China has successfully cloned both Zhangmu cattle and Apeijiaza cattle, two endangered breeds found in southwest China's Xizang Autonomous Region, scientists announced Monday.

Four male calves of each breed were recently born in Yunyang County in southwest China's Chongqing Municipality, marking the world's first successful cloning of cattle from Xizang.

The Zhangmu and the Apeijiaza, two rare yellow cattle breeds native to the Qinghai-Xizang Plateau, are strategic resources for China, as these breeds can help researchers breed varieties well adapted to the harsh high-altitude environment.

According to the third national survey of livestock and poultry genetic resources conducted in 2021 and 2022, there were just 19 heads of Zhangmu cattle in Xizang's Shigatse City and 39 heads of Apeijiaza cattle in the autonomous region's Nyingchi City.

To urgently bring back these animals from the brink of extinction, China's Ministry of Agriculture and Rural Affairs dispatched a research team to Xizang in July 2022 to conduct body measurements and collect blood samples and ear tissue of the two types of cattle.

As there are currently no suitable conditions for cloning in Xizang, Yunyang County was chosen due to its climate and terrain resembling that of the cattle's native habitat and for its cattle breeding technology.

In the lab, Yu Dawei, a researcher from the Institute of Animal Sciences of the Chinese Academy of Agricultural Sciences, and his colleagues used somatic cell nuclear transfer technology to create cloned embryos.

Scientists started the transplant of the cloned embryos at a beef cattle breeding farm in Yunyang County in February 2023 and finally cracked the technological difficulties.

"The cloned embryos were transplanted into surrogate cows, and after a full-term pregnancy, we got eight cloned cattle," Yu said.

Two calves of each breed will be returned to Xizang this summer, while the remaining four will be raised to adulthood in Yunyang County and their semen will be collected and frozen for preservation.

The young animals born in low-altitude Chongqing will be moved gradually to Xizang to help them adapt to the high altitude there.

"Next, we will conduct transplant of cloned embryos of Zhangmu cattle and Apeijiaza cattle in Xizang, and combine the cloning technology with conventional breed-protection technologies to establish a sound system for the protection and utilization of genetic resources," Yu said.

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