Healthy teeth thanks to the 'washing machine effect': Research explains tooth abrasion in cows

Ruminants like cows have developed an unusual way of digesting their food: they ingest plants, give them a rough chewing and then swallow the half-chewed mash before regurgitating it repeatedly and continuing to chew. This has clear advantages, as a research team including the University of Göttingen has shown: the regurgitated mushy food contains much less hard grit, sand and dust than the food that they first ingested.