Adulteration of Linseed Cake.—The great drawback to the use of linseed-cake is the liability of the article to be adulterated. The sophistication is sometimes of a harmless nature, if we except its injurious effect on the farmer's pocket; but not unfrequently the substances added to the cakes possess properties which completely unfit them to be used as food. Amongst the injurious substances found in linseed and linseed-cake I may mention the seeds of the purging-flax, darnel, spurry, corn-cockle, curcus-beans, and castor-oil beans. Several of these seeds are highly drastic purgatives, and they have been known to cause intense inflammation of the bowels of animals fed upon oil-cake, of which they composed but a small proportion. Amongst the adulterations of linseed-cake, which lower its nutritive value without imparting to it any injurious properties, are the seeds of the cereals and the grasses, bran, and flax-straw. Little black seeds belonging to various species of Polygonum, are very often present in even good cakes; they are very indigestible, but otherwise are not injurious. Rape-cake is stated to be occasionally used as adulterant of the more costly linseed, but I have never met with an admixture of the two articles.
The only way in which a correct estimate of the value of linseed-cake can be arrived at is by a combined microscopical and chemical analysis; but as the feeder is not always disposed to incur the cost of this process, he should make himself acquainted with the characteristic of the genuine cake, in order to be able to discriminate, as far as possible, between it and the sophisticated article. I will indicate a few of the more prominent features of cake of excellent quality, and point out a few simple and easily-performed tests, which may serve to detect the existence of gross adulteration. Good cake is hard, of a reddish-brown color, uniform in appearance, and possesses a rather pleasant flavor and odour. The adulterated cake is commonly of a greyish hue, and has a disagreeable odour. A weighed quantity of the cake—say 100 grains—in the state of powder should be formed into a paste with an ounce of water; if it be good, the paste will be light colored, moderately stiff, and endowed with a pleasant odour and flavor. If the paste be thin, the presence of bran, or of grass seeds, is probable. The latter are easily seen through a magnifying-glass; indeed, most of them are readily recognisable by the unassisted eye: they may, therefore, be picked out, and their weight determined. Sand—a frequent adulterant—may be detected by mixing a small weighed quantity of the powdered cake with about twelve times its weight of water, allowing the mixture to stand for half an hour, and collecting and weighing the sand which will be found at the bottom of the vessel employed. If there be bran present it will be found lying on the sand, and its structure is sufficiently distinct to admit of its detection by a mere glance. There are a great variety of linseed-cakes in the market, of which the home-made article is the best. On the Continent the oil-seeds are subjected to the action of heat in order to obtain from them a greater yield of oil. Their cakes, therefore, contain less oil, and their flesh-forming principles are less soluble, in comparison with British linseed-cake. Next to our home-made oil-cakes, the American is the best. Indeed, I have met with some American cakes which were equal to the best English.
Rape Cake.—The use of rape-cake was limited almost completely to the fertilising of the soil until the late Mr. Pusey, in a paper published in the tenth volume of the Journal of the Royal Agricultural Society of England, advocated its employment as a substitute for the more costly linseed-cake. The recommendation of this distinguished agriculturist has not been disregarded; and since his time the use of this cake as a feeding stuff has been steadily on the increase, and at the present time its annual consumption is not far short of 50,000 tons.
In relation to the nutritive value of rape-cake there exists considerable diversity of opinion. Certain feeders assert that animals fed upon it go out of condition; others, whilst admitting that stock thrive upon it, maintain the economic superiority of linseed-cake; whilst a third set believe rape-cake to be the most economical of feeding-stuffs. How are we to account for these great differences of opinion—not amongst theorists, be it observed, but amongst practical men? It is not difficult to explain them away satisfactorily. Rape-cake and linseed-cake are about equally rich in muscle and fat-forming principles; and, supposing both to be equally well-flavored, there can be no doubt but that one is just as nourishing as the other. But it so happens that a large proportion of the rape-cake which comes into the British market possesses a flavor which renders it very disagreeable to animals. One variety—namely, the East Indian—is almost poisonous, whilst the very best kind is slightly inferior to linseed-cake. Now, if an experiment with a very inferior kind of rape-cake and a good variety of linseed-cake were tried, who can doubt but that the results would be very unfavorable to the former article? Mr. Callan,[!--35--][35] of Rathfarnham, county Dublin; Mr. Bird,[!--36--][36] of Renton Barns, and some other feeders, who found rape-cake to be worse than useless, experimented, in all probability, with an adulterated article, for they do not appear to have had the cake analysed. On the other hand, those whose experience with rape-cake has proved favorable, must have employed the article in a genuine state, fresh, and moderately well-flavored. It is noteworthy that amongst the advocates for the use of rape-cake as a substitute—partly or entirely—for the more costly linseed-cake, are to be found the most successful feeders in England and Scotland. Horsfall, Mechi, Lawrence, Bond, Hope, and many other feeders of equal celebrity, have assigned to rape-cake the highest place, in an economic point of view, amongst the concentrated feeding stuffs. Mr. Mechi says:—"I invariably give to all my animals as much rape-cake as they choose to eat, however abundant their roots or green food may be. It pays in many ways, and not to do this is a great pecuniary mistake. Even when fed on green rape, they will eat rape-cake abundantly. My cattle are now under cover, eating the steamed chaff, rape-cake, malt-combs, and bran, all mixed together in strict accordance with the proportions named by Mr. Horsfall in the Journal of the Royal Agricultural Society, vol. xviii., p. 150,[!--37--][37] which I find by far the most profitable mode of feeding bullocks and cows." Mr. Hope, of Edinburgh, states that rape-cake is the best substitute for turnips, and that, excepting cases where spurious kinds had been used, he never knew bullocks or milch cows to refuse it. This gentleman states that it is best given in combination with locust-beans, or a mixture of locust-beans and Indian corn; and suggests the proportions set down in the tables as the best adapted for lean cattle; but I think about two-thirds of the quantities would be quite sufficient.
| Feed per week. | Per week. | ||
|---|---|---|---|
| lbs. | s. | d. | |
| Rape-cake at £5 15s. per ton | 8 | 2 | 10½ |
| Do. do. | 10 | 3 | 7 |
| Mixture of two-thirds rape-cake and one-third locust-beans £6 | 8 | 3 | 0 |
| Do. do. | 10 | 3 | 9 |
| Rape-cake, locust-beans, and Indian Corn in equal proportions | 8 | 3 | 2½ |
| Do. do. | 10 | 3 | 11¼ |
An intelligent Scotch dairy farmer bears the following testimony in favor of this cake:—
I have tried pease-meal, bean-meal, oat-meal, and linseed-cake, and after carefully noting the results, I consider rape-cake, weight for weight, at least equal to any of them for milch cows; and if I give the same money value for each, I get at least one-third more produce, and the butter is always of a very superior quality. Two years ago, I took some of my best oats (41 lbs. per bushel), and ground them for the cows, and although I was at about one-third more expense, I lost fully one-third of the produce that I had by using rape-cake. I always dissolve it by pouring boiling water on it, and give each cow 6 lbs. daily. I have tried a larger quantity, and found I was fully repaid for the extra expense. I generally use it the most of the summer, but always during the spring months. A number of my neighbours who have tried it all agree that it is the best and cheapest feed for milch cows they have used.—North British Agriculturist, Edinburgh, February 29, 1860.
The best kinds of rape-cake come from Germany and Denmark. When neither too old nor too fresh, and of a pale-green color, these foreign cakes are tolerably well-flavored, and are but slightly inferior to good linseed-cake. Most varieties of this cake, however, contain a small proportion of acrid matter, which often renders them more or less distasteful to stock, more particularly to cattle. This substance may be rendered quite innocuous by steaming or boiling the cake; either of these processes will also, according to Mr. Lawrence, destroy the disagreeable flavor which mustard-seed—a frequent adulterant of rape-cake—confers upon that article. Molasses or treacle is an excellent adjunct to the cake, as it serves in a great measure to correct its somewhat unpleasant flavor. Carob, or locust-beans, answer, perhaps better, the same purpose. It is better, as a general rule, to give less rape-cake than linseed-cake, unless the pale-green kind to which I have referred is obtainable; that variety may be largely employed. The animals should be gradually accustomed to its use. At first, in the case of bullocks, they should get only 1 lb. per diem, and the quantity should be gradually increased to about 4 lbs.; but I would not advise, under any circumstances, a larger daily allowance than 5 lbs. Given in moderate amounts, it will, supposing it to be of fair quality, be found to give a better return in meat than almost any other kind of concentrated food; and, what is of great importance, it will not injuriously affect the animal's health. "Our experience of the use of rape-cake," says Mr. Lawrence, "thus used (cooked), extends over a period of ten years of feeding from 20 to 24 bullocks annually. We have not had a single death during that period, and the animals have been remarkably free from any kind of ailment."
Rape-cake of good quality possesses a dark-green color (the greener the better), and when broken exhibits a mottled aspect—yellowish and dark-brown spots. Sometimes a tolerably good specimen has a brownish color; but the German and Danish cakes are always of a greenish hue. The odor is stronger than that of linseed-cake, and differs but little from that of rape-oil. The only serious adulteration of rape-cake is the addition to it of mustard-seed—sometimes accidentally—less frequently, as I believe, intentionally. This sophistication admits of easy detection. Scrape into small particles about half an ounce of the cake, add six times its weight of water, form the solid and liquid into a paste, and allow the mixture to stand for a few hours. If the cake contain mustard the characteristic odor of that substance will be evolved, and its intensity will afford a rough indication of the amount of the adulterant. As some specimens of genuine rape-cake possess a somewhat pungent odor, care must be taken not to confound it with that of mustard; but, indeed, it is not difficult to discriminate the latter. The paste of rape-cake which contains an injurious proportion of mustard, has a very pungent flavor. Rape-cake improves somewhat if kept for say six months; but old cake is worse than the fresh article.