As a billionaire and one of Wall Street’s biggest success stories, Carl Icahn has a significant influence on the American business world. He’s also controversial, as a friend and former special advisor to Donald Trump. But recently, Icahn has turned his attention to calling out corporations on their animal welfare standards.

In a public letter to McDonald’s shareholders published this month, the founder of Icahn Enterprises has accused the fast-food giant’s Board of Directors of not doing enough to reduce animal suffering in its supply chain.

The letter, which focuses on pig welfare and the overall issue of sustainability in business, follows a similar open letter sent to meat giant Kroger.

Both letters challenge the corporations’ use of pig gestation crates. According to the Humane League, the metal cages are so small that pregnant pigs are unable to turn themselves around.

Calling out corporations’ lack of animal welfare

In his letter, Icahn refers to McDonald’s 2012 pledge that it would source all of its pork from gestation crate-free suppliers within 10 years. The billionaire states that the fast-food giant has failed to meet that commitment.

McDonald’s has also recently claimed that by the end of this year, it “expects to source 85 percent to 90 percent of its US pork volumes from sows not housed in gestation crates during pregnancy.”

But Icahn claims to see through these statements.

He writes: “That assertion is a cynical fabrication intended to fool us into believing this egregious form of animal abuse in McDonald’s’ supply chain is largely not occurring.”

“In reality, these sows, who have multiple litters of piglets each year, are confined in gestation crates during each pregnancy for approximately four to six weeks, 24 hours a day, seven days a week,” he continues.

“They will spend these weeks immobilized in tiny crates, not much bigger than their bodies, where they can’t even turn around.”

Among other commitments, Icahn is demanding that McDonald’s eliminates gestation crates completely by the end of next year. He adds: “which it failed to do this year, despite having a decade to do so.”

In the scathing letter to Kroger’s CEO Rodney McMullen, Icahn took a similar tone. He wrote: “You’ve helmed a company that certainly has the gravitas to steer change, yet instead have condoned cruelty towards those who are the most defenseless.”