The New International Encyclopædia/Ruminant
RUMINANT (from Lat. ruminare, to chew the cud, from rumen, throat, gullet; connected with ructure, Gk. ἐρεύγειν, ereugein, OChurch Slav. rygati, to belch, Lith. atrugas, eructation, AS. roccettan, to belch). One of the group of large glazing animals which chew a cud, classified by Cuvier as an order (Ruminantia), but now regarded as a group of the suborder Artiodactyla, the cloven-hoofed or even-toed Ungulata (q.v.). The ruminants include all of the cloven-hoofed herbivores except the swine and hippopotamus, that is the chevrotains, camels, deer, giraffes, cattle, antelopes, sheep, goats, musk-ox, and some extinct families. All these are alike in that their dentition and digestive organs are adapted to that peculiar method of mastication called ‘chewing the cud.’ Except the camels, they have no incisors in the upper jaw, the front of which is occupied by a callous pad. The grass is collected and rolled together by means of the long tongue; it is firmly held between the lower cutting teeth and the pad, and then torn and cut off. In the lower jaw there generally appear to be eight incisors; but the two outer are more properly to be regarded as canines. In front of the molar teeth there is a long vacant space (diastema) in both jaws. The molars are six on each side in each jaw: their surface exhibits crescent-shaped ridges of enamel — that is, they are of the solenodont type. See Teeth; and illustration of cow's skull, under Cattle.
The stomach is composed of four distinct bags or cavities, except in the chevrotains, where the third is absent. In the camels the stomach is imperfectly divided into four chambers and has special peculiarities. (See Camel.) In all ruminants the first pouch of the stomach, into which the gullet leads, is, in the mature animal, by far the largest and is called the paunch or rumen. Into this the food first passes. It is lined with a thick membrane, presenting numerous prominent hard papillæ, secreting a fluid in which the food is soaked. The second cavity is the honeycomb bag, or reticulum, so called from its being lined with a layer of chambers like those of a honeycomb. The second pouch has also a direct communication with the æesophagus, and fluids pass immediately into it, but sometimes or partly also into the other cavities. The third pouch is the manyplies or psalterium, so called because its lining membrane forms many deep folds, like the leaves of a book, beset with small, hard tubercles. This also communicates directly with the æsophagus, by a sort of prolongation of it. The fourth pouch, which is of more elongated form than any of the others, and is second in size, is called the reed or rennet, or abomasum. It is lined with a velvety mucous membrane in longitudinal folds, and here the gastric juice is secreted. In young animals it is the largest of the four cavities, and it is only when they pass from milk to crude vegetable food that the paunch becomes enlarged, and all the parts of the complex stomach come fully into use. The food consumed passes chiefly into the first cavity, but part of it also at once into the second (as the animal wills), and when in a mashed or in a much comminuted state, into the third. When the paunch is well filled and the animal is at rest, it begins the process called chewing the cud or ruminating. This may occur while the animal is standing, but more commonly when lying down. The first step is a spasmodic movement of the paunch and diaphragm like a hiccough and a reversal of the peristaltic movement of the æsophagus, by which a ball of food is brought up into the mouth from the rumen or reticulum. It is then chewed steadily for some time until thoroughly mixed with the saliva, when it is reswallowed, but passes by the first two pouches and enters the psalterium, from which it goes on into the abomasum and intestine, which in this group is always long, as also is the cæcum. For an account of the evolution of this apparatus and the ruminant habit, see Alimentary System, Evolution of.
STOMACH OF A RUMINANT.
|a, b, probes in the gullet; retic., reticulum, psal., psalterium; abom., abomasum; ru, rumen (paunch); pylo., pylorus.|
The head of the ruminant is elongated, the neck is always of considerable length, the eyes are placed at the side of the head, and the senses of smell and hearing, as well as of sight, are extremely acute. The head in many ruminants is armed with horns, which in some are found in both sexes, in some only in the male, while in others they are entirely wanting. The ruminants are generally gregarious; they are distributed over almost the entire world, even in the coldest regions, but none are natives of Australia and comparatively few occur in America. Africa is the home of most of the species. The group is divisible into three sections: (1) Tragulina, embracing the chevrotains (Tragulidæ), which are the oldest ruminants, going back to the Eocene and Oligocene, and the extinct family Protoceratidæ of the Miocene of America, which resemble the ancestral tragulines; (2) Tylopoda, including the camels; and (3) Pecora, or horned ruminants, composed of the deer (Cervidæ), giraffes (Giraffidæ), pronghorns (Antilocapridæ), cattle, sheep, and goats (Bovidæ), and certain fossil forms. The flesh of most of the ruminants is fit to be used for human food; the fat (tallow) hardens more on cooling than the fat of other animals, and even becomes brittle. The fat, hide, horns, hoofs, hair, bones, entrails, blood, and almost all parts are useful to man.