Carl Icahn is broadening a push to get McDonald's Corp to improve suppliers' treatment of pigs raised for bacon and sausage, reported Reuters.

The billionaire activist investor, who has described himself as an animal lover, on Thursday called on the burger chain to make a global pledge to eliminate the use of metal enclosures to house pregnant pigs. He has said the enclosures, known as gestation crates, are "obscene" and cause pigs unnecessary pain.

McDonald's last month said it would remove gestation crates from its US supply chain by 2024, pushing back a 10-year goal it set in 2012 with Icahn's urging.

Pork producers use the crates, which are about 7 feet (2.1 m) long and 2 feet wide, to confine mother pigs with no room to turn around.

Icahn said he also wants McDonald's to commit to buying pork from suppliers that abide by standards set in a California animal-welfare law, Proposition 12. Approved by California voters in November 2018, the measure prohibits confining a breeding pig with less than 24 square feet of usable floor space.

McDonald's had no immediate comment on Icahn's call for a global commitment or on his demand that the company buy only from suppliers that comply with Proposition 12.

Icahn nominated two members to McDonald's board of directors in an escalating fight over the treatment of pigs by suppliers.

"Perhaps if McDonald's leaders applied the same efforts they do towards obtaining better compensation packages for themselves to getting their suppliers to become completely gestation crate free, we wouldn't be having this proxy fight," Icahn said.

Icahn and his daughter, Michelle Icahn Nevin, have said McDonald's claims are misleading because the company allows producers to keep pregnant pigs in gestation crates for the first four to six weeks of their 16-week pregnancies.

Asked to comment, McDonald's said it has not backtracked on its 2012 pledge. The company said last month that a move to "crate-free" pork is impossible with the current US pork supply and would be "a departure from the veterinary science used for large-scale production."

McDonald's said it expects to buy 85% to 90% of its USpork from sows, or mother pigs, not housed in gestation crates during pregnancy by the end of 2022.

Ten years ago, the Humane Society of the United States worked with Icahn as an adviser and pushed Tyson Foods Inc for a board seat to fight the use of gestation crates. The Humane Society's CEO at the time did not get the seat.

Icahn and his daughter said they are also concerned with other welfare issues for farm animals.