Analysis of stable carbon and nitrogen isotope compositions and geographical origins of sheep tissues.

【Objective】 The carbon and nitrogen isotope compositions of sheep tissues were investigated, and their variations among the regions were discussed, the aim is to provide the scientific basis for using stable isotope analysis to trace the geographical origin of mutton; 【Method】 The δ13C and δ15N values of sheep muscle, hair and their feeds originating from three pastoral areas including Alxa League, Xilin Gol League and Hulunbuir City of Inner Mongolia, and two agricultural areas including Chongqing City and Heze City were determined by Isotope Ratio Mass Spectrometry(IRMS). The differences of carbon and nitrogen compositions in sheep tissues from above regions were compared, and the correlations of isotope compositions between different tissues were analyzed. Moreover, the change of δ13C and δ15N values in sheep tissues under different feeding modes and environmental conditions were also investigated; 【Result】 C and N isotope ratios of sheep tissues from different regions showed significant differences; the δ13C values of tissues were highly correlated with the δ13C value of their feeds, mainly affected by the kinds of forage; the δ15N values were related with feeds and geographical origin. In addition, the δ13C and δ15N values between defatted muscle, crude fat and sheep hair were both significantly correlated. 【Conclusion】 The stable carbon and nitrogen isotopes could be used as reference indexes for tracing geographical origin and feeding practice of sheep. The defatted muscle, crude fat, and sheep hair could be used in mutton geographical origin assessment.