Gosling penned an open letter to Costco CEO Craig Jelinek in June (15), urging him to take action after officials at The Humane Society of the United States released the findings of an undercover investigation, which reportedly showed the abuse and mistreatment of chickens from the retail chain's largest egg supplier.
Pitt and comedian Bill Maher threw their support behind the campaign in July (15), and now Jackass star Steve-O has written to Jelinek.
In his open letter published on Wednesday (02Sep15) and obtained by WENN, he writes, "I am horrified at how birds are warehoused - packed so tightly they are being choked by the corroded wires of their cages. These poor animals are being forced to eat, sleep, defecate, and lay eggs on top of their dead cage mates!
"Listen, I'm not excused from occasional gross behavior, but there is no excuse for forcing living beings into this kind of misery.
"I understand Costco indicated to millions of members and the public in 2007 that you would go cage-free. What are you waiting for?"
Steve-O, real name Stephen Glover, is known for taking strong stands against animal cruelty - he was recently charged with five misdemeanours, including trespassing and creating a false emergency, after he scaled a crane as part of a SeaWorld protest in Los Angeles in August (15). Last year (14) he was fined for vandalising a SeaWorld sign by the side of a highway in California.