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
Coprophagia serves the same purpose within these animals as rumination (cud-chewing) does in cattle and sheep. Cattle in the United States are often fed chicken litter. There are concerns that the practice of feeding chicken litter to cattle could lead to bovine spongiform encephalopathy (mad-cow disease) because of the crushed bone meal in chicken feed. The U.S. Food and Drug Administration regulates this practice by attempting to prevent the introduction of any part of a cow's brain or spinal cord into livestock feed. Other countries, like Canada, have banned chicken litter for use as a livestock feed. The young of elephants,