Humans are eating nearly twice as much meat as they were 50 years ago, and it's created a food system that's "unsustainable." That's the latest expert testimony in the trial of Toronto animal rights activist Anita Krajnc, who's charged with giving water to pigs en route to a Burlington, Ont., slaughterhouse.

Thursday was the last day of testimony of the trial. Krajnc has pled not guilty to mischief for pouring water into the mouths of pigs in a trailer outside Fearman's Pork Inc.

The trial has included testimony from experts in animal behaviour and pig intelligence, among other subjects. Krajnc's lawyers — James Silver and Gary Grill — say this is relevant because it shows Krajnc believed she was acting in the public good.

Tony Weis, a Western University assistant professor of geography, was the last of five defence witnesses. He said on Thursday that the average person ate 23 kilograms of meat per year in 1960. That's grown to about 43 kilograms of meat today.

By 2050, he said, projections show the world will have as many as 10 billion people, and humans will eat an average of more than 50 kilograms of meat per year. Livestock and their feed use large swaths of land and resources, he said.

"I don't think it's a system that's going to be able to sustain the world."

Here's a recap of Thursday's testimony:

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Krajnc, co-founder of Toronto Pig Save, has also said her mischief charge is a chance to put factory farming and the treatment of livestock on trial.

Farm groups, meanwhile, say all this is irrelevant. Krajnc was tampering with someone else's product, they say. And Halton police say they had no way to know Krajnc was giving the pigs water and not some other liquid.

The incident stems back to June 22, 2015, when Krajnc poured water through the grates of a metal trailer filled with pigs outside Fearman's Pork Inc. Krajnc maintains the pigs were clearly panting and in distress.

Armaiti May, a veterinarian, used a screen shot from this Toronto Pig Save video to illustrate her point in court that the pigs appeared to be breathing as fast as 180 breaths per minute.

Here's a breakdown of what has happened so far during the trial:

Aug. 24

Truck driver Jeffrey Veldjesgraaf was the first Crown witness. Justice David Harris watched a video of a tense exchange between Krajnc and Veldjesgraaf. In the video, Veldjesgraaf told her to stop giving water to the pigs. "These are not humans, you dumb frickin' broad," he said.

Aug. 25

Oxford County hog farmer Eric Van Boekel was a Crown witness. His testimony revolved around how pigs are "processed" and transported to Fearman's Pork Inc. That particular load was worth about $45,000, he said. Van Boekel was questioned about previous environmental infractions.

​Aug. 26

Veterinarian Armaiti May was the first defence witness. She analyzed the Toronto Pig Save video and told the court the pigs in the video appeared to be in severe distress.

Toronto Pig Save volunteers give water to pigs heading to slaughter in Burlington. One of them, Krajnc, now faces criminal mischief charges. (Anita Krajnc/Facebook)

Oct. 3

Krajnc testified in her own defence. "I just find it unfathomable that someone would be charged for giving thirsty animals water," she said. "In the three years we've given water to pigs, police have been present, so we took that as an endorsement."

Nov. 1

Lori Marino, a neuroscientist and founder of the Kimmela Center for Animal Advocacy, testified about the intelligence and sentience of pigs. Then nutrition expert David Jenkins from the University of Toronto discussed how a plant-based diet impacts human health.

The Crown and defence will make closing arguments on March 9.