Ruminants are mammals that are able to acquire nutrients from plant-based food by fermenting it in a specialized stomach prior to digestion, principally through microbial actions. The process typically requires the fermented ingesta (known as cud) to be regurgitated and chewed again. The process of rechewing the cud to further break down plant matter and stimulate digestion is called rumination. The word "ruminant" comes from the
Latin ruminare, which means "to chew over again".
The roughly
150 species of ruminants include both domestic and wild species. Ruminating mammals include cattle, goats, sheep, giraffes, yaks, deer, antelope, and some macropods.
Taxonomically, the suborder Ruminantia (also known as ruminants) is a lineage of herbivorous artiodactylas that includes the most advanced and widespread of the world's ungulates. The term 'ruminant' is not synonymous with Ruminantia. Suborder Ruminantia includes many ruminant species, but does not include tylopods and marsupials
The primary
difference between a ruminant and nonruminant is that ruminants have a four-compartment stomach. The four parts are the rumen, reticulum, omasum, and abomasum
. In the first two chambers, the rumen and the reticulum, the food is mixed with saliva and separates into layers of solid and liquid material. Solids clump together to form the cud or bolus.
The cud is then regurgitated and chewed to completely mix it with saliva and to break down the particle size. Fiber, especially cellulose and hemicellulose, is primarily broken down in these chambers by microbes (mostly bacteria, as well as some protozoa, fungi and yeast) into the three volatile fatty acids (VFAs): acetic acid, propionic acid, and butyric acid.
Protein and nonstructural carbohydrate (pectin, sugars, and starches) are also fermented.
Though the rumen and reticulum have different names, they represent the same functional space as digesta can move back and forth between them.
Together, these chambers are called the reticulorumen. The degraded digesta, which is now in the lower liquid part of the reticulorumen, then passes into the next chamber, the omasum, where water and many of the inorganic mineral elements are absorbed into the blood stream.
After this, the digesta is moved to the true stomach, the abomasum. The abomasum is the direct equivalent of the monogastric stomach, and digesta is digested here in much the same way. Digesta is finally moved into the small intestine, where the digestion and absorption of nutrients occurs.
Microbes produced in the reticulorumen are also digested in the small intestine.
Fermentation continues in the large intestine in the same way as in the reticulorumen.
The kangaroo is a marsupial from the family Macropodidae (macropods, meaning "large foot"). In common use the term is used to describe the largest species from this family, especially those of the genus Macropus: the red kangaroo, antilopine kangaroo, eastern grey kangaroo, and western grey kangaroo.
Deer (singular and plural) are the ruminant mammals forming the family Cervidae.
Species in the family include the white-tailed deer, mule deer (such as the black-tailed deer), elk, moose, red deer, reindeer (caribou), fallow deer, roe deer, pudú and chital.
Male deer of all species (except the
Chinese water deer) and female reindeer grow and shed new antlers each year. In this they differ from permanently horned animals, such as antelope, which are in the same order as deer and may bear a superficial resemblance to them.
Slow lorises are a group of several species of nocturnal strepsirrhine primates which make up the genus Nycticebus.
Found in
Southeast Asia and bordering areas, they range from
Bangladesh and
Northeast India in the west to the
Sulu Archipelago in the
Philippines in the east, and from
Yunnan province in
China in the north to the island of
Java in the south. Although many previous classifications recognized as few as a single all-inclusive species, there are now at least eight that are considered valid: the
Sunda slow loris (N. coucang),
Bengal slow loris (N. bengalensis), pygmy slow loris (N. pygmaeus),
Javan slow loris (N. javanicus),
Bornean slow loris (N. menagensis), N. bancanus, N. borneanus, and N. kayan. The group's closest relatives are the slender lorises of southern
India and
Sri Lanka. Their next closest relatives are the African lorisids, the pottos, false pottos, and angwantibos. They are less closely related to the remaining lorisoids (the various types of galago), and more distantly to the lemurs of
Madagascar. Their evolutionary history is uncertain since their fossil record is patchy and molecular clock studies have given inconsistent results.
- published: 26 Oct 2015
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