Which brings us to McDonald's. More than a decade ago, activists from animal rights groups went to the company's executives, and they said 'Look, obviously the government's not doing its job regulating slaughterhouses, but you're the most powerful food company in the world — you could force slaughterhouses to change.'

One of the McDonald's executives who dealt with the activists is a man named Bob Langert. He's flown out from company headquarters on this day to watch the inspection. Langert acknowledges that he and his colleagues resisted the activists at first. But eventually, an activist convinced him to call Temple Grandin. And Langert says she changed everything.

"The thing I love about Temple is that she cannot be dishonest," says Langert. "It is impossible for her to be dishonest. She could care less about statements and rhetoric. Everything about her is about getting results."

He says that until Grandin came along, all he kept hearing was rhetoric. The activists kept telling him, 'Slaughterhouses are cruel, they should be more humane.' But Langert says McDonald's needed more than that: they needed to learn how to measure brutality, so they could figure out how to fix it.

Remember, McDonald's built its empire on measurements—they know if employees do a good job or not based on how many seconds they take to make a Big Mac. Langert says Temple Grandin's inspection system brings that same kind of science to the slaughterhouse.

"Now we're walking up to a pen of cattle," describes Grandin.

If workers shock the cattle with electric prods, they get marked down on Temples' chart. These workers hustle the cattle along with plastic bags. Photo: Daniel Zwerdling

By now, the latest batch of cattle has come off the truck, and Grandin tackles the next item on her inspection list: how often do workers shock the cattle with electric prods?

"Oh, I can remember watching a guy taking an electric prod and shoving it down a cow's throat," recalls Grandin. "That was absolutely horrible."

Grandin says most slaughterhouses rely on electric prods to make the animals walk through the pens, until they actually get to the plant. Her scorecard flunks a plant if more than a quarter of the cattle get shocked.

"One of the things that's been difficult for a lot of people to understand has been that you can use behavior to move your animal rather than force," explains Grandin. "If cattle or pigs are backing up in the chute all the time, and backing up and backing up, get rid of the things that scare them. Don't get out more electric prods!"

Temple Grandin says when animals get scared, she relates to them — that's how she experienced the world growing up autistic. A blackboard pointer made her panic. But she couldn't say what bothered her; she didn't speak a word until she was three.

"Well, I can remember the frustration of not being able to talk," recalls Grandin. "And I was at the school speech therapist at the time and when it was another child's turn, she' d point the pointer at me. I remember what the pointer looked like. It was one of those wooden pointers that was about 2 ½ feet long with a rubber tip on it so it looks like a bullet on the end. And she would point that at me and I would just scream. The school bell going off — that hurt my ears. Like a dentist drill going down my ears. I would scream and throw myself on the floor. It's like I still have the old animal predator circuits that all the animals have. It's like that old animal nervous system is more prevalent in me than it is in other people."

But as Grandin got older, she slowly climbed out of her hell. She went to college and got good grades. She worked at a farming magazine and a stockyards. She got a PhD in animal science, started writing landmark studies on animal behavior, and began designing machinery for slaughterhouses across the country. Then, around ten years ago, Grandin says she had a revelation and it crystallized her calling. A slaughterhouse in Alabama called her, and said they urgently needed help, so she flew down to their plant.

"That plant was an absolute nightmare," says Grandin. "They would run the cattle up a single-file chute and then run them up into a box that had a floor at a 45-degree angle. The poor cattle would just fall down. They'd then loop a chain around the back foot and drag the beast across the floor and hang him up. He'd be bellowing. I thought, 'This is absolutely the most gruesome thing I ever saw.' I started to get mad. But I've learned I can't just have a tantrum. But when I get mad, I get spurred into action."

Grandin ripped out the machinery, and she built a new kind of squeeze chute to hold the animals gently. In fact, she modeled the controls on the ones she built for her own squeeze machine, back in her bedroom in Colorado. The day she tried out her new system, Grandin herself took the controls and when the cattle stepped forward, and they slit the animals' throats, she realized that everything she'd been working toward her whole life really did make a difference. Grandin made a difference in those animals' lives at the final moment when it counts.

The cows' final seconds in the system Temple Grandin designed. Graphic: Temple Grandin

"And I did not look at the controls," recalls Grandin. "It was sort of like the box became an extension of my hands, it was almost like you could reach through the machine and hold the animal. The thing that amazed me was that you could take the two parts of the head restrainer, and if the animal's head was not in the right place, you could just reach out through the machine and move his head around. He just let me do it! You could keep the animal completely calm. It was extremely hot in Alabama and I had no feeling of the heat. I would get so relaxed doing this, it was a calmness like what people get when they are doing meditation."