Effects of long-term feeding with genetically modified Bt rice on the growth and reproductive performance in highly inbred Wuzhishan pigs

This study aimed to evaluate the safety of GM rice containing Cry1Ab protein (1.64 mg/kg) as the main ingredient in the diet after 360 days of feeding in the highly inbred Wuzhishan pigs (WZSP). A total of 28 pigs aged 3 months were divided into two groups and fed with either non-GM (MH86 group, female n = 7, male n = 7) or GM rice (Bt group, female n = 7, male n = 7). The total dosage of Cry1Ab protein for female and male pigs was 0.972 and 0.963 mg/kg body weight by the end of final weighing date (D 75), respectively. The results showed that there were no differences in the average daily gain, average daily food intake, body weight, feed conversion ratio, oestrus cycle duration, oestrus period, litter size, serum steroids, or the birth and weaning weight of offspring between Bt and MH86 groups. All pigs (n = 28) were sacrificed to collect tissues and blood samples for the analysis of relative organ weights, blood physiological and biochemical parameters and histopathological examinations. No significant differences existed in the tested indicators except that total protein was significantly higher in the MH86 compared to the Bt group (P < 0.05). In addition, the total bilirubin in the MH86 group was higher than the Bt group for females (P < 0.05), but no difference existed in males (P > 0.05). No pathologic abnormal changes were found from histopathological examinations of the main tissues. On the basis of these results, feeding with Bt rice for 360 days did not affect the growth, reproductive performance, hematology, or organ morphology in WZSP.