People for the Ethical Treatment of Animals said on its Web site it wanted to run the ad in Manitoba's Portage la Prairie Daily Graphic, which is distributed in the city near where a man stabbed a fellow passenger multiple times, then beheaded him and ate pieces of the body.
However, city editor Tara Seel said Thursday the newspaper had no intention of running the ad, which uses imagery of a victim's throat being cut, in reference to the slaughter of animals on factory farms.
"His struggles and cries are ignored ... the man with the knife shows no emotion ... the victim is slaughtered and his head cut off ... his flesh is eaten," reads the ad posted on the PETA site.
"If this ad leaves a bad taste in your mouth, please give a thought to what sensitive animals think and feel when they come to the end of their frightening journey and see, hear and smell the slaughterhouse," it says.
Lindsay Rajt of PETA said the ad was intended to be shocking and is meant to spur people to think about the terror experienced by animals who are raised and killed for food.
"Like human victims, animals in slaughterhouses experience terror when they are attacked by a knife-wielding assailant," the statement said. "We are challenging everyone who is rightly horrified by this crime to look into their hearts and consider leaving violence off their dinner plates."
Vince Weiguang Li, who immigrated to Canada from China in 2004, is charged with second-degree murder in the death of 22-year-old carnival worker Tim McLean. He has yet to enter a plea.
Thirty-seven passengers were aboard the Greyhound from Edmonton, Alberta, to Winnipeg, Manitoba, as it traveled at night along a desolate stretch of the TransCanada Highway about 12 miles from Portage La Prairie, Manitoba last Wednesday. Witnesses said Li attacked McLean unprovoked, stabbing him dozens of times.
As horrified passengers fled the bus, Li severed McLean's head, displaying it to some of the passengers outside the bus, witnesses said.
A police officer at the scene reported seeing the attacker hacking off pieces of the victim's body and eating them, according to a police report.
Li was been ordered by a judge earlier this week to undergo a psychiatric evaluation before he faces trial.
PETA's ad comes a day afterthat extolled the relaxing upside of bus travel.
The ad's tag line was "There's a reason you've never heard of 'bus rage."'