Not only does the richness of the milk vary with the nature of the food, but it varies also according to the time of the day when it is drawn, the morning milk giving 7½ per cent of cream and the evening milk 9½ per cent (Hassall). Boedecker found that the morning milk had 10 per cent of solids, while the evening milk had 13 per cent. Again, the milk first drawn at any milking is always poorer than the last drawn. The first may have only one-half, or in extreme cases one-fourth, the cream of the last. Once more, when the cow is in heat the milk becomes richer in solids (casein and butter), and contains granular and white blood cells like the colostrum, and often disagrees with the young animal living on it. Now, while these various modifications in the amount of solid matters may prove harmless to a strong and vigorous calf, they can easily be the occasion of intestinal disorder in a weaker one, or in one with health already somewhat impaired by sickness, exposure, or unwholesome buildings. The casein of the cow's milk coagulates in one solid mass, and is much less easily penetrated by the digesting fluids than the fine, flaky coagula of woman's or mare's milk. An excess of casein, therefore, thrown on an already overtaxed stomach can all the more readily induce disorder. So it is with butter fat. While a most important element in nutrition, it may be present in the stomach in such quantity as to interfere with the action of the gastric juice on the casein, and with the interruption of the natural stomach digestion the fats themselves undergo decomposition with the production of offensive and irritating fatty acids.
The milk of the very young cow is usually more watery than that of the mature animal, and that of the old cow has a greater liability to become acid. It varies much with the breed, the Channel Island cattle being notorious for the relatively large quantity of cream, while the Holsteins, Ayrshires, and Shorthorns are remarkable rather for the quantity of casein. The milk of cows fed on potatoes and grass is very poor and watery; that from cows fed on cabbage or Swedish turnips has a disagreeable taste and odor (from the former an offensive liquid has been distilled).
Cows fed on overkept, fermented, and soured rations have acid milk, which readily turns and coagulates. Thus old, long-kept brewer's grains, swill, the refuse of glucose factories, and ensilage which has been put up too green all act in this way. The same may come from disease in the cow's udder, or any general disease of the cow with attendant fever, and in all such cases the tendency is to rapid change and unwholesomeness. If the milk is drawn and fed from a pail, there is the added danger of all sorts of poisonous ferments getting into it and multiplying; it may be from the imperfect cleansing and scalding of the pail; from rinsing the pails with water that is impure; from the entrance of bacterial ferments floating in the filthy atmosphere of the stable, or from the entrance of the volatile chemical products of fermentation.
In addition to the dangers coming through the milk, the calf suffers in its digestive powers from any temporary illness, and among others from the excitement attendant on the cutting of teeth, and impaired digestion means fermentations in the undigested masses and the excessive production of poisonous ptomaines and toxins.
Whatever may be the starting or predisposing cause of this malady, when once established it is liable to perpetuate itself by contagion and to prove a veritable plague in a herd or a district.
Symptoms.—The symptoms of a diarrhea may appear so promptly after birth as to lead to the idea that the cause already existed in the body of the calf, and it usually shows itself before the end of the second week. It may be preceded by constipation, as in retained meconium, or by fetid eructations and colicky pains, as in acute indigestion. The tail is stained by the liquid dejections, which are at first simply soft and mixed with mucus with a sour odor, accompanied with a peculiar and characteristic fetor (suggesting rotten cheese), which continually grows worse. The quantity of water and mucus steadily increases, the normal predominance of fatty matters becoming modified by the presence of considerable undigested casein, which is not present in the normal feces, and in acute cases death may result in one or two days from the combined drain on the system and the poisoning by the absorbed products of the decomposition in the stomach and bowels. When the case is prolonged the passages, at first 5 or 6 a day, increase to 15 or 20, and pass with more and more straining, so that they are projected from the animal in a liquid stream. The color of the feces, at first yellow, becomes a lighter grayish yellow or a dirty white (hence the name white scour), and the fetor becomes intolerable.
At first the calf retains its appetite, but as the severity of the disease increases the animal shows less and less disposition to suck, and has lost all vivacity, lying dull and listless, and, when raised, walking weakly and unsteadily. Flesh is lost rapidly, the hair stands erect, the skin gets dry and scurfy, the nose is dry and hot, or this condition alternates with a moist and cool one. By this time the mouth and skin, as well as the breath and dung, exhale the peculiar, penetrating, sour, offensive odor, and the poor calf has become an object of disgust to all that approach it. At first, and unless inflammation of the stomach and bowels supervenes (and unless the affection has started in indigestion and colic), the belly is not bloated or painful on pressure, symptoms of acute colicky pains are absent, and the bowels do not rumble; neither are bubbles of gas mingled with the feces. The irritant products of the intestinal fermentations may, however, irritate and excoriate the skin around the anus, which becomes red, raw, and broken out in sores for some distance. Similarly the rectum, exposed by reason of the relaxed condition of the anus, or temporarily in straining to pass the liquid dejection, is of a more or less deep red, and it may be ulcerated. Fever, with rapid pulse and increased breathing and temperature, usually comes on with the very fetid character of the feces and is more pronounced as the bowels become inflamed, the abdomen sore to the touch and tucked up, and the feces more watery and even mixed with blood.
Prevention.—The prevention of these cases is the prevention of constipation and indigestion, with all their varied causes as above enumerated, the selection of a strong, vigorous stock, and, above all, the combating of contagion, especially in the separation of the sick from the healthy, and in the thorough purification and disinfection of the buildings. The cleansing and sweetening of all drains, the removal of dung heaps, and the washing and scraping of floors and walls, followed by a liberal application of chlorid of lime (bleaching powder), 4 ounces to the gallon, are indicated. Great care must be exercised in the feeding of the cow to have sound and wholesome feed and water, so apportioned as to make the milk neither too rich nor too poor, and to her health, so that the calf may be saved from the evil consequences of poisonous principles that may be produced in the body of the cow. The calves should be carefully kept apart from all calving cows and their discharges. Similarly each calf must have special attention to see that its nurse gives milk which agrees with it, and that this is furnished at suitable times. If allowed to suck, it should either be left with the cow or be fed three times a day. If it becomes hungry twice a day, it is more liable to overload and derange the stomach, and if left too long hungry it is tempted to take in unsuitable and unwholesome feed, for which its stomach is as yet unprepared. So, if fed from the pail, it is safer to do so three times daily than twice. There should be the utmost cleanliness of feeding dishes, and the feeder must be ever on the alert to prevent the strong and hungry from drinking the milk of the weaker in addition to their own. In case the cow nurse has been subjected to any great excitement by reason of travel, hunting, or carrying, the first milk she yields thereafter should be used for some other purpose and only the second allowed to the calf. Indeed, one and all of the conditions indicated above as causes should be judiciously guarded against.
Treatment.—Treatment varies according to the nature and stage of the disease. When the disease is not widespread, but isolated cases only occur, it may be assumed to be a simple diarrhea and is easily dealt with. The first object is to remove the irritant matter from stomach and bowels, and for this 1 or 2 ounces of castor oil may be given, according to the size of the calf. Reduce the milk by one-half or two-thirds. If the stools smell particularly sour, the milk may be replaced by 1 ounce calcined magnesia, and in any case a tablespoonful or two of limewater must be given with each meal. Great harm is often done by giving opium and astringents at the outset. These serve merely to bind up the bowels and retain the irritant source of the trouble; literally, "to shut up the wolf in the sheep-fold." When the offending agents have been expelled in this way, carminatives and demulcent agents may be given—1 dram of anise water, 1 dram nitrate of bismuth, and 1 dram of gum arabic, three times a day. Under such course the consistency of the stools should increase until in a day or two they become natural.
If, however, the outbreak is more general and evidently the result of contagion, the first consideration is to remove all sources of such contamination. Test the milk of the cow with blue litmus paper; if it reddens, reject the milk until by sound, dry feeding, with perhaps a course of hyposulphite of soda and gentian root, the milk is made alkaline. The castor oil or magnesia will be demanded to clear away the (now infecting) irritants, but they should be combined with antiseptics, and, while the limewater and the carminative mixture may still be used, a most valuable addition will be found in the following: Calomel, 10 grains; prepared chalk, 1 ounce; creosote, 1 teaspoonful; mix, divide into 10 parts, and give one four times a day. Or the following may be given four times a day: One dram Dover's powder, 6 grains powdered ipecacuanha; mix, divide into 10 equal parts. Injections of solutions of gum arabic are often useful, and if the anus is red and excoriated, one-half dram of copperas may be added to each pint of the gummy solution. All the milk given must be boiled, and if that does not agree, eggs made into an emulsion with barley water may be substituted. As the feces lose their watery character and become more consistent, tincture of gentian in doses of 2 teaspoonfuls may be given three or four times a day. Counter-irritants, such as mustard, ammonia, or oil of turpentine, may be rubbed on the abdomen when it becomes tender to the touch.