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The inclusion of genetically modified (GM) plants in animal feed and for human consumption has increased consistently over the past 15 years. Since the introduction of GM crops, much debate has centered on issues related to safety for consumption. Bt MON810 maize is engineered to express the truncated Cry1Ab toxin from Bacillus thuringiensis, which confers resistance to the European maize borer. This toxin interacts with the target larvae’s intestinal cells disrupting the intestinal lining leading to death. However, the toxin is believed to be non-toxic to mammals, birds, reptiles and amphibians due to a lack of specific receptors in the intestinal tract. In the present study, we evaluated in pigs the effects of 31 d of feeding Bt MON810 maize compared with an isogenic parent line maize. Particular attention was afforded to changes in growth performance, intestinal morphology and organ pathology and function in an attempt to identify any changes that may serve as an early warning sign for a biological effect. For this purpose, 32 male weanling pigs with a mean initial body weight of 7.5 kg and a mean weaning age of 28 d were used. At weaning, the pigs were fed a non-GM starter diet during a 6 d acclimatization 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/mm of villus compared with control pigs (P = 0.10). The biological significance of these findings is currently being clarified in long-term exposure studies in pigs.
MC Walsh, SG Buzoianu, GE Gardiner, MC Rea, RP Ross, JP Cassidy and PG Lawlor. Effects of short-term feeding of Bt MON810 maize on growth performance, organ morphology and function in pigs. 2012. British Journal of Nutrition, 107: 364-371.