BUENOS AIRES — Argentina is best known for its beef. But, unbeknownst to many, it also has a long tradition of killing horses for meat.

The fact is especially surprising given that within the South American country, consumption of carne de caballo is an absolute no-no. There are some eager markets abroad, however, and Argentine producers are more than willing to meet that demand. In fact, Argentina is the world's leading horse meat exporter.

The networks in this bloody, hidden trade supply approximately 60% of the horse meat consumed in Europe. That amounts to about 200,000 horses per year. But where exactly do these animals come from? And why is this trade so secret?

The makers of a new documentary called Cinco Corazones ("Five Hearts') try to answer these questions and more. They also hope the film will create pressure to bring an immediate end to the industry.

The documentary follows a three-year investigation into this cruel process, and is presented by the actress and animal rights activist Liz Solari. It reveals the mistreatment of animals from the start to the end of their lives. It also highlights the efforts of several NGOs in Argentina, namely the Franz Weber Foundation, Tierschutzbund Zürich (TSB) and the Animal Welfare Foundation (AWF) to prevent this trade.

It's crucial for European consumers to know what's behind the food placed on their plates every day.

Part of the problem, they argue, is that there's no official register of horse farms destined for meat production. This is thought to lead to traditional or sporting practices or acts of corruption inside a business that essentially relies on cruelty to animals.

The horses themselves aren't necessarily raised for their meat. They're retired work horses (something that's still common in rural areas) or former polo horses that are then handed over for meat production at the end of their useful lives.

"It is important for Argentines to know what exactly happens with the horse that is so representative of our cultural DNA," Martín Parlato, director of Cinco Corazones and founder of the Posibl. production company, told Clarín. "But it's also crucial for European consumers to know what there is behind the food placed on their plates every day."

Horses are often associated with freedom and nobility. "But the documentary shows that the one thing Argentine horses lack is freedom," says Parlato.

The film shows revealing images of what it terms the "horror camps of Ezeiza," and focuses on the theft and killing of horses, and the complicity on the part of local authorities. It also touches on the cruel business of bleeding mares, which Parlato describes as the most troubling thing he came across in his research.

"It's the height of abuse," he says. "It's a big business and part of a vicious circle in which mares are impregnated but then made to abort in order to extract up to 10 liters of blood."

That blood contains a hormone that is then exported for use on pig farms, where it helps in the insemination process. "Thousands of mares are forced every year to experience this situation on multiple occasions and once their bodies can no longer resist, they are sent for killing and refrigeration before being exported to European countries as gourmet meat," Parlato explains.

The NGOs featured in the program have filed a court action against one firm in particular, Syntex SA., which is based in the Buenos Aires province.

Why should killing horses be immediately banned? For ethical reasons, says Alejandra García, head of the Franz Weber Foundation in Argentina and the Equidad horse sanctuary.

There is "nothing good" happening inside horse abattoirs, she says. "And the industry knows it," García adds. "That's why it's so difficult to gain entry to see and film the entire process, from the moment the horse arrives in the cold room until it enters the chamber where, hanging by a leg and still conscious, it has its throat slit."

To abolish this cruel practice, sensitivity will need to be coupled with courage.

She says another reason to crack down is the tremendous informality of this business, which feeds on stolen horses and adds "an enormous security problem for those of us living with horses." Banning this deadly business would thus bring more economic relief than losses.

"It would enhance security in rural zones where livestock theft is an everyday occurrence, without causing economic harm to the country," García says.

Is the government interested in such a ban? Parlato says that for now, the answer is unclear. "We do know that inside the government there are officials and politicians who are sensitive to the suffering of animals," he says. But to abolish this cruel practice, he adds, that sensitivity will need to be coupled with "courage" on the legislative front.

The industry is thought to have a turnover of some $60 million a year. Comparatively speaking, horse meat is not one of the country's big export earners, says García. The country has four refrigeration facilities managed by Senasa, the country's food safety agency. The rest is done in a clandestine manner, with horses sent by gatherers across the country.

Such gathering facilities effectively "launder" stolen horses before introducing them into this production circuit. Once stolen, they are practically never recovered, the documentary explains. And the absence of official figures does nothing to save their lives.