Wednesday, August 7, 2013 - At a commercial piggery in the US, 168 just-weaned pigs were split into two groups: One group was fed a typical soy and corn diet and the other group received a diet composed of widely-used varieties of GM soy and GM corn. Both groups were slaughtered after about 23 weeks. Blood samples for standard biochemistry tests were taken before slaughter and autopsies were done by qualified veterinarians who didn’t know if a given pig was fed the GM diet or not, so their observations were completely unbiased.
The GM diet contained three GM genes and therefore three GM proteins. One protein made the plant resistant to a herbicide, and two proteins were insecticides. Pigs were chosen as test animals because they have a similar digestive system to humans, and because some of the investigators had been observing reproductive and digestive problems in swine-fed GM crops.
On average, the weight of the uterus of pigs fed the GM diet, as a proportion of the weight of the pig, was 25% higher than the control pigs. This is biologically significant finding was also statistically significant.
The level of severe inflammation in stomachs was markedly higher in pigs fed the GM diet. Pigs on the GM diet were 2.6 times more likely to get severe stomach inflammation than control pigs. Males were more strongly affected. While female pigs were 2.2 times more likely to get severe stomach inflammation when on the GM diet, males were 4 times more likely. These findings are both biologically significant and statistically significant.
It was found that that these key findings were not reflected in the standard biochemistry tests that are done in GM feeding studies, probably because standard biochemistry tests provide a poor measure of inflammation and matters associated with uterus size. However, a marginally significant change on a measure of liver health in the blood of GM-fed pigs was found.