BEIJING, China (AFP) — China’s demand for donkey skins to make a traditional medicine could wipe out more than half the world’s donkey population in the next five years, researchers said Thursday.

Nearly five million skins are used every year to make ejiao, a gel believed in China to be a remedy for troubles ranging from colds to ageing, putting enormous strain on donkey populations around the world, Britain-based animal welfare group Donkey Sanctuary said in a report.

Ejiao was once the preserve of emperors but is now highly sought after by a burgeoning middle class, with production growing 20 per cent each year between 2013 and 2016, Donkey Sanctuary said.

China’s domestic donkey population has collapsed by 76 per cent since 1992, and the country imports most of the donkey skins it uses, mainly from traders in South America, Africa and Asia.

There are currently around 45.8 million donkeys in the world, Donkey Sanctuary said.

The donkey skin trade has resulted in “suffering on an enormous and unacceptable scale”, the group’s chief executive Mike Baker said in a statement.

Researchers documented instances of unhygienic and inhumane processing conditions, including donkeys being crudely bludgeoned on the head at one slaughterhouse in Tanzania while still conscious and restrained.

At a holding facility in Brazil, malnourished animals were being kept in the same pens as “hundreds of donkey carcasses” that had contaminated the only available water source, “putting remaining donkeys at risk of either infectious disease or severe dehydration”.

Researchers warned the largely unregulated supply chain that has sprung up to meet rapidly expanding demand could put ejiao consumers in danger while contributing to the spread of disease.

Inadequate hygiene conditions increase the risk that “infected vectors, such as insects, may also be present on the product”, the report said.

Additionally, “donkeys owned by vulnerable communities along trade routes are at risk of being infected with diseases carried by donkeys ‘passing through”.

People living near donkey slaughterhouses in Kenya and Botswana have also reported exposed waste pits filled with donkey carcasses abandoned after their valuable skins were removed, contaminating local water supplies and attracting pests, the report added.

Pressure on suppliers has also caused an increase in donkey theft, threatening the livelihoods of the 500 million people in the world dependent on the animals for transporting goods and farm work, the researchers found.

A number of countries have begun to turn against the donkey skin trade.

Botswana, Senegal, Mali, Burkina Faso and Gambia all impose restrictions on it, while Zimbabwean authorities blocked a private donkey slaughterhouse under construction and Ethiopia closed its only functioning abattoir.

Donkey Sanctuary said China’s ejiao industry must move toward “more sustainable sources of raw materials,” including lab-grown donkey-derived collagen.