Xialing Zhao¹, Songyang Du², Qiang Zhang³, Quzhen Deji¹, Qipeng Lv⁴ and Wenqiang Tang^1*

Livestock in the northern areas of Xizang are increasingly affected by nematodes belonging to multiple families, resulting in an expanded geographic distribution of parasitic infections. We analyzed genetic classification status and evolutionary relationships of the ITS1 gene in free-range Tibetan sheep nematodes in the jurisdiction of Xizang. The gastrointestinal tract nematodes of free-range sheep were collected and the ITS1 gene fragment was amplified by PCR. The amplified products were subjected to agarose gel electrophoresis and sequenced. The results showed that 1-1, 1-2, 1-3, 3-1, 3-2, 3-3, 3-4 and 3-6 belong to the same branch as Marshallagia nematodes, whereas 1-2, 1-3, 1-4, 3-1 and 3-5 had the TTT sequence motif, indicating a distinct phylogenetic position distant from Marshallagia and Ostertagia nematodes while samples 3-7 clustered with Trichuris nematodes. These findings provide a reference basis for clarifying the typing of nematodes and the genetic evolution of pathogens in northern Xizang.

To Cite This Article: Zhao X, Du S, Zhang Q, Deji Q, Lv Q and Tang W, 2026. Genetic mapping of Marshallagia and Ostertagia nematodes isolated from free-range sheep in northern Xizang. Pak Vet J, 46(5): 1372-1375. http://dx.doi.org/10.29261/pakvetj/2026.124