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Guertler P.,TU Munich | Guertler P.,Bavarian Health and Food Safety Authority | Paul V.,TU Munich | Paul V.,National Research Center on Yak | And 9 more authors.
Livestock Science | Year: 2010

The objective of this study was to investigate the fate of transgenic cry1Ab DNA and the encoded Cry1Ab protein during the metabolic degradation of dietary feed components in dairy cows and a potential transfer to blood,milk, feces or urine.A 25-month long-termfeeding trialwas conducted on thirty-six Simmentaler cows allocated in two groups fed diets containing either genetically modified corn (MON810, N=18) or the near-isogenic corn variety (N=18). The nutrients and energy contents of both maize varieties were comparable, ensuring equivalent feed conditions. Due to infertility or other production associated diseases, nine cows per group had to be culled and were replaced by heifers. Feed samples were collected weekly, whereas samples for feces, blood andmilkwere collectedmonthly, urine sampleswere taken bimonthly.All sampleswere analyzed for cry1Ab DNA by means of end-point PCR (feces, blood, urine) and quantitative real-time PCR (feed, milk). A sensitive and highly specific ELISA, optimized to quantify immunoreactive fragments of the Cry1Ab protein, was used to determine the recombinant protein in the collected samples. Non-transgenic feed sampleswere free of recombinant DNA and proteinwithin the limit of detection, while in transgenic feed samples both, a 206 bp fragment of cry1Ab and immunoreactive fragments of the Cry1Ab protein were present. In contrast, all blood, milk and urine sampleswere free of recombinantDNA and protein. The cry1Ab genewas not detected in any fecal sample, whereas immunoreactive fragments of the Cry1Ab protein were detected in feces from all cows fed transgenic feed.Milk of dairy cows fed genetically modified corn for 25months should be classified not different from milk of cows fed non-transgenic corn. © 2010 Elsevier B.V. All rights reserved.

Steinke K.,TU Munich | Guertler P.,TU Munich | Paul V.,TU Munich | Wiedemann S.,TU Munich | And 5 more authors.
Journal of Animal Physiology and Animal Nutrition | Year: 2010

A long-term study over 25 months was conducted to evaluate the effects of genetically modified corn on performance of lactating dairy cows. Thirty-six dairy cows were assigned to two feeding groups and fed with diets based on whole-crop silage, kernels and whole-crop cobs from Bt-corn (Bt-MON810) or its isogenic not genetically modified counterpart (CON) as main components. The study included two consecutive lactations. There were no differences in the chemical composition and estimated net energy content of Bt-MON810 and CON corn components and diets. CON feed samples were negative for the presence of Cry1Ab protein, while in Bt-MON810 feed samples the Cry1Ab protein was detected. Cows fed Bt-MON810 corn had a daily Cry1Ab protein intake of 6.0 mg in the first lactation and 6.1 mg in the second lactation of the trial. Dry matter intake (DMI) was 18.8 and 20.7 kg/cow per day in the first and the second lactation of the trial, with no treatment differences. Similarly, milk yield (23.8 and 29.0 kg/cow per day in the first and the second lactation of the trial) was not affected by dietary treatment. There were no consistent effects of feeding MON810 or its isogenic CON on milk composition or body condition. Thus, the present long-term study demonstrated the compositional and nutritional equivalence of Bt-MON810 and its isogenic CON. © 2010 Blackwell Verlag GmbH.

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