Ruminant

Ruminants
Rough illustration of a ruminant digestive system
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Artiodactyla
Families
Antilocapridae Bovidae Camelidae Cervidae Giraffidae Moschidae Tragulidae

A ruminant is any even-toed, hooved mammal (order Artiodactyla) that digests its food in two steps, first by softening it within the animal's first stomach, known as the rumen, then regurgitating the semi-digested mass, now known as cud, and chewing it again. Most ungulates have a four-chambered stomach (camelids have three chambers), lack upper incisors, and have two-toed feet. Ruminating mammals include cattle, goats, sheep, giraffes, American Bison, European bison, yaks, water buffalo, deer, camels, alpacas, llamas, wildebeest, antelope, pronghorn, and nilgai.

The process of again chewing the cud to further break down plant matter and stimulate digestion is called "ruminating." Taxonomically, the suborder Ruminantia includes all those species except the camelids (camels, llamas, alpacas, etc.), which are Tylopoda. Therefore, the term "ruminant" is not synonymous with Ruminantia.

Overview and description

Ruminants belong to the order In Artiodactyla, even-toed ungulates, the axis of the leg passes between the third and fourth toes. The weight of most even-toed ungulates is born evenly on the third and fourth toe of each foot with the other toes being absent, or vestigial in the case of most deer. Hippopotamuses and pigs have four functional toes on each foot (Nowak 1983).

• Nowak, R. M., and J. L. Paradiso. 1983. Walker's Mammals of the World. Baltimore: Johns Hopkins University Press.

Suborder Ruminantia

   * Family †Amphimerycidae
   * Infraorder Tragulina (paraphyletic)
         o Family †Prodremotheriidae
         o Family †Hypertragulidae
         o Family †Praetragulidae
         o Family Tragulidae: chevrotains, 6 living species in 4 genera
         o Family †Leptomerycidae
         o Family †Archaeomerycidae
         o Family †Lophiomerycidae
   * Infraorder Pecora
         o Family Moschidae: musk deer, 4 living species in one genus
         o Family Cervidae: deer, 49 living species in 16 genera
         o Family Giraffidae: giraffe and okapi, 2 living species in 2 genera
         o Family Antilocapridae: pronghorn, one living species in one genus
         o Family Bovidae: cattle, goats, sheep, and antelope, 135 living species in 48 genera

Except for hippopotamuses, peccaries, and pigs, all even-toed ungulates digest their food by the process of rumination. Their stomachs are divided into chambers, three for camels and mouse deer and four for the other families (Nowak 1983).

Most ruminants belong to the Ruminantia suborder and have a fore-stomach with four chambers. These 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, chewed slowly to completely mix it with saliva and to break down the particle size. Fiber, especially cellulose and hemi-cellulose, is primarily broken down into the three volatile fatty acids, acetic acid, propionic acid and butyric acid in these chambers by microbes (bacteria, protozoa, and fungi). Protein and non-structural carbohydrate (pectin, sugars, starches) are also fermented.

The nine species of chevrotain, also known as mouse deer, make up the family Tragulidae. In other respects, however, the chevrotains have primitive features, closer to non-ruminants such as pigs. They do not have horns or antlers, but both sexes possess enlarged upper canines Other pig-like features include the presence of four toes on each foot,

Chevrotain&oldid=258563742

Tylopoda (meaning "padded foot") is a suborder of the mammalian order Artiodactyla, containing the camel family Suborder Tylopoda: camels and llamas

Although considered ruminants—any even-toed, hooved animal that digests its food in two steps, first by eating the raw material and regurgitating a semi-digested form known as cud, then eating (chewing) the cud—camelids do not belong to the suborder Ruminantia but rather Tylopoda. Ruminantia includes the commonly known ruminants of cattle, goats, sheep, giraffes, bison, buffalo, deer, antelope, and so forth. The camelids differ from those of Ruminantia in several ways. They have a three-chambered rather than a four-chambered digestive tract; an upper lip that is split in two with each part separately mobile; an isolated incisor in the upper jaw; and, uniquely among mammals, elliptical red blood cells and a special type of antibodies lacking the light chain, besides the normal antibodies found in other species.

Even 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 last chamber, the abomasum. The abomasum is the direct equivalent of the monogastric stomach (for example that of the human or pig), 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 reticulo-rumen are also digested in the small intestine. Fermentation continues in the large intestine in the same way as in the reticulorumen.

Almost all the glucose produced by the breaking down of cellulose and hemicellulose is used by microbes in the rumen, and as such ruminants usually absorb little glucose from the small intestine. Rather, ruminants' requirement for glucose (for brain function and lactation if appropriate) is made by the liver from propionate, one of the volatile fatty acids made in the rumen ^{[citation needed]}.

Religious importance

In Abrahamic religions, a distinction between clean and unclean animals approximately falls according to whether the animal ruminates. The Law of Moses in the Bible allowed only the eating of animals that had split hooves and "that chew the cud" , a stipulation preserved to this day in the Kashrut. Some believe that the Koran considers a mammal halal only if it is ruminant. This is not true. See Dhabihah and Halal.

Other uses

The verb to ruminate has been extended metaphorically to mean to thoughtfully ponder or to meditate on some topic. Similarly, ideas may be chewed on or digested. Chew the (one's) cud is to reflect or meditate.

See also

• Monogastric
• Digestive Physiology of Herbivores - Colorado State University

References

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