Читать книгу Special Report on Diseases of Cattle - Lowe - Страница 12

Diseases of the digestive organs are very common among cattle, and may often be traced to defects in feeding. The first three stomachs of the larger ruminants hold the feed for a long time, during which period it is subjected to macerating, mixing, and straining processes in preparation for entrance into the fourth or true stomach. The straining is accomplished through the medium of the manyplies or book, while the paunch, or rumen, with its adjunct, the waterbag, is concerned in the macerating, kneading, and mixing, as well as in regurgitation for rumination or the chewing of the cud. The action of the first three stomachs is merely preparatory to digestion. Thus it would seem that as a result of their complex anatomical and functional arrangement the feed of the ox, when of good quality and wholesome, is in the most favorable condition possible for the digestive process when it reaches the fourth stomach, where true digestion first takes place. The location and arrangement of the stomachs are shown in Plates I and II.

If the feed is of improper character, or is so given that it can not be cared for by the animal in a normal way, false fermentations arise, causing indigestion, and possibly, later, organic disease. In feeding cattle there are a number of important considerations apart from the economy of the ration, and some of these are noted below.

Feeds must not be damaged by exposure to the weather, by frost, by molds, or by deleterious fermentations.

Damaged feeds retard or prevent digestion, and sometimes they contain or cause to be generated substances that irritate the digestive tract, or are distinctly poisonous to the animal. For example, hay that was rained on severely during curing has not only lost a part of its nutritive value through a washing-out process, but what remains is not so readily available as in good hay. Roots that have been frozen are likely to irritate and injure the digestive tract. Grass eaten with frost on it may cause severe indigestion. All moldy feeds are not injurious, for some molds appear to have no influence on the process of digestion, but those of other species may not only retard digestion and cause local injury to the digestive organs, but may cause general poisoning of a severe and fatal type.

The following molds have been shown (Dammann) to be dangerous in respect to the production of the morbid conditions enumerated:

Tilletia caries grows chiefly in wheat and may be found with the grain, thus appearing in the bran or meal. It causes paralysis of the throat and spinal cord and irritation of the digestive tract. The rusts, such as Puccinia graminis, P. straminis, P. Coronata, and P. arudinacea, cause colic and diarrhea, and in some cases partial paralysis of the throat. The rusts that occur on clovers, beans, and peas cause very severe irritation of the lining membrane of the mouth and throat, resulting sometimes in gangrene of this tissue.

Polydesmus exitans grows on the leaves of rape and turnips, appearing in early summer. This fungus is very irritating to the mouths and feet of cattle, causing severe inflammation and the formation of a false membrane. In some instances this condition has been mistaken for foot-and-mouth disease, but it can be differentiated by the absence of the blister that is characteristic of that disease and by the further fact that it is nontransmissible.

Polytrincium trifolii, which grows on clover, causing it to become black, causes severe irritation of the stomach and intestines of cattle feeding upon it.

Feeds must not contain too large a proportion of woody fiber or of indigestible substances. If the dry matter ingested or the bulk of the feed is very great on account of the small proportion of digestible matter, it is impossible for the great mass to be moistened properly with and attacked by the digestive juices. In consequence of this, abnormal fermentations arise, causing indigestion and irritation of the digestive organs. On the other hand, a ration too concentrated, and especially too rich in protein, is not suitable, because, after a meal, the animal must have a certain feeling of fullness in order to be comfortable and quiet, and the digestive organs require a relatively large volume of contents to fill them to the point where secretion is properly stimulated and their activity is most efficient. If too much protein is in the ration there is a waste of expensive feed, and the tendency is for the animal to become thin. It is evident that a cow can not thrive on concentrated feeds alone, even though these contain in assimilable form all the nutritive materials needed for perfect support. It is because bulk is necessary that the standard of about 25 pounds of dry matter per cow per day has been reached by experimenters. There is no objection to feeding grain or meal separately to a cow, provided enough bulky feed is fed at another time in the day to keep the digestive tract sufficiently distended.

In changing the ration, and especially in making radical changes, as at the beginning and the end of the pasturing season, the change should be made gradually, so that the digestive organs may accommodate themselves to it. After the digestive organs and juices have from long practice become adjusted to the digestion of a certain feed, which is then suddenly withheld and another of quite different character and properties is substituted, the second feed is not well digested; it may even irritate the digestive canal. It is often observed that cattle lose from 25 to 100 pounds when turned on pasture from dry stable feed. This loss can readily be prevented by not shocking the digestive organs by a sudden change of diet.

Regularity in feeding has much to do with the utilization of the ration, and gross irregularity may cause indigestion and serious disease.

Water for live stock should be as free from contamination and as nearly pure as that used for household purposes. When practicable it is well to warm the water in the winter to about 50° F. and allow cattle to drink often.