MERÅKER, Norway—The distinct smell of animal feces and soil fills the air. A slender figure, barely illuminated by a white ceiling lamp, bends down and strokes the head of a large sow. "You are a good pig, aren't you?" Jan Thomas Jenssen, 17, says softly.

Then he straightens up, pulls down his gray woolen sweater, and heads off to train for cross-country skiing. "My plan is to become a farmer, like my dad and his dad before him. But first things first."

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