For Janice Schindler, 28, who was a vegan for five years and is now the general manager of the Meat Hook butcher shop in Brooklyn, the animal in question was a turkey at a “Kill Your Own Thanksgiving Dinner” event at a local farm.

“It was really morbid. I was the only one who signed up,” she said. “I’d never killed anything before. Turkeys are such large animals. But when you put them in a poultry cone upside down, they completely relax. Then you can cut an artery. It stuns them and they bleed. I spent the rest of the day working the eviscerating station. It was super-gross, but I found it fascinating.”

That experience was the gateway to her training as a butcher, which she began immediately afterward.

Ms. Schindler’s transformation from vegan to ethical butcher was similar to that of several butchers I spoke with. Hers began in high school: As a member of the National FFA Organization (better known as the Future Farmers of America) in Lucerne Valley, Calif., she was charged with caring for a baby lamb as it grew from a tiny ball of fleece to a bleating, prancing adolescent.

“Nothing prepared me for the emotional earthquake of selling that lamb for meat,” she said. “His name was Frederick.”

That was the first identity crisis, she said, that led her to become a vegan. Her second came in college, when she returned to eating meat after learning that the soybean and corn monocultures that accounted for much of her vegan diet were wreaking havoc on the environment.

“I felt I was being lied to as a consumer every time I’d go into Trader Joe’s and see a fake farm on the package of a G.M.O. soy burger,” she said. “I knew it was up to me to find an alternative food system.”