA/protein from a number of analyzed samples of various livestock species. Transgene detection either in form of DNA or protein was more prevalence in the experimental studies when monogastric animals or fish were used as the experimental animals. Although, these transgenes were also detected in the tissues, organs and products of large and small ruminants, yet the detection frequency was less when compare with that in non-ruminants and fish. Thus overall, findings from this study indicated that transgenic DNA is not completely degraded during feed processing and digestion and that DNA fragments could be detected by well-established detection methods such as PCR or qPCR in a number of organs and tissues of livestock animals.