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Unintended Effects of Genetic Manipulation
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Inulin-storing potatoes had higher alkaloid content and pigs fed on them had reduced daily weight gain.

Manipulated Organism: Potato (Solanum tuberosum).

Inserted Transgenes and Intended Effect: Two genes for two enzymes, 1-SST and 1-FFT, from the globe artichoke (Cynara scolymus) to give potato plants the ability to synthesize and to store inulin as a carbohydrate rather than starch. The inulin content in the transgenic tubers was 50g/kg in the dry matter. "The tubers were intended to be used as a prebiotic functional food in human nutrition" (p. 20).

Goal of This Study: Investigate whether the transgenic potatoes showed, first, any other differences in substance composition and amounts from the unmanipulated parent variety and, second, whether pigs, as a model for humans, whose feed included these transgenic potatoes differed from pigs fed with the unmanipulated parent variety.

Results of This Study: There were no significant differences in mineral and amino acid content; starch content decreased in correlation with increase of inulin amounts, "indicating the storage capacity of carbohydrates was not affected by genetic modification" (p. 20). However, there were a number of nontarget effects:
  • Total alkaloid content of the transgenic potatoes was significantly higher (25%) than in the unmanipulated parent variety.
  • "Digestibility depressions of some nutrients . . . were detected and correspondingly lower energetic feeding value was measured" in pigs fed transgenic potatoes (p. 21).
  • Daily weight gain of pigs fed transgenic potatoes was lower (43 g per day).
  • Transgenic potatoes had lower silage production potential.

Additional Comments: The authors state that the "results confirm that substantial genetic modifications might be associated with altered concentrations of undesirable substances, and therefore increased attention should be paid to this fact [through] additional safety studies" (pp. 20-1).

Source: Flachowsky G., K. Aulrich, H. Böhme, and I. Halle (2007). "Studies on Feeds from Genetically Modified Plants (GMP) - Contributions to Nutritional and Safety Assessment," Animal Feed Science and Technology vol. 133, pp. 2-30.

Author Affiliations: Institute of Animal Nutrition, Federal Agricultural Research Center (FAL), Braunschweig, Germany; Institute of Organic Farming, FAL, Westerau, Germany.

Funding: Not mentioned.

Product Status: Not on the market as of 2008.

Copyright 2008 The Nature Institute.

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