Vast herds of ruminant ungulates populate the grasslands and forests. In the rumen, food eaten by the ruminant is fermented by microbes. This is also where the ruminant digests the microbes produced in the rumen. Selenodont teeth are the type of molars and premolars commonly found in ruminant herbivores. Rennet is a complex set of enzymes produced in the stomachs of ruminant mammals. It is extensively used for ruminant livestock in Latin America. The reticulum is the second chamber in the alimentary canal of a ruminant animal. The enzyme lysozyme has adapted to facilitate digestion of bacteria in the ruminant abomasum. Ivermectin is routinely used to control parasitic worms in the gastrointestinal tract of ruminant animals. It is widely used in ruminant animal feeds. They have small, unspecialized stomachs by ruminant standards, and high nutrition requirements. However, their anatomy and method of digestion differs significantly from that of a four-chambered ruminant. Polioencephalomalacia (PEM) is the most common thiamine deficiency disorder in young ruminant and nonruminant animals. In most ruminant species, a single pelvic thrust occurs during copulation. Ruminant urolithiasis associated with oxalate ingestion has been reported.