An undercover video produced by animal rights group Mercy for Animals is taking aim at Burger King’s record.

The graphic footage shows employees at an Idaho dairy farm kicking a cow in the face as blood drips from its nose and a tractor dragging a downed cow by a rope around its neck across a filthy floor. Another employee jumps on a cow like a trampoline and curses as he slams the cow’s neck in a metal gate. The animals are kept in tiny pens and limp on broken legs.

Bettencourt Dairies, with 60,000 cows, is the largest dairy farm in Idaho and supplies milk to Schreiber Foods, one of the companies whose cheese ends up on Burger King’s Whoppers. Mercy for Animals director Nathan Runkle accuses the Miami-Dade-based fast-food chain of allowing a “culture of cruelty” at its supplier farms.

“The secret ingredient in Burger King’s cheese is horrific animal abuse,” Runkle said. “No socially responsible corporation should support dairy operations that beat, kick, mutilate, confine and neglect animals.”

A statement from Burger King defended the company’s commitment to animal rights with all vendors, and promised swift action in response to documented abuse at the dairy farm, which supplies a small percentage of dairy products to the chain. Burger King has recently won progress awards from PETA and the Humane Society for its code of ethics on animal welfare.

Matt Prescott, food policy director at the Humane Society of the United States, called the abuse in the video “reprehensible,” but supported Burger King’s record on animal rights over the past decade. He said the company “is doing more to improve farm animal welfare than any other major restaurant chain.”

Burger King was the first fast-food company in the country to use only cage-free eggs and eliminate cruel pig gestation crates from its pork supply chain, Prescott said.

There are no federal guidelines for animal treatment on dairy farms, and Mercy for Animals is calling on Burger King to set a higher standard for its suppliers.

Five Bettencourt employees were fired, three of whom face criminal charges for violations of Idaho code on animal cruelty. One of those workers has been arrested; the other two are still at large.

Bettencourt Dairies employs more than 500 people, and CFO Rick Onaindia said the abuse that was recorded in July was an isolated incident. The company, one of at least seven to supply milk to Burger King cheese producers, has shown the video to all workers and changed training protocol to reflect a “zero tolerance” attitude toward animal cruelty.