The Stock-Feeder's Manual Part 12

It is clear, then, from what I have stated, that neither the amount of flesh-formers, nor of fat-formers, contained in a given quant.i.ty of a substance is a measure of its nutritive value; nevertheless it would be incorrect to infer from this that the numerous a.n.a.lyses of feeding substances which have been made are valueless. On the contrary, I am disposed to believe that the composition of these substances, when correctly stated by the chemist, enables the physiologist to determine pretty accurately their relative alimentary value. Theory is certainly against the a.s.sumption that food is valuable in proportion to its content of nitrogen; nor has practice less strongly disproved its truth.

An ill.u.s.tration drawn from the nutrition of plants will make this matter more apparent. Every intelligent agriculturist knows that guano contains nitrogen and phosphoric acid; both substances are indispensable to the development of plants, and therefore it would be incorrect to estimate the manurial value of the guano in proportion to the quant.i.ty of nitrogen it was capable of yielding. If the value of manures were determined only by their per-centage of nitrogen--a mode by which certain chemists still estimate the nutritive value of food--then woollen rags would be worth more than bones, and bones would be more valuable than superphosphate of lime. The truth is, that the a.n.a.lysis of feeding stuffs and manures is sometimes of little value if the condition in which the const.i.tuents of these substances exist be undetermined. For example, the a.n.a.lysis of one manure may show it to contain 40 per cent.

of phosphate of lime, and three per cent. of ammonia, whilst, according to a.n.a.lysis, another fertiliser may include 20 per cent. of phosphate of lime, and two per cent. of ammonia. Viewed by this light solely, the first manure would be considered the more valuable of the two, whereas it might, in reality, be very much inferior. If the phosphate of lime in the manure, containing 40 per cent. of that body, were derived from coprolites or apat.i.te, and its ammonia from horns, the former would be worth little or nothing, and the latter, by reason of its exceedingly slow evolution from the horns, would possess a very low value. If, on the contrary, the phosphate of lime, in the manure comparatively poor in phosphate, were a const.i.tuent of bones, and its ammonia ready formed (say as sulphate of ammonia), then, its value, both commercial and manurial, would be far greater than the other.

In estimating the money value of an article of food, we should omit such considerations as the relative adjustment of its flesh-formers and fat-formers, and its suitability to particular kinds of animals, as well as to animals in a certain stage of development. The manure supplied to plants contains several elements indispensable to vegetable nutrition; and, although the agriculturist most commonly purchases all these elements combined in the one article, still he frequently buys each ingredient separately. Ammonia is one of these principles, and, whether it be bought _per se_, or as a const.i.tuent of a compound manure, the price it commands is invariable. This principle should prevail in the purchase of food: each const.i.tuent of which should have a certain value placed upon it; and the sums of all the values of the const.i.tuents would then be the value of the article of food taken as a whole. There are, no doubt, practical difficulties in the way which prevent this method of valuation from giving more than approximatively correct results; but are there not precisely similar difficulties in the way of the correct estimation of the value of a manure according to its a.n.a.lysis? There are several const.i.tuents of food, the money value of which is easily determinable: these are sugar, starch, and fat. No matter what substance they are found in, the nutritive value of each varies only within very narrow limits. The value of cellulose and woody fibre is not so easily ascertained, as it varies with the age and nature of the vegetable structure in which these principles occur. There is little doubt but that the cellulose and fibre of young gra.s.s, clover, and other succulent plants, are, for the most part, digestible; and we should not be far astray if we were to a.s.sume that four pounds weight of soft fibre and cellulose are equivalent to three pounds weight of starch. As to old hard fibre, we are not in a position to say whether or not it possesses any nutrimental value worth taking into account. The estimation of the value of the flesh-forming materials is far more difficult than that of sugar, starch, pectine compounds, and fat. The nitrogenous const.i.tuents of food must be in a highly elaborated state before they are capable of being a.s.similated. In seeds--in which vegetable substances attain their highest degree of development--they probably exist in the most digestible form, whilst much of the nitrogen found in the stems and leaves of succulent plants, is either in a purely mineral state, or in so low a degree of elaboration as to be unavailable for the purpose of nutrition. But even plastic materials, in a high degree of organisation, present many points of difference, which greatly affect their relative alimental value; for example, many of them are naturally a.s.sociated with substances possessing a disagreeable flavor: and as their separation from these substances is often practically impossible, the animal that consumes both will not a.s.similate the plastic matters so well as if they were endowed with a pleasant flavor. In seeds and other perfectly matured vegetable structures, the flesh-formers may exist in different degrees of availability. The nitrogen of the _testa_, or covering of the seeds, will hardly be so a.s.similable as that which exists in their cotyledons. The solubility of the flesh-formers--provided they be highly elaborated--is a very good criterion of their nutritive power.

In linseed the muscle-forming substances are more soluble than in linseed-cake--the heat which is generally employed in the extraction of oil from linseed rendering the plastic materials of the resultant _cake_ less soluble, and diminis.h.i.+ng thereby their digestibility, as practice has proved.

From the considerations which I have now entered into, it is obvious that the chemical a.n.a.lysis of food substances as generally performed, though of great utility, does not afford strictly accurate information as to their commercial value, and still less reliable in relation to their nutritive power. At the same time, they as clearly establish the feasibility of a.n.a.lyses being _made_ whereby the money value of feeding-stuffs may be estimated with tolerable exact.i.tude. Let the chemist determine the presence and relative amounts of the ingredients of food-substances, and--if it be possible so to do with a degree of exactness that would render the results useful--place on each a money value. This done, let the physiologist and the feeder combine the food in such proportions as they may find best adapted to the nature, age, and condition of the animal to be fed.

It is to be regretted that the market price of feeding stuffs is not, in consequence of our defective knowledge, strictly determined by their nutritive value, for if such were the case, the feeder would merely have to adapt each to the nature and condition of his stock. Even amongst practical men there prevails, unfortunately, great diversity of opinion as to the relative nutritive value of the greater number of food substances; and I am quite certain that many of these command higher prices than others which in no respect are inferior. It would lead me too far from my immediate subject were I to enter minutely into the consideration of such questions as--whether an acre of gra.s.s yields more or less nutriment than an acre of turnips? I shall merely describe the composition and properties of gra.s.s and of turnips, and of the various other important food substances, and compare their nutritive power, so far as comparisons are admissible; but I shall say but little on the subject of the various economic and other conditions which affect the production of forage plants. When I shall have described the chemical nature and physical condition of the various articles of food, and the results of actual feeding experiments made with them, the feeder will then be in a position to determine which are the most economical to produce or to purchase.

SECTION II.

PROXIMATE CONSt.i.tUENTS OF VEGETABLES.

The saccharine, or amylaceous substances const.i.tute the most abundant of the proximate const.i.tuents of plants. They are composed of carbon, hydrogen, and oxygen. I shall briefly describe the more important members of this group of substances, namely, starch, sugar, inulin, gum, pectin, and cellulose.

_Starch_, or _fecula_, occurs largely in dicotyledonous seeds, peas, &c., and still more abundantly in certain monocotyledonous seeds, such as wheat and barley. It const.i.tutes the great bulk of many tubers and roots--for example, the potato and tapioca. It consists of flattened ovate granules, which vary in size according to the plant. In the beetroot they are 1/3500 of an inch in diameter, whilst in _tous les mois_ they are nearly 1/200 of an inch in diameter. Most of the starch granules are marked by a series of concentric rings. Starch is heavier than water, and is insoluble in that fluid when cold; neither is it dissolved by alcohol or ether. When heated in water having a temperature of at least 140 Fahrenheit, it increases greatly in volume, and acquires a gelatinous consistence. When the water is allowed to cool, a portion of the starch becomes insoluble, whilst another portion remains in solution; the latter form of starch is sometimes termed _amidin_, from the French word for starch, _amidon_. When dry starch is heated to 400 Fahr., it is converted, without any change in its composition, into a soluble gum-like substance, termed _dextrin_, or British gum. On being boiled in diluted sulphuric acid it is converted into a kind of sugar; and the same effect is produced by fermentation--for example, in the germination of seeds. Fresh rice contains 82, wheat 60, and potatoes 20 per cent. of starch. This substance const.i.tutes a nutritious and easily digestible food, but alone cannot support life. Arrowroot is only a pure form of starch.

_Sugar_ occurs less abundantly in plants than starch. There are several varieties of this substance, of which the kinds termed cane sugar (_sucrose_) and grape sugar (_glucose_), are only of importance to agriculturists. The former enters largely into the composition of the sugar-cane, the beetroot, the sugar-maple, the sorgho gra.s.s, pumpkins, carrots, and a great variety of other plants. Grape sugar is found in fruits, especially when dried--raisins and figs--in malted corn, and in honey. In the sugar-cane there is 18 per cent., and in the beetroot 10 per cent. of sugar.

_Cane sugar_, when pure, consists of minute transparent crystals. It is 1-6/10 heavier than water, and is soluble in one-third of its weight of that fluid. By long-continued boiling in water it is changed into uncrystallizable sugar, or treacle, by which its flavor is altered, but its sweetening power increased.

_Grape sugar_ crystallizes in very small cubes, of inferior color as compared with cane sugar crystals. It dissolves in its own weight of water, being three times less soluble than sucrose. In sweetening power one part of cane sugar is equal to 2-1/2 parts of grape sugar; but there is probably little if any difference, between the nutritive power of the two substances.

_Inulin_ is a substance somewhat resembling starch. It does not occur in large quant.i.ties. It is met with in the roots of the dandelion, chicory, and many other plants.

_Gum_ is an abundant const.i.tuent of plants. The kind termed gum arabic, so largely employed in the arts, is a very pure variety of this substance. Common gums are said to be essentially composed of a very weak acid--_gummic_, or _arabic_ acid--united with lime and potash.

The solution of gum is very slightly acid, and has a mucilaginous, ropy consistence: it is almost tasteless. _Mucilage_, or _ba.s.sorin_, is simply a modified form of gum, which, though insoluble in water, forms a gelatinous mixture with that fluid. It exudes from certain trees--the cherry for example--and exists largely in linseed and other seeds. Gums are nutritious foods, but it is probable that they are not equal in alimental power to equal weights of starch or sugar.

_Vegetable jelly_, or _pectin_, is almost universally diffused throughout the vegetable kingdom. It is owing to its presence that the juices of many fruits and roots possess the property of gelatinizing.

It is soluble in water, but prolonged boiling destroys its viscous property. _Pectose_ is a modification of pectin; it is insoluble in water. According to Fremy, the hardness of green fruits is due to the presence of pectose; which is also found in the cellular tissue of turnips, carrots, and various other roots.

_Cellulose_ is a fibrous or cellular tissue, allied in composition to starch. It is the most abundant const.i.tuent of plants, and forms the very ground-work of the vegetable mechanism. Linen, cotton, and the pith of the elder and other trees are nearly pure forms of cellulose.

Ligneous, or woody tissue (_lignin_) is indurated cellulose, hardened by age. It is almost identical in composition with cellulose. Pure cellulose is white, colorless, tasteless, insoluble in water, oil, alcohol, or ether. It is heavier than water. Sulphuric acid is capable of converting it into grape, or starch sugar. In its fresh and succulent state cellulose is digestible and nutritious; but in the form of ligneous tissue it opposes a very great resistance to the action of the digestive fluids. Digestible cellulose is probably equal in nutritive power to starch.

_Oils and fats_ occur abundantly in vegetables, more particularly in their seeds. In the seeds of many cruciferous plants the proportion of fat and oil exceeds 35 per cent. The oils and fats termed _fixed_ are those which possess the greatest interest to agriculturists; the _volatile oils_ being those which confer on certain plants their fragrant odour. There are a great variety of vegetable oils, but the proximate const.i.tuents of most of them are chiefly _stearin_, _margarin_, _olein_, and _palmitin_.

_Stearin_ is a white crystalline substance, sparingly soluble in alcohol and ether, but insoluble in water. There are two or three modifications of this substance, but they do not essentially differ from each other.

The melting point varies from 130 to 160 Fahr. Stearin is the most abundant of the fats.

_Margarin_ presents the appearance of pearly scales. It is the solid fat present in olive oil, and it is also met with in a great variety of fats and oils. It melts at 116 Fahr.

_Olein_ is the fluid const.i.tuent of oils and fatty substances. It resists an extreme degree of cold, without solidifying. There are several modifications of this body--the olein of olive oil being somewhat different from that of castor oil; the olein of linseed is sometimes termed _linolien_.

_Palmitin._--This fat occurs in many plants, but as it makes up the great bulk of palm oil, it has been termed palmitin. It is white, and may be obtained in feathery-like ma.s.ses. Its melting point varies from 114 to 145, there being, according to Duffy, three modifications of this substance.

The fats and oils are lighter than water. They contain far more carbon and hydrogen, and less oxygen, than are found in the sugars and starches. They all consist of acids (stearic, palmitic, &c.) united with glycerine. On being boiled with potash or soda, the latter take the place of the glycerine, which is set free, and a _soap_ is produced.

The fatty acids strongly resemble the fats. In nutritive power, one part of fat is equal to 2-1/2 parts of starch or sugar.

The Alb.u.minous substances contain, in addition to the elements found in starch, nitrogen, sulphur, and phosphorus. _Alb.u.men_, _fibrin_, and _legumin_ const.i.tute the three important members of the "Nitrogenous"

const.i.tuents of plants.

_Alb.u.men_ is an uncrystallizable substance. It is soluble in water, unless when heated to 140 deg. Fahr., at which temperature it coagulates, _i.e._, becomes solid and insoluble. The _gluten_ of wheat is composed chiefly of alb.u.men, and of bodies closely allied to that substance.

_Fibrin_, when dried, is a hard, h.o.r.n.y, yellow, solid body. It contains a little more oxygen than is found in alb.u.men. This substance is best known as a const.i.tuent of animals, and it does not appear to be abundant in plants. The portion of the gluten of wheat-flour, which is insoluble in boiling alcohol, is considered by Liebig and Dumas to be coagulated fibrin.

In the seeds of leguminous and a few other kinds of plants large quant.i.ties of a substance termed _legumin_ are found. It resembles the casein, or cheesy ingredient of milk; indeed, some chemists consider it to be identical in composition with that substance. When pure, it is pearly white, insoluble in boiling water, but soluble in cold water and in vinegar. The saline matters found in plants are always a.s.sociated with the alb.u.minous bodies; the latter, therefore, form the bones as well as the muscles of animals.

A great many substances are found in plants, such as wax, mannite, "extractive matter," citric, malic, and other acids, of the nutritive value of which very little is known. The substances described in this section const.i.tute, however, at least 95 per cent. of the weight of the vegetable matters used as food by live stock.

SECTION III.

GREEN FOOD.

_The Gra.s.ses._--More than one-half the area of Great Britain and Ireland is under pasture; the gra.s.ses, therefore, const.i.tute the most important and abundant food used by live stock. The composition of the natural and artificial gra.s.ses is greatly influenced by the nature of the soil on which they are grown, and by the climatic conditions under which they are developed. Many of them are almost worthless, whilst others possess a high nutritive value. Amongst the most useful natural gra.s.ses may be enumerated Italian rye-gra.s.s, Meadow barley, Annual Meadow-gra.s.s, Crested dogstail-gra.s.s, c.o.c.ksfoot-gra.s.s, Timothy or Meadow catstail-gra.s.s, and Sweet vernal-gra.s.s. Amongst gra.s.ses of medium quality I may mention common Oatlike-gra.s.s, Meadow foxtail gra.s.s, Smooth and rough stalked Meadow-gra.s.s, and Waterwhorl-gra.s.s. There are very many gra.s.ses which are almost completely innutritious, and which ought, under no circ.u.mstances, to be tolerated, although too often they make up the great bulk of the herbage of badly-managed meadows and pastures.

Such gra.s.ses are, the Meadow soft-gra.s.s, Creeping soft-gra.s.s, False brome-gra.s.s, and Upright brome-gra.s.s. The rough-stalked Meadow-gra.s.s, though spoken favorably of by some farmers, is hardly worthy of cultivation, and the same may be said of many of the gra.s.ses which have a place in our meadows and pastures. (See "a.n.a.lyses of Natural Gra.s.ses in a Fresh State, by Dr. Voelcker," on next page.)

The _Schraeder brome_ is a perennial lately introduced into France. It is described as an exceedingly valuable forage crop, and one which is admirably adapted for the feeding of dairy cows. It would be desirable to give it a trial in these countries. The composition (which is very peculiar) of this plant is stated to be as follows, when dry:--

a.n.a.lYSIS OF SCHRaeDER BROME HAY.

Water 16281 Nitrogenous matters 23443 Fat 3338 Starch gum, &c. 22549 Cellulose (fibre) 19843 Ashes 14546 ------- Total 100000

a.n.a.lYSES OF NATURAL GRa.s.sES IN A FRESH STATE, BY DR. VOELCKER.

+---------------------------------------------------------------------------+ KEY: A.--Water. B.--Alb.u.minous or Flesh-forming Principles. C.--Fatty Matters. D.--Respiratory Principles: Starch, Gum, Sugar. E.--Woody Fibre. F.--Mineral Matter or Ash. G.--Date of Collection. +-----------------------------+-----+-----+-----+------+------+-----+-------+ A. B. C. D. E. F. G. +-----------------------------+-----+-----+-----+------+------+-----+-------+ Anthoxanthum odoratum-- Sweet-scented vernal gra.s.s 8035 200 67 854 715 124 May 25 Alopecurus pratensis-- Meadow foxtail gra.s.s 8020 244 52 859 670 155 June 1 Arrhenatherum avenaceum-- Common oat-like gra.s.s 7265 354 87 1121 937 236 July 17 Avena flavescens-- Yellow oat-like gra.s.s 6040 296 104 1866 1422 272 June 29 Avena p.u.b.escens-- Downy oat-gra.s.s 6150 307 92 1916 1334 201 July 11 Briza media-- Common quaking gra.s.s 5185 293 145 2260 1700 417 June 29 Bromus erectus-- Upright brome gra.s.s 5957 378 135 3319 211 " 23 Bromus mollis-- Soft brome gra.s.s 7662 405 47 904 846 136 May 8 Cynosurus cristatus-- Crested dogstail gra.s.s 6273 413 132 1964 980 238 June 21 Dactylus glomerata-- c.o.c.ksfoot gra.s.s 7000 406 94 1330 1011 154 " 13 Ditto, seeds ripe 5257 1093 74 1261 2054 261 July 19 Festuca duriuscula-- Hard fescue gra.s.s 6933 370 102 1246 1183 166 June 13 Holcus lanatus-- Soft meadow gra.s.s 6970 349 102 1192 1194 193 " 29 Hordeum pratense-- Meadow barley 5885 459 94 2005 1303 254 July 11 Lolium perenne-- Darnel gra.s.s 7143 337 91 1208 1006 215 June 8 Lolium italic.u.m-- Italian rye-gra.s.s 7561 245 80 1411 482 221 " 13 Phleum pratense-- Meadow catstail gra.s.s 5721 486 150 2285 1132 226 Poa annua-- Annual meadow gra.s.s 7914 247 71 1079 630 59 May 28 Poa pratensis-- Smooth-stalked meadow gra.s.s 6714 341 86 1415 1249 195 June 11 Poa trivialis-- Rough-stalked ditto 7360 258 97 1054 1011 220 " 18 Gra.s.s from water meadow 8758 322 81 398 313 128 Apr. 30 Ditto, second crop 7453 278 52 1117 876 224 June 26 Annual rye-gra.s.s 6900 296 69 1289 1247 199 " 8 +-----------------------------+-----+-----+-----+------+------+-----+-------+

Most of the gra.s.ses here mentioned were a.n.a.lysed when in flower.

_Tussac Gra.s.s_ (_Dactylis caespitus_) is recommended as an excellent plant to grow on very poor, wet, or mossy soils.[26] It is an evergreen gra.s.s, somewhat resembling coltsfoot. It is relished by cattle.

a.n.a.lYSIS OF TUSSAC GRa.s.s BY JOHNSTONE.

Lower part. Upper part.

Water 8609 7517 Flesh-formers 247 479 Sugar, gum, &c. 462 681 Woody fibre (with a little alb.u.men) 568 1186 Ash 114 137 ------ ------ Total 10000 10000

The "artificial gra.s.ses" embrace the clovers, vetches, lucerne, and a few other plants, some of which are seldom cultivated.

a.n.a.lYSES OF DIFFERENT KINDS OF CLOVER, BY DR. ANDERSON.

+--------------------------------------------- KEY: A.--Water.

B.--Dry Substances.

C.--Ash.