Photo taken on Oct. 11, 2021 shows a South China tiger at the Shanghai Zoo in east China's Shanghai. The South China tiger is a rare kind endemic to China and is on the national first-class protection list. Currently, a total of 28 South China tigers are living in the Shanghai Zoo. The zoo has recorded each tiger's information and established a gene bank for research, and tigers are treated and bred in a scientific way. (Photo: Xinhua)

Photo taken on Oct. 11, 2021 shows a South China tiger at the Shanghai Zoo in east China's Shanghai. The South China tiger is a rare kind endemic to China and is on the national first-class protection list. Currently, a total of 28 South China tigers are living in the Shanghai Zoo. The zoo has recorded each tiger's information and established a gene bank for research, and tigers are treated and bred in a scientific way. (Photo: Xinhua)

A breeder feeds a South China tiger at the Shanghai Zoo in east China's Shanghai, Oct. 11, 2021. The South China tiger is a rare kind endemic to China and is on the national first-class protection list. Currently, a total of 28 South China tigers are living in the Shanghai Zoo. The zoo has recorded each tiger's information and established a gene bank for research, and tigers are treated and bred in a scientific way. (Photo: Xinhua)

A researcher introduces South China tigers through a studbook at the Shanghai Zoo in east China's Shanghai, Oct. 11, 2021. The South China tiger is a rare kind endemic to China and is on the national first-class protection list. Currently, a total of 28 South China tigers are living in the Shanghai Zoo. The zoo has recorded each tiger's information and established a gene bank for research, and tigers are treated and bred in a scientific way. (Photo: Xinhua)

Photo taken on Oct. 11, 2021 shows a South China tiger at the Shanghai Zoo in east China's Shanghai. The South China tiger is a rare kind endemic to China and is on the national first-class protection list. Currently, a total of 28 South China tigers are living in the Shanghai Zoo. The zoo has recorded each tiger's information and established a gene bank for research, and tigers are treated and bred in a scientific way. (Photo: Xinhua)

A researcher shows gene samples of South China tigers at the Shanghai Zoo in east China's Shanghai, Oct. 11, 2021. The South China tiger is a rare kind endemic to China and is on the national first-class protection list. Currently, a total of 28 South China tigers are living in the Shanghai Zoo. The zoo has recorded each tiger's information and established a gene bank for research, and tigers are treated and bred in a scientific way. (Photo: Xinhua)

Photo taken on Oct. 11, 2021 shows a South China tiger at the Shanghai Zoo in east China's Shanghai. The South China tiger is a rare kind endemic to China and is on the national first-class protection list. Currently, a total of 28 South China tigers are living in the Shanghai Zoo. The zoo has recorded each tiger's information and established a gene bank for research, and tigers are treated and bred in a scientific way. (Photo: Xinhua)

Photo taken on Oct. 11, 2021 shows a South China tiger at the Shanghai Zoo in east China's Shanghai. The South China tiger is a rare kind endemic to China and is on the national first-class protection list. Currently, a total of 28 South China tigers are living in the Shanghai Zoo. The zoo has recorded each tiger's information and established a gene bank for research, and tigers are treated and bred in a scientific way. (Photo: Xinhua)

Photo taken on Oct. 11, 2021 shows a South China tiger at the Shanghai Zoo in east China's Shanghai. The South China tiger is a rare kind endemic to China and is on the national first-class protection list. Currently, a total of 28 South China tigers are living in the Shanghai Zoo. The zoo has recorded each tiger's information and established a gene bank for research, and tigers are treated and bred in a scientific way. (Photo: Xinhua)

Photo taken on Oct. 11, 2021 shows a South China tiger at the Shanghai Zoo in east China's Shanghai. The South China tiger is a rare kind endemic to China and is on the national first-class protection list. Currently, a total of 28 South China tigers are living in the Shanghai Zoo. The zoo has recorded each tiger's information and established a gene bank for research, and tigers are treated and bred in a scientific way. (Photo: Xinhua)

A researcher shows a gene sample of a South China tiger at the Shanghai Zoo in east China's Shanghai, Oct. 11, 2021. The South China tiger is a rare kind endemic to China and is on the national first-class protection list. Currently, a total of 28 South China tigers are living in the Shanghai Zoo. The zoo has recorded each tiger's information and established a gene bank for research, and tigers are treated and bred in a scientific way. (Photo: Xinhua)

A breeder adds vitamin pills into South China tigers' food at the Shanghai Zoo in east China's Shanghai, Oct. 11, 2021. The South China tiger is a rare kind endemic to China and is on the national first-class protection list. Currently, a total of 28 South China tigers are living in the Shanghai Zoo. The zoo has recorded each tiger's information and established a gene bank for research, and tigers are treated and bred in a scientific way. (Photo: Xinhua)