The manufacture of cheese requires the prior solidification of milk in a vat. The milk curdling process has been reproduced by men from the observation of the digestion of young ruminants. Their stomachs contain a natural enzyme, the rennet, which accelerates the milk coagulation, thus facilitating its digestion and prolonging its conservation. The rennet used to make Cantal DPO cheese is extracted from the gastric juice of the fourth pouch of the stomach of young ruminants, mainly calves, slaughtered before weaning.