The contribution of the research group set up by Rérat in the early 1960s in Jouy-en-Josas, and then expanded to Rennes, is summarised. As digestive processes are a major key to the nutritional status of monogastric animals, original methodologies based on advanced experimental surgery were developed in the pig to quantify the digestion and absorption yield, to know their factors of variation, and to understand their physiological and nutritional consequences. The group also extended its expertise to the control of food intake, the role of the nervous system and regulatory peptides, and several biomedical gut-related topics.