Investigations on genetically modified maize (Bt-maize) in pig nutrition: fate of feed-ingested foreign DNA in pig bodies

Abstract

The passage and fate of ingested DNA in 48 pigs fed with diets containing (n=12) parental or (n=36) transgenic (Bt) maize were examined. Pigs were fattened from an initial live weight of 24 kg to approximately 108 kg. Animals fed transgenic maize were slaughtered in groups (n=6) 4, 8, 12, 24, 48 and 72 h after feeding the last maize-containing diet. Those slaughtered at up to 12 h received no further feed, while those held for longer prior to slaughter received a diet in which maize was replaced by barley and wheat. Control animals were slaughtered at 4 and 8 h. DNA extracted from tissues and gut contents was examined by PCR for the presence of plant DNA and for any transgenic material. Recombinant DNA was detectable in the intestinal contents up to 48 h after the last feeding of a diet containing the transgenic maize. PCR amplification of plant gene spacers produced fragments of different sizes, dependent on feed source. The feed source of rectum samples depended on individual passage rate in the groups and their restriction analysis showed grain species-specific patterns. Recombinant or maize-specific DNA was not detectable in tissue samples of pigs. In contrast, plant DNA fragments were detectable in the investigated pig tissues.