Cud stretched, forming a vacuum in the gullet that sucks the semi-liquid stomach content into the esophagus. From the esophagus it is taken back to the mouth with retro peristaltic movements. When the stomach content, or the cud, arrives in the mouth of the ruminant, it is pushed against the palate with the tongue to remove excess liquid, the latter is swallowed and the solid material is chewed thoroughly so the cattle can extract the minerals present in the cud brought to the surface during rumination. The function of rumination is that food is physically refined to expose more surface area
Kosher animals that naturally live in Canaan, except for primates, and equids (horses, zebras, etc.), which are not mentioned in Leviticus as being either ritually clean or unclean, despite their importance in warfare and society, and their mention elsewhere in Leviticus. In an attempt to help identify animals of ambiguous appearance, the Talmud, in a similar manner to Aristotle's earlier "Historia Animalium", argued that animals without upper teeth would always chew the cud and have split hoofs (thus being ritually clean), and that no animal with upper teeth would do so; the Talmud makes an exception for the case of the camel