Safety Assessment Of Transgenic Rice Used In Broiler Diet

Five experiments were employed to evaluate safety of the brown rice derived from transgenic rice with crylAb gene used as a feed ingredient in the broiler diet. Effect of transgenic brown rice on the performance, muscle composition, digestibility, serum parameters, organ development, immune response and intestinal microflora of broilers were studied and crylAb gene and CrylAb protein were detected in blood, muscle and organs of broilers. The results showed that the transgenic brown rice had no safety problems used in the broiler diet.Experiment 1. Effect of Transgenic Rice on Performance and Muscle Composition of BroilersThis experiment was composed of 2 trials. In trial 1, the nutrient composition of the brown rice was analysed. It showed that the content of crude protein of transgenic brown rice was lower than the nontransgenic parent rice. In trial 2, a 42-d feeding study was used to evaluat whether a broiler diet prepared with brown rice derived from transgenic rice Btl10 (Bt group) had any unanticipated adverse effects on male or female broiler chickens as compared with diet prepared with brown rice derived from nontransgenic control rice Xiushuil10(Xs group). In the period of 8 to 21 d, no significant differences in body weight gain and average feed intake of the male and female broiler chickens were observed between birds reared on the diets prepared with transgenic rice or control rice (P>0.05), but feed conversion ratio (feed/gain) of the male broiler chickens fed diet prepared with transgenic rice was better than that of the broiler chicken fed diet prepared with nontransgenic rice. In the period of 22 to 42 d, all performance parameters of the Bt group were better than that of Xs group, but the feed conversion ratio of female broiler was not observed statistically significant difference (P>0.05). Carcass characteristics and muscle composition were similar between birds reared on the two types of diets. Near infrared spectroscopy analysis for breast muscle of broilers showed that the spectroscopy of muscle had no difference, but principal component analysis of their data showed that the muscle had been separated into two parts. Although it is not clear whether this enhanced performance and difference of muscle PCA were attributable to the transgenic rice, or due to possible slight differences in overall composition of the formula diet, it was clear that the transgenic rice had no observed deleterious effect to birds in this trail.Experiment 2. Effect of Transgenic Rice on Digestibility, Serum Parameters and Organ Development of Broilers.Ninety-six day old broilers were divided into two groups randomly. One group was fed a diet containing transgenic brown rice and the other group was fed a diet containing corresponding nontransgenic brown rice. Digestibility of crude protein, amino acids, calcium, phosphorus and metabolizable energy in the diet of the 18～21 and 39~42 day of age were determined, some serum parameters were measured, the post-mortem organ index was calculated and organ analysis were performed at the end of the experiment. The results showed that no significant difference were observed(P>0.05) in the digestibility of crude protein, amino acid, calcium, phosphorus and the metabolizable energy of the diet in two phases between the two groups. The serum parameters and organ index were not significantly different (P>0.05). No histopathological damages were detected. From this trial, it was concluded that there were no observed adverse effects of the transgenic brown rice on the broiler chicken's health.Experiment 3. Effect of Transgenic Brown Rice on Immune Organ Development and Immune Response of BroilersA 42 days feeding study evaluated whether the transgenic rice used in broiler's diet had any deleterious effect on development of immune organs and immune response of broilers. Ninety-six day old broilers were divided into two experimental groups randomly. One group was fed the diet prepared from transgenic brown rice and the other group was fed the diet prepared from corresponding nontransgenic brown rice. Immune organ index, lysozyme content and anti-NDV antibody of the 21 day and 42 day of age in broilers were determined, and serum globulin content and peripheral blood T lymphocyte cell proliferation of 42 day of age of broilers were measured. The results showed that no statistically significant difference were observed (PX).O5) in the immune organ index and immune response between two groups. From results of this trial, it was concluded that there were no observed adverse effects of the transgenic brown rice on the broiler chicken's immune organ development and immune response.Experiment 4. Effect of Transgenic Rice on Intestinal Microbial Community in BroilersEffect of transgenic rice on intestinal microbial community in broilers was studied by traditional method and denaturing gradient gel electrophoresis (DGGE) analysis of 16S ribosomal RNA. Ninety-six day old broilers were allocated randomly into two groups, fed diet prepared from transgenic rice (Bt group) or prepared from nontransgenic rice (Xs group) separately. The traditional method results showed that the microbial community of total aerobic bacteric, anaerobic bacteria, Lactobacillw and E. colibacillus were no significant difference in cecum (.P>0.05), but the total anaerobic bacteria and Lactobacillus were significantly higher (PO.05) in ileum in Bt group broiler than that of Xs group. DGGE analysis showed there were no abnormity of the microflora in the cecum and ileum. In conclusion, transgenic rice had no observed adverse effect on the intestinal microbial community in broilers.Experiment 5. Detection of Recombinant DNA Fragment and CrylAb Protein of Transgenic Rice in BroilersWith the development of biotechnology, more and more genetically modified plants were used in feed. People showed great attention on the fate of the recombinant DNA and the protein expressed by recombinant DNA of genetically modified plants in animals. In this study, 8 broilers of 42 day old reared on diet prepared from transgenic brown rice were selected. The blood, organs and muscle were collected under sterile condition. PCR and ELISA methods were used to detecte the 559 bp fragment ofcrylAb gene and CrylAb protein in these samples. The results showed that no 559 bp fragment of crylAb gene and CrylAb protein were detected in blood, organs and muscle. Therefore, there were no residua of transgenic composition in broilers.In conclusion, no adverse effect was found when the transgenic rice was used in broiler diet in this series of experiments. So it is safe in the period of the broiler growth that the transgenic rice was used in broiler diet, but the long time effect needs to be further investigated. These studies will not only facilitate safety assessment of transgenic plant used in feed, but also provide reference scientific data for the transgenic rice used in food.