Evaluation of compositional and nutritional equivalence of genetically modified rice to conventional rice using in situ and in vitro techniques

BACKGROUND: Concerns that genetically modified (GM) rice may pose nutritional risks have led to the need for studies comparing its nutritional composition with that of its isogenic counterpart. The present study explored the compositional and nutritional equivalence of rice grains and straw derived from a glufosinate herbicide-tolerant GM rice (Bar68), its non-transgenic conventional counterpart (D68) and a transgenic hybrid generation (X125S/Bar68) of Bar68 with conventional rice X125S. RESULTS: The chemical and nutritional composition, in vitro fermentation and in situ nylon bag degradation parameters were employed. Statistical comparisons to test the equivalence between D68, Bar68 and X125S/Bar68 were made with a criterion of maximum differences (scaled by D68) not exceeding 20%. The chemical and amino acid components of Bar68 and X125S/Bar68 were equivalent to those of D68, with the exception of Ca, P, K, Zn, cysteine and phenylalanine contents of grains and P and Mn contents of straw. Bar68 and X125S/Bar68 were equivalent to D68 in terms of in vitro fermentation and in situ degradation parameters of grains and straw, with the exception of the rapidly degradable component of neutral detergent fibre and the potentially degradable component of acid detergent fibre of straw. The maximum differences in some chemical components and nutritional indices were noted between D68 and X125S/Bar68. CONCLUSION: The results of this study indicated that grains and straw of the glufosinate herbicide-tolerant GM rice Bar68 and its transgenic hybrid generation X125S/Bar68 were essentially equivalent in chemical composition and nutritive value to those of its non-transgenic counterpart D68. (C) 2009 Society of Chemical Industry