DAIRY COW'S STOMACH.

Auckland Star, Volume LVIII, Issue 115, 18 May 1927, Page 23

DAIRY COW'S STOMACH.

ITS INTRICACIES AND WORKINGS.

COW COWS HANDLE THEIE FOOD,

j' It i 3 of advantage for everyone who to feed live stock for profit to Jnow something about the organs of the animal's body, and the manner by which the feed taken into the system is utilised end transformed into work, flesh, milk, wool, or other products. The subject of digestion is of first Importance, since it is by the process of digestion that the various feed subttances are changed during their progress through the digestive tract of the animal so that they can be absorbed into the system and used there to repair .wasted tissues and to provide material for the performance of all duties incidental to the maintenance of life and usefulness. The digestive tract is a long, tortuous canal, or tube, which passes through the body of the animal from end to end, and along this canal •re situated places for the storage of food or for waste materials until they are voided from the body. All along the line the food is acted upon by various materials, such as enzymes, bacteria, etc., which nrc elaborated by various organs or glands placed in the body of .the animal for that purpose. It i 3 important to remember that the digestive tract, including the stomach and the intestines, is really outside of the body proper. Their contents do not actually enter the body of the animal until they have been acted upon by the various digestive fluids and mechanical forces at work in the digestive tract, and have been absorbed through the walls of the latter in a form quite different from that in which they reached the process of mastication. In the mouth the food is put through the process of mastication, and there crushed and ground as well as nixed with the saliva, which is an alkaline fluid generously produced so as to assist in the formation of small masses of food, which are then swallowed, and, after passing through the gullet, reach the stomach. The amounts of saliva secreted by domestic animals are surprising. It has been found that a horse, for instance, fed with a ration cf 111b of hay and 111b of other dry fodder, will secrete about four times this weight of saliva, or 881b, which, in addition to about 4*lb of saliva secreted during rest, makes a total of over 911b every 24 hours. In the horse and the pig the gullet is a simple tube leading from the mouth to the stomach, ,l»ut in ruminants the gullet is expanded t into three large compartments of considerable capacity before the true stomach is reached. These are the paunch ■or rumen, the honey-comb or reticulum, and the manyplies or omasum. The true stomach of the ruminant is called the abomasum. It is common to speak of the former three as stomachs also, so that in the ruminant there are four 'stomachs to be considered instead of one.

Points to Remember. When a calf or lamb is first born, the first three stomachs are less developed than in the mature animal. The paunch in the mature animal holds yery much.more than the other three stomachs together, but in the young calf the paunch holds considerably less than the true stomach. This change ■takes place as the calf changes from 'liquid feed, such as milk, to more solid feed, such as hay and grass. With increasing age and an increased consumption of the coarser feeds the paunch gradually increases in size until, in the mature animal, it holds a very large quantity of food in storage until the process of rumination, or "chewing the cud," takes place. All ruminants such as the cow only chew their food enough to moisten it before swallowing. It Is formed into masses of suitable size to be swallowed with the aid of the taliva secreted by the glands of the mouth. The moist balls or masses pnss down the gullet, and because they are of a size to distend the gullet they Are squeezed into the paunch when they reach the esophageal groove, which is ,lnerely a slit in the gullet. When the cow has satisfied her hunger •he usually seeks a quiet place in the pasture, if she is not living under cover, er perhaps lies rather in stall or pasture, I and finishes the preparation of the food in the paunch and honeycomb for the third and fourth stomachs. This is *here the "chewing of the cud" begins. The masses of food in the paunch are forced out into the gullet by muscular action, and back into the mouth. Each mass weighs about four ounces, and 'each is chewed for about a minute with • constant mixture of saliva. After being chewed thoroughly, the mass is reswal- , lowed, and in its altered condition it •lips past the slit in the gullet and finds its way to the third, and finally 4<> the fourth stomach.

{ A Protracted Process. It takes a lonjr time finally to mastieate all of the food stored in the first 'and second stomachs. In fact, it takes 'Irom seven to eight hours each day, i»nd it will be seen that it is only the animal is at rest, or com[paratively so, that chewing the cud takes place. When working the ox is enable to chew the cud, and it does >ot take place either when the animal a sleeping, excited, or in pain. Every dairyman knows that when an animal •tops chewing its cud there is something *rong if it stops for any length of time. There is every reason, therefore, why the dairyman should give heed to this important natural habit of the cow, and when feeding, bear in ttifld its significance. The chewing of the cud is also one reason why the *ow should be kept as contented as Possible if she is to perform the work expected of her, and it is a reason why ■he should be left undisturbed as much •e possible. There are few things that •Ppeal to the experienced man as much ■a to enter a cowshed full of cattle and ™d them all f lying down, or resting JjOntentedly chewing their cuds. A» a wet indication it means that they are •*«>? well fed and that they are eealthy. if they were neither so well led nor so healthy, it is probable that Joey would not be" so contented. It ii not to be inferred from the Fjjore that tne ou i y ra j a9 i o n of the g«»t stomach is to store food for fur- £■» digestion. This is one of the prinJepal purposes of the paunch, but the ESS , " of digestion is also going on EJ}>» the food remains in the paunch. FJ* "olid food swallowed is often of a ■*«o»» nature—that is to say, with ffiat hard cells which must be broken

before the nutriment inside can become available for the body of the animal. The fluids of digestion can not easily break down these hard cell -walls, and while there are no digestive fluids secreted in the paunch, water is secreted, which moistens the cell walls and makes them more easily subject to the action of bacteria, which are present in the paunch and carry on the fermentation of the cellulose. Muscular action also tends to mix the food thoroughly in the paunch, and some of it is even more or less ground up by being pressed against the rough walls of the first stomach. The Final Stage.

After rumination and chewing of the | cud, the food, as mentioned before, | passes into the third stomach, where it i is further ground between the many folds, and from there it passes directly j into the fourth or true stomach. Here . the food is acted upon by the gastric j juice, which contains pepsin and rennin (which in the stomach of the calf yields j rennet for chee3e-making), both of: which are enzymes, and act upon the j food so as to further digest it. The pepsin acts upon the proteins and breaks them down into more easily absorbed substances, while the rennin is a provision of Nature for curdling the solid contents of milk, go that these may be retained until they can be acted upon by the pepsin, and the water in the food allowed to pass, on into the intestines. Soon after the food reaches the stomach that organ begins a series of muscular movements, which have for their object the movement of the food toward the rear or intestinal end of the stomach. This muscular action passes in waves from front to rear of the stomach, and the more liquid portions are forced to the entrance of the intestines, where a muscular valve opens and allows them to pass out of the stomach. Very little food is absorbed into the system iroiii the stomach. It is merely a portion of the alimentary tract, where the process of digestion "is furtnerea.