The Farmer's Veterinarian: A Practical Treatise on the Diseases of Farm Stock

by Charles William Burkett

DIGESTION OF THE FOOD

Before these different constituents of the plant can be used as food for animals, they must be prepared for absorption into the system of the animal. This preparation takes place in the mouth, œsophagus tube, the stomach, and the intestines, aided by the various secretions incident to digestion and absorption. Any withholding of any essential constituent has its result in inefficiency or illness of the animal.

Withhold ash materials, for instance, from the food, or supply an insufficient quantity, and the fact will be evidenced by poor teeth, deficient bone construction and poor health in general. Let the feeding ration be short in protein, and the result will be shown in the flesh and blood. Let the carbohydrates and fat be withheld or supplied insufficiently, and energy will be denied and a thrifty condition will not be possible.

The supply of these different constituents in the proper proportion gives rise to the balanced ration; and is concerned in a treatise of this kind only in so far as it has to do with disease or health. For, remember this fact: live stock are closely associated with right feeding. If foods be improperly prepared, or improperly supplied, or the rations poorly balanced, with too much of one constituent and too little of another, the effect will be manifest in an impoverished condition of the system. That means either disease, or disease invited.

Not only must these facts be considered, but other matters given recognition also. The greater part of the trouble of the stockman in the way of animal diseases is due to some disturbance of the digestive system, or to the water supply, or to ventilation, or to the use to which the animal is put from day to day. Attention to the details of digestion has its reward in thrifty, healthy stock; a lack of this attention brings trouble and either a temporary ailment or a permanent disease.

Process of Mastication.

—Food is taken in the mouth, where it is masticated by means of the teeth, lips, cheeks, and the tongue. While the process of mastication is taking place there is being poured into the mouth large quantities of saliva, which softens the food and starts the process of digestion. The active principle of saliva is a soluble ferment, called ptyalin, that converts the starch of food into sugar. The amount of saliva that is poured into the food is very great, being often as much as one-tenth of the weight of the animal. This ferment is active after the teeth have been formed, which explains why it is not advisable to feed much starchy food to children before their teeth have begun development.

The food, after being ground and mixed with the saliva fluid, goes to the stomach. With the horse and hog the stomach is a single sac not capable of holding very large quantities of food; with the cow and sheep, on the other hand, we find a large storehouse for holding food—a storehouse that is divided into four compartments, the rumen or paunch, reticulum, omasum, and the abomasum. The first three communicate with the gullet by a common opening. The cud is contained in the first and second stomachs, and, after it has been masticated a second time, it passes to the third and fourth, and to the bowels, where the process of digestion is continued.

DISEASED KIDNEY

The kidney of the hog is pictured here. As a rule it is usually impossible to diagnose kidney troubles in hogs and similar lower animals.

Gastric Juice.

—From this it will be noticed that chewing the cud is an act in the process of digestion; it refers only to rechewing the food so as to get it finer and better ground for digestion. While in the stomach the saliva continues the digestion of the starchy matter and is assisted by the gastric fluid that pours in from the lining of the stomach, which converts the protein or albuminoids into peptones. The fatty matter is not acted upon at this point. There are three constituents of gastric juice, which affect the changes in the food. These are pepsin, rennet, and acid. With rennet you are acquainted. It is used in the kitchen, in the making of cheese, and is obtained from the stomach of calves or other young animals. Pepsin, also obtained directly from the stomach, is now a conspicuous preparation in medicine. The food, after leaving the stomach, goes into the bowels and is acted upon by secretions of the liver and pancreas or sweetbreads. It should be noted in passing that no secretion enters the first three divisions of the ruminant’s stomach. It is only in the fourth or true stomach that the gastric juice is found.

The Stomach Churn.

—While food is in the stomach it is subjected to a constant turning movement that causes it to travel from the entrance to the exit or intestines. When it passes into the small intestines it is subjected to the action of bile and pancreatic juices, which have principally to do with the breaking up of the fat compounds. Both resemble, to a certain extent, saliva in their ability to change starch into sugar.

The secretion of the bile comes from the liver and the pancreatic juice from the pancreas or sweetbreads, and both are poured into the intestines near the same point, so that they act together. The ferments they contain act in the following ways: They change starch into sugar, fat into fatty compounds, they curdle milk, and convert protein compounds into soluble peptones.

The process of digestion is finally ended in the intestines, where absorption into the system takes place. There is no opening at all from the bowels into the body, but the digestive nutriment is picked up by the blood when handed into the body from the intestines by means of countless little cells called villi, that line the walls of the intestines. These villi cells have little hair-like projections extending into the intestines, which constantly move; these protrusions, as they move about, catch on to the digested nutriment, draw it into the cells themselves, where it is handed on to the blood, when it is later on distributed to all parts of the body. You can realize that an immense number of these absorption cells are present when the length of the intestine is considered. In the ox the intestine is nearly 200 feet long. After the nutriment is drawn from the food the undigested portions are voided periodically as feces or dung.

STOMACH OF RUMINANT

The four main divisions of the ruminant’s stomach are pictured here. The first three divisions are the store-houses for food until it is fully prepared for the fourth stomach or abomasum.

Absorption of the Nutriment.

—Digestion, therefore, is a dissolving process; food is admitted to the system by means of cells. You remember that all plant food first passes into a soluble state before it can enter the roots and be conveyed to the parts of the plants that require additional food for growth. In the case of plants the entrance is by means of the root hairs. In the case of the animal, entrance in the body is by means of the villi cells that line the intestines. From this we see that digestion is both an intricate and delicate process. Any loss of appetite, any disturbance of the digestion work, and any irregularity of the bowels bear decided results, one way or the other, to the rest of the system; and any disturbance of the body at other points, although having no direct relation to the digestion system, sooner or later affects the digestion and in so doing causes additional trouble.

Directly affecting digestion may be improper food, either liquid or solid; and over-exercise or not enough of it may prove troublesome, for exercise is clearly related to digestion. When the digestion process is disturbed, air or gas may accumulate in the stomach or bowels and give rise to colic or hoven. A watery action of the intestines, due to inflammation or irritation, may lead to dysentery and enteritis; or some obstruction like a hair-ball or a clover fuzzy ball, or the knotting of the intestines, may occur, temporarily or permanently impairing digestion so seriously often as to cause death itself.