The cows in Farmer John’s pasture lead an idyllic life. They roam through tree-shaded meadows, tearing up mouthfuls of clover while nursing their calves in tranquility. Tawny brown, compact and muscular, they are Limousins, a breed known for the quality of its meat and much sought-after by the high-end restaurants and butchers in the nearby food mecca of Maastricht, in the southernmost province of the Netherlands. In a year or two, meat from these dozen cows could end up on the plates of Maastricht’s better-known restaurants, but the cows themselves are not headed for the slaughterhouse. Instead, every few months, a veterinarian equipped with little more than a topical anesthetic and a scalpel will remove a peppercorn-size sample of muscle from their flanks, stitch up the ti…