Abstract: [Objective] The aim of the present study was to clarify the infection status of Theileria in beef cattle in the Ninth Division of the Xinjiang Production and Construction Corps （hereinafter referred to as the Ninth Division）. [Method] A total of 118 blood samples were collected with anticoagulation tubes from beef cattle reared in the large-scale farms or scatter-feed households in the 161 （n=48）, 163 （n=22）, 164 （n=25） and 165 （n=23） Regiments of the Ninth Division, respectively. Among them, 48 samples were collected from the confined beef cattle and the remaining 70 samples were collected from the free-range beef cattle. The whole genomic DNA of the blood samples were extracted, and PCR assay was used to detect the presence of T. annulata, T. orientalis and T. sinensis with the specially designed primers. The species of Theileria were identified by sequence alignment, and the phylogenetic tree was constructed for genetic evolution analysis. The χ² test was employed to assess the differences in the infection rate of Theileria in beef cattle at different sampling sites and under different rearing modes. [Result] PCR detection showed that among the 118 blood DNA samples of beef cattle, 82 samples were positive for Theileria, with an overall infection rate of 69.49% （82/118）. All Theileria positive samples had T. orientalis alone, while T. annulata and T. sinensis were absent. The infection rates of Theileria in beef cattle in the 161, 163, 164 and 165 Regiments of the Ninth Division were 29.17% （14/48）, 95.45% （21/22）, 96.00% （24/25） and 100% （23/23）, respectively. There was an extremely significant difference in the infection rates of Theileria in beef cattle at different sampling sites （χ²=62.195, P<0.01）. A higher infection rate （97.14%, 68/70） of Theileria was observed in the free-range beef cattle, while a lower one （29.17%, 14/48） was observed in the confined beef cattle. The infection rates of Theileria in beef cattle under different rearing modes were extremely significantly different （χ²=62.061, P<0.01）. Among the 82 sequences obtained, 78 had 100% homology with the MPSP gene sequence of a T. orientalis isolate from cattle in Xinjiang Uygur Autonomous Region （GenBank accession number: ON462019）, and the sequence type was designated as TSE1. The remaining 4 sequences had 100% homology with the MPSP gene sequence of another T. orientalis strain of cattle origin in Xinjiang Uygur Autonomous Region （GenBank accession number: ON462018）, and the sequence type was designated as TSE2. The phylogenetic analysis demonstrated that the identified TSE1 and TSE2 sequences in present study were clustered with T. orientalis of cattle origin in Xinjiang Uygur Autonomous Region. [Conclusion] The species of Theileria prevailed in beef cattle in the Ninth Division of the Xinjiang Production and Construction Corps was T. orientalis. The free-range beef cattle had a higher infection rate of Theileria, suggesting the detection of Theileria in the free-range beef cattle herd should be strengthened.

Key words: beef cattle, Theileria, detection, identification