"The caterpillar becomes a butterfly, the pig becomes a sausage, that is the law of nature." From birth to supermarket, 3 experiments on the well-being of farmed pigs are discussed by 2 biologists, 1 philosopher, 1 animal keeper, and 2 trainees from the pig research station of the Institut National de la Recherche Agronomique in Saint-Gilles in Brittany. Between scientific documentary and journalistic tract, this is a subjective vision of the practices of scientific objectivation in a French institution.