Every day, cows (Bos taurus) eat around two per cent of their body weight – around 11 kilograms – in vegetation. Their diet naturally consists of fibrous grasses, legumes and hay, as well as the occasional piece of fruit. As a food source, grass is incredibly difficult to extract nutrition from. Simple stomachs, such as those of humans or canines, aren’t able to digest it, whereas animals called ruminants, such as cattle, sheep and deer, have evolved a complex stomach system that can.
The journey through the bovine digestive system starts with the mouth, designed to puree plants as opposed to tearing through meat. Unlike the pointed teeth of the world’s carnivores and omnivores, a cow’s bottom jaw is lined exclusively with flat incisors and molars to grind down clumps of grass – which have already been torn up by its tongue – against the leathery layer that makes up the top jaw, called a dental pad. During mastication, or chewing, cows move their jaws from side to side to pulverise grass into tiny pieces for easier digestion. Once ingested, the chewed grass makes its way down the oesophagus and through a network of stomach chambers collectively known as the ruminant digestive system. Unlike what you may have heard, cows do not have four individual stomachs to digest their food. Instead their stomachs are made up of four distinct chambers that food passes through, releasing more and more nutrients as it goes.