"In Flanders, the yearly loss of the necessary matters in the soil is completely restored by covering the fields with ashes of wood or bones, which may, or may not, have been lixiviated. The great importance of manuring with ashes has been long recognized by agriculturists as the result of experience. So great a value, indeed, is attached to this material in the vicinity of Marburg, and in the Wetterau,—two well-known agricultural districts,—that it is transported, as a manure, from the distance of eighteen or twenty-four miles. Its use will be at once perceived, when it is considered that the ashes, after being washed with water, contain silicate of potass exactly in the same proportion as in the straw, and that their only other constituents are salts of phosphoric acid."
It is well known that phosphate of lime, potass, silecia, carbonate of lime, magnesia, and soda are discharged in the excrement and urine of the cow; and this happens when they are not adapted to assimilation as well as when present in excess. If it is clearly proved that the bones of a cow are weak, then we should be inclined to prescribe phosphates; if they are brittle, we should prescribe gelatinous preparations; but not in the form of bone dust: we should use linseed, which is known to be rich in phosphates. At the same time, the general health must be improved.
It is well known that some cows cannot be fattened, although they have an abundance of the best kind of fodder. In such cases, we find the digestive organs deranged, which disturbs the equilibrium of the whole animal economy. The food may then be said to be a direct cause of disease.
The effects of insufficient food are well known; debility includes them all. If there is not sufficient carbon in the food, the animal is deprived of the power of reproducing itself, and the cure consists in supplying the deficiency. At the same time, every condition of nutrition should be considered; and if the function of digestion is impaired, we must look to those of absorption, circulation, and secretion also, for they will be more or less involved. If the appetite is impaired, accompanied by a loss of cud, it shows that the stomach is overloaded, or that its function is suspended: stimulants and tonics are then indicated. A voracious appetite indicates the presence of morbid accumulations in the stomach and bowels, and they should be cleansed by aperients; after which, a change of diet will generally effect a cure. When gas accumulates in the intestines, we have evidence of a loss of vital power in the digestive organs; fermentation takes place before the food can be digested.
The cure consists in restoring the lost function. Diarrhœa is generally caused by exposure, (taking cold,) or by eating poisons and irritating substances; the cure may be accomplished by removing the cold, and cleansing the system of the irritants. Costiveness often arises from the absorption of the fluids from the solids in their slow progress through the intestines; exercise will then be indicated. An occasional injection, however, may be given, if necessary. General debility, we have said, may arise from insufficient food; to which we may add the popular practice of milking the cow while pregnant, much of which milk is yielded at the hazard of her own health and that of her fœtus. Whatever is taken away from the cow in the form of milk ought to be replaced by the food. Proper attention, however, must be paid to the state of the digestive organs: they must not be overtaxed with indigestible substances. With this object in view, we recommend a mixed diet; for no animal can subsist on a single article of food. Dogs die, although fed on jelly; they cannot live upon white bread, sugar, or starch, if these are given as food, to the exclusion of all other substances. Neither can a horse or cow live on hay alone: they will, sooner or later, give evidences of disease. They require stimulants. Common salt is a good stimulant. This explains why salt hay should be occasionally fed to milch cows; it not only acts as a stimulant, but is also an antiseptic, preventing putrefaction, &c.
A knowledge of the constituents of milk may aid the farmer in selecting the substances proper for the nourishment of animals, and promotive of the lacteal secretion; for much of the food contains those materials united, though not always in the same form. "The constituents of milk are cheese, or caseine—a compound containing nitrogen in large proportion; butter, in which hydrogen abounds; and sugar of milk, a substance with a large quantity of hydrogen and oxygen in the same proportions as in water. It also contains, in solution, lactate of soda, phosphate of lime, (the latter in very small quantities,) and common salt; and a peculiar aromatic product exists in the butter, called butyric acid."—Liebig.
It is very difficult to explain the changes which the food undergoes in the animal laboratory, (the stomach,) because that organ is under the dominion of the vital force—an immaterial agency which the chemist cannot control. Yet we are justified in furnishing the animal with the elements of its own organization; for although they may not be deposited in the different structures in their original atoms, they may be changed into other compounds, somewhat similar. Liebig tells us that whether the elements of non-azotized food take an immediate share in the act of transformation of tissues, or whether their share in that process be an indirect one, is a question probably capable of being resolved by careful and cautious experiment and observation. It is possible that these constituents of food, after undergoing some change, are carried from the intestinal canal directly to the liver, and that there they are converted into bile, where they meet with the products of the metamorphosed tissues, and subsequently complete their course through the circulation.
This opinion appears more probable, when we reflect that as yet no trace of starch or sugar has been detected in arterial blood, not even in animals that have been fed exclusively with these substances.
The following tables, from Liebig's Chemistry, will give the reader the difference between what is taken into the system and what passes out.
FOOD CONSUMED BY A COW IN TWENTY-FOUR HOURS.