“A means of survival in Africa fuels the demand for luxury products from the middle class in China,” said Emmanuel Sarr, who heads the West Africa regional office of Brooke, a nongovernment organization based in London that works to protect donkeys and horses.

“This cannot continue.”

China is the main trading partner for many African countries. But in recent years its companies have been increasingly criticized for depleting the continent’s natural resources, from minerals to fish and now donkey skins, a censure once largely aimed at Western countries.

“This trade is undermining the mutual development talks between China and African countries,” said Lauren Johnston, an expert on China-Africa relations and an associate professor at the University of Sydney.

Some Chinese companies or local intermediaries buy and slaughter donkeys legally, but government officials have also dismantled clandestine slaughterhouses.

Rural communities in some African countries have also reported increasing cases of donkey theft, although there is no estimate of how widespread illegal trafficking has been.

Ethiopia is home to the largest population of donkeys in Africa, according to the Donkey Sanctuary, a British advocacy group. During a research trip there in 2017, Dr. Johnston said that many locals had shared their anger at China, “because they’re killing our donkeys,” she recounted.

China’s donkey skin trade is the key component of a multibillion-dollar industry for what the Chinese call ejiao, or donkey gelatin. It is a traditional medicine recognized by China’s health authorities, but whose actual benefits remain debated among doctors and researchers in China.

In recent years, what was once a luxury product became increasingly mainstream as incomes have risen among China’s middle and upper classes. Vendors of traditional Chinese medicine and health food companies have marketed ejiao (pronounced UH-jee-ow in Mandarin) as having potential benefits for people with circulatory, gynecological or respiratory issues.

Ejiao-based food products have flourished: pastries made with ejiao, walnuts, sesame and sugar have become a popular snack across China; a well-known brand of a tea beverage has targeted young consumers with ejiao milk tea.

China’s ejiao industry now consumes between four and six million donkey hides every year — about 10 percent of the world’s donkey population, according to Chinese news reports and estimates by the Donkey Sanctuary. China used to source ejiao from donkeys in China. But its own herd has plummeted from more than nine million in 2000 to just over 1.7 million in 2022.

So over the past decade China started turning to Africa, home to 60 percent of the world’s donkeys, according to the Food and Agriculture Organization of the United Nations.

Donkeys are highly resistant to harsh climate conditions and can carry heavy loads for a sustained period of time, making them a prized resource in some areas in Africa. Yet unlike other four-legged mammals, they are very slow to breed and efforts to raise donkey breeding to industrial levels, including in China, have shown limited success.

The decline in some countries has been sudden and sharp. Kenya’s donkey population declined by half from 2009 to 2019, according to research by Brooke. A third of Botswana’s donkeys have disappeared in recent years. Ethiopia, Burkina Faso and other countries have also seen their stocks decline at a high rate.

Beijing has been unusually quiet about the African Union’s ban on donkey hide exports, even though it has criticized other measures to stop the flow of goods into China, including restrictions recently imposed by the West on the export of semiconductor manufacturing equipment to China.

Neither China’s mission to the African Union nor its Ministry of Commerce responded to requests for comment.

Some African countries, like Ethiopia, Ivory Coast and Tanzania, have already implemented nationwide bans on donkey skin exports. But porous borders and lax implementation of fines have made it difficult to stem the trade.

For instance, in West Africa, donkeys are being trafficked from landlocked countries before they are slaughtered in often gruesome conditions in border areas with nations that have access to the sea. The pelts are then exported through cargo ports.

“Traffickers look for exit ways, like ports, which we must fight to keep closed,” said Vessaly Kallo, the head of veterinary services in the West African coastal country of Ivory Coast.

In some countries where donkey skins are legal, they also have been used to smuggle protected items like elephant ivory, rhino horns or pangolin scales that are wrapped in the skins, according to an investigation by the Donkey Sanctuary.

Governments have also faced pressure from farmers who raise donkeys and who reap a significant profit from the donkey skin trade. Botswana banned the export of donkey products in 2017, but backtracked a year later as a result of intense lobbying by farmers and instead set export quotas.

Pressure to limit the trade in donkey skins is mounting elsewhere. Since December, Amazon no longer sells donkey meat and other food supplements containing ejiao to customers in California to comply with that state’s animal welfare law.

U.S. Representative Don Beyer, a Democrat from Virginia, has repeatedly introduced a bill that would ban the production of ejiao and prohibit the sale and purchase of products with that ingredient.

In Africa, it is unclear yet how the continentwide ban might help save donkeys: African states now have to implement the ban through national legislation, a process that will take years. And national law enforcement agencies may not have the resources or will to tackle the illegal trafficking of donkey pelts.

Some African countries, like Eritrea and South Africa, had long been reluctant to embrace a ban, arguing that they had the right to decide how to use their natural resources, said Mwenda Mbaka, a leading animal welfare expert from Kenya, and a member of the African Union’s body for animal resources.

But he said the declining number of donkeys has reached a crisis level.

Last September, Mr. Mbaka took dozens of African diplomats on a two-day retreat in Kenya to raise awareness about animal mistreatment and the dangers that depleted donkey populations pose to rural households.