Effects Of Diets With Bt Rice On The Growth And Reproductive Performance And Gastrointestinal Health In Wuzhishan Pigs

In order to evaluate the safety of transgenic Bt rice containing Cry1Ab protein(1.64 mg/kg)as the main energy source feed and establish a human food safety assessment model,Bt rice was fed for 360 and 420 days in the high inbred strain of Wuzhishan pig for two generations,respectively.Based on feeding genetically modified(GM)rice or non-genetically modified(Non-GM)rice,a total of 28 three-month-old Wuzhishan pigs in the first generation(f0 generation)were divided into GM group(fDZM group:n=7;fDZG group:n=7)and Non-GM group(fDFM group:n=7,f0ZM group:n=7).Totally 27 Wuzhishan pigs in the second generation(fl generation)were divided into GM group(flZM group,n=11;flZG group,n=6)and Non-GM group(f1FM group,n=5;f1FG group,n=5).In the f0 generation,to the end of body weight gain measurement(D 75),the average CrylAb protein doses obtained in fDZM and f0ZG groups were 0.972 and 0.963 mg/kg BW,respectively.In the fl generation,until the end of body weight gain measurement(week 10),the average CrylAb protein doses obtained in f1ZM and f1ZG group were 1.003 and 1.234 mg/kg BW,respectively.The two generations of Wuzhishan pigs were slaughtered at the end of the experiment,and blood and tissue samples were collected to further examine the blood and serum biochemical indicators,the ratio of the organs to the body,and the histopathological examination.The results of the fO feeding trial showed that GM group compared with the Non-GM group,there were no significant differences in the body weight gain(ADG),daily intake(ADFI),body weight(BW),feed conversion rate(FCR),estrus cycle interval,and estrus during the duration,litter size,piglet birth and weaning weight,and serum sex steroid hormone levels,but the serum total protein content in the GM group was lower than that in the Non-GM group(P<0.05).In addition,serum total bilirubin level in the f0ZM group was lower than those in the fDFM group(P<0.05),and there was no significant difference between the male pigs.The results of fl generation feeding showed that there was a significant difference in ADG and FCR from week l to week 10 in female pigs of f1ZM and f1FM groups at weeks 3 and in f1ZG and f1FG groups,and the body weight of f1ZG group in week 2 was significantly lower than the f1FG group(P<0.05),no other differences were found.The alanine aminotransferase(ALT)between the f1ZM and f1FM groups and the alkaline phosphatase(ALP)between the flZG group and the f1FG group were different,but no abnormal histopathological observations were observed.To assess the effects of transgenic Bt rice on gastrointestinal health,the fecal samples were collected from 26 Wuzhishan pigs of the f0 generation(Female:f0FM group,n=7,f0ZM group,n=6;Male:f0FG group,n=7,fDZG group,n=6)and 27 Wuzhishan pigs of the fl generation(Female:f1FM group,n=5,f1ZM group,n=11;Male:f1FG group,n=5,f1ZG group,n=6).The results of high-throughput sequencing of 16S rRNA showed that there were some significant differences in the components of the gut microbiota between the GM and Non-GM groups.The relative abundances of the Trichophyton and Proteobacteria between the f1F and f1Z groups(5.1%vs 3.2%,P = 0.05 and 1.3%vs 1.9%,respectively,P = 0.06)tended to be significantly different.In addition,there was a significant difference in the relative abundance of Enterobacteriaceae between the f1F and f1Z groups(0.1%vs 0.6%,P = 0.01).At the genus level,the relative abundances of CF231 and SMB53 in the f0Z group(0.8%vs 0.3%and 0.4%vs 0.2%,respectively,P<0.01)were significantly higher than those in the fDF group.The relative abundance of the Escherichia in the f1F and f1Z groups(0.1%vs 0.5%,P = 0.01)was significantly different.The results of the cluster distribution obtained from the OTU classification with a threshold of 97%showed no significant difference.No abnormal pathological changes occur in the gastrointestinal tissues.In summary,long-term intake of transgenic Bt rice carrying high levels of CrylAb exerts no unintended adverse effects on Wuzhishan pigs.Although,the uptake of Bt rice it caused changes in the composition and structure of the intestinal microflora,it had no adverse effects on intestinal health and organ function.These results indicate that the Wuzhishan pig is well tolerant to the intake of Bt rice and Bt rice containing Cry1Ab protein is comparable to non-transgenic rice in terms of nutrition and safety.