Questions over reporting of GM feed studies
The researchers conducted "short-term (31 days), medium-term (110 days) and generational pig feeding studies where the health of piglets of sows fed Bt-maize is measured. No adverse effects were observed, suggesting that feeding Bt-maize to pigs of different ages is safe." The senior researcher is quoted as saying, "These findings can offer some assurance to consumers as to the safety of consuming Bt-maize."
But, as it happens, one of the studies – the short-term (31 day) one – has just been published independently in the current edition of the British Journal of Nutrition and it seems to tell a very different story. There the researchers note a number of differences in the pigs fed on Monsanto's Bt maize, including a lower feed conversion ratio and intestinal changes: "In conclusion, short-term feeding of Bt MON810 maize to weaned pigs resulted in increased feed consumption, less efficient conversion of feed to gain and a decrease in goblet cells/Î¼m of duodenal villus." (see the Abstract below)
The findings in this study are nowhere to be found in the reassuring press release put out to promote the findings of the 3 studies. We are told rather that "no adverse effects were observed" in any of the studies.
Effects of short-term feeding of Bt MON810 maize on growth performance, organ morphology and function in pigs
Metabolism and metabolic studies
British Journal of Nutrition, 14 February 2012, Volume 107, Issue 03: pp 364-371
Maria C. Walsha1, Stefan G. Buzoianua1a2, Gillian E. Gardinera2, Mary C. Reaa3, R. Paul Rossa3a4, Joseph P. Cassidya5 and Peadar G. Lawlora1 c1
a1 Teagasc, Pig Development Department, Animal and Grassland Research and Innovation Centre, Moorepark, Fermoy, County Cork, Republic of Ireland
a2 Department of Chemical and Life Sciences, Waterford Institute of Technology, Waterford, Republic of Ireland
a3 Teagasc, Food Research Centre, Moorepark, Fermoy, County Cork, Republic of Ireland
a4 Alimentary Pharmabiotic Centre, University College Cork, Cork, Republic of Ireland
a5 Veterinary Sciences Centre, University College Dublin, Belfield, Dublin, Republic of Ireland
Male weanling pigs (n 32) with a mean initial body weight of 7·5 kg and a mean weaning age of 28 d were used in a 31 d study to investigate the effects of feeding GM (Bt MON810) maize on growth performance, intestinal histology and organ weight and function. At weaning, the pigs were fed a non-GM starter diet during a 6 d acclimatisation period. The pigs were then blocked by weight and litter ancestry and assigned to diets containing 38·9 % GM (Bt MON810) or non-GM isogenic parent line maize for 31 d. Body weight and feed disappearance were recorded on a weekly basis (n 16/treatment), and the pigs (n 10/treatment) were killed on day 31 for the collection of organ, tissue and blood samples. GM maize-fed pigs consumed more feed than the control pigs during the 31 d study (P < 0·05) and were less efficient at converting feed to gain during days 14 30 (P < 0·01). The kidneys of the pigs fed GM maize tended to be heavier than those of control pigs (P = 0·06); however, no histopathological changes or alterations in blood biochemistry were evident. Small intestinal morphology was not different between treatments. However, duodenal villi of GM maize-fed pigs tended to have fewer goblet cells/Î¼m of villus compared with control pigs (P = 0·10). In conclusion, short-term feeding of Bt MON810 maize to weaned pigs resulted in increased feed consumption, less efficient conversion of feed to gain and a decrease in goblet cells/Î¼m of duodenal villus. There was also a tendency for an increase in kidney weight, but this was not associated with changes in histopathology or blood biochemistry. The biological significance of these findings is currently being clarified in long-term exposure studies in pigs.
(Received February 04 2011)
(Revised April 13 2011)
(Accepted April 28 2011)
(Online publication July 01 2011)