Abstract:A TaqMan real-time fluorescence polymerase chain reaction（PCR）assay was developed based on conserved single nucleotide polymorphism（SNP）locus of the fecundity booroola（FecB）gene in sheep.It provided a beneficial scientific reference for the authenticity detection of Xilingol mutton.The conserved SNP locus（A）of the FecB gene in Xilingol mutton（Uzhumuqin sheep and Sunite sheep）was significantly different from the corresponding gene locus（G）of breeds with high reproductive rates（small-tailed Han sheep and Hu sheep）.Germplasm resources of core conservation farms of Uzhumuqin sheep，Sunite sheep，and small-tailed Han sheep were collected for large-sample verification.The authenticity determination model of Xilingol mutton was established，and the applicability of the determination model was studied by cold storage sampling in the Spring Festival and on-site sampling during the slaughter season.The FecB genotypes AA，AG，and GG were determined according to the results of the real-time fluorescence amplification curve，and the ratio of gene locus（G）of more than 5% was taken as the judgment limit.The sample size of not less than 10 was set as the preconditions，so as to determine whether the Xilingol sheep contained breeds with high reproductive rates.During the Spring Festival，17 of the 20 batches of cold storage mutton samples were Xilingol mutton，and three batches of mutton samples included breeds with high reproductive rates.During the slaughter season，nine of the 11 batches of mutton samples were Xilingol mutton，and two batches of mutton samples included breeds with high reproductive rates.The established authenticity determination model of Xilingol mutton had a good ability to distinguish Xilingol mutton.There were breeds with high reproductive rates such as small-tailed Han sheep and Hu sheep in Xilingol local market.