DIGESTIVE PROCESS IN CATTLE.

King Country Chronicle, Volume VII, Issue 568, 17 May 1913, Page 2

DIGESTIVE PROCESS IN CATTLE.

The phenomenon of cud-chewing, to which singular process the ox and sheep alone of the animals of the farm subject their food, is interesting to anyone who cares to take the trouble to watch it, and, needless to say, its proper performance is of vital importance to the health and thriftineßß of the class of Btock to which the function belongs (says a veterinary surgeon). Why a horse has a comparatively small stomach and a long intestine, and the ox an enormous paunch, three other so-called "stomachs," and a short intestinal canal, why one chews its food a second time and the other does not, is not clear; but it is supposed that the function was developed far back in times when graminivorous animals were harassed by beasts of prey. They travelled in flocks or herds to the feeding grounds, bolted thier -food hurriedly, and then returned to some place of quiet and safety to chew it at leisure. There are several theories as to the exact fashion in which rumination is performed, and the relation of the several compartmenst of the stomach to the process, but the most generally accepted is the following:—Grass, hay and other rough food is, as already described, thrust half-chewed into the rumen, where the mass is slowly and deliberately churned, so that a complete mixing takes place. The essential function of the rjmen is to retain the food for rumination, macerate all fibrous substances, and fit them for cellulose digestion. Liquid and pultaceous matters may pass at once into the omasum (third, or "manifold" stomach), as well as into the rumen (first stomach or "paunch") or the reticulum (second or "honeycomb" stomach), in other terms, food coming down the oesophagus, which in passing through the rumen forms a singular groove or channel, may enter either of these reservoirs, the destination being determined by the condition in which it is swallowed. At intervals, determined by the fullness of the rumen and the quietness ot the situation, the animal lays itself out to subject the roughly masticated alimentary matter to a second chewing, and, judging by the appearance of contentment assumed by the animal, this seems to be a pleasant business.

In doing this a pellet of food is pressed, by a contraction of the rumen and reticulum, into the oesophageal groove and carried up the oesophagus, by its reverse peristaltic action, into the mouth, the act being termed "fetching the cud," where it is chewed, slowly and complacently, until well mixed with salvia, when it is swallowed again. THE TIME OCCUPIED. Colin, by whom, with Flourens, in France, the physiology of rumination has been principally worked out and on whose experiments and observations our knowledge of the process is entirely based, estimates the weight of each bolus cut off by the contraction of ihe extremity of the oesophagus at 3£oz. to 40z.; that its formation and ascent occupies about three seconds, its re-mastication about fifty seconds, and its descent after grinding as one and a half seconds. On these data he has estimated that at least seven hours out of the twenty-four are required for the process of rumination. (Smith). There is no doubt, however, that the tiem occupied, or the number of chews given to bolus, varies with the character of the food or its artificial preparation, as we shall presently see, and not only do no two cows occupy the same time, but there is no uniformity of rate or duration in the same animal. It is essential to remember that the process of chewing the cud is one which may easily be disturbed, some individuals being very easily upset. Therefore great care should be taken not to disturb or interfere with animals when chewing thecud.

| With"] reference to what happens after the bolus has been masticated, mixed with salvia and reswallowed, its course depend? upon its state of preparation. It may be returned to the rumen—coarse food may be reroasticated several times —but if finely comminuted, and always the fluid portion squeezed but before grinding of the solid mass commences, it is passed along the oesophageal groove, the lips of which contract to form a tube leading to the omasum (third stomach), where it undergoes certain changeß that have not been definitely deter mined, until it finally reaches the abotnasum (fourth or true digestive stomach), the only compartment secreting gastric juice, and where the proteids are converted into peptones It is important to note that one of the most certain signs of health is the regular and vigorous chewing of the cud, and that CESSATION OF RUMNIATAION is one of the earliest signs of a departure from health, and especially where digestive derangement exists, Cessation of rumination is not, any more than loss of apoetite, a diagnostic symptom, but "loss of cud" and "dropping the cud" is invariably associated with improper Meding or functional or organic disease of tha diges tive organs. One of the most fertile causes of loss of cud is failure to supply a sufficiency of long fodder. Not only can cattle deal efficiently with a large quantity of comparatively innutritious material, and by persistent chewing get the full value out of it, but a certain amouunt of roughness or length is essential to rumination. It is not possible to feed the cow in tabloid form, or even on the concentrated stuffs essential in the case of the fast working horse. THE PULPING SYSTEM. A quarter of a century ago, when the system of pulping, grinding and chaffing all food given to cattle was first introduced, it was hailed with delight as reducing waste to a mini mum and a good deal of waste of roots and hay went on and unthinking people talked of relieving the cow of much of the labour ef mastication and digestion, just as unpractical people

do now about cooking food for stock. Many farmers and dairymen laid down expensive plant for carrying out these processes power-driven chaff cutters, corn grinders, cake breakers and root pulpers—but it was very soon found that cattle so fed suffered from loss of cud, and consequent indigestion —mainly chronic "hoven." Many dropped the system like the proverbial "hot potato," and allowed their costly machinery to rust, but the wiser sought for the causo, and it was found to be due to an insufficiency of long fodder. In other terms, either the food was too Bhort to permit of it being formed into a bolus for regulatation, or it was already so finely comminuted as to need very little secondary matication, and consequently received only a small and insufficient admixture of saliva. As we have endeavoured to show, digestion is not a simple mechanical process, but a series of chemical change* brought about by the action of the Bucretion of various glands, of which those having their ducts opennig to the mouth, and which are excited by mastication, are of great importance. It was found that the feeding of the chaff in longer lengths—not less than two and a half inches, easily accomplished by taking a knife out of the machine, or providing one good meal daily of long hay or jtraw—enabled the cud to be easily "fetched," and ensured that it was properly "chewed," and experience goes to show that, employed in this way, the system of pulping and chaffing the food can be practised without the slightest fear of indigestion resulting. "DROPPING THE CUD," the equivalent of which in the horse is popularly known as "quidding," means the dropping from the mouth of partly-chewed food, considerable quantities of which are sometimes found in the crib or on the ground. This takes place in diseases of the mouth and dental irregularities; ren dering mastication painful, and is also one symptom of certain sub-acute forms of indigestion dependent on bad and innutritioua food. Sometimes the contents of the rumen are actually vomited, the reverse peristalsis permitted in the bovin oesophagus in "fetching the cud" favouring vomition. In describing the structure of tbe oesophagus in the bovine, reference was made to the fact that the tube is composed of red muscle throughout, and that it differs from the hone, in which the terminal portion is composed of involuntary muscle, and is so narrow, and always closely contracted, that if cut off cloße to the stomach the contents do not escape. This is one of several reasons why horses do not vomit, and conversely why cattle sometimes do. The first thing in any case of "dropping the cud" is to examine the mouth. In young animals, dental changes, and particularly the persisting crowns of deciduous molas, causa pain in mastication, or there may be disease of the buccal membrane, of the tongue, etc., for example, as commonly occurs in cases of actinomycosis. In dropping the cud on account of indigestion the animal is generally unthrifty, with depraved appetite, irregular bowels, and hidebound. A cathartic dose or saline laxative, with a change of diet, is indicated in all cases of irregularity in rumination associated with digestive derangement