Taking the general average, it may be stated, that for every pound of flesh-forming elements contained in the food of the sucking animal, it consumes respiratory compounds capable of producing one and a half pounds of fat, and this does not differ materially from the ratio subsisting between these substances in the lean animal. When the young animal is weaned, it obtains a food in which the ratio of nitrogenous to respiratory elements is maintained nearly unchanged; but the latter, in place of containing a large amount of fatty matters, is in many cases nearly devoid of these substances, and consists almost exclusively of starch and sugar, mixed most commonly with a considerable quantity of woody fibre.

A very large number of analyses of different kinds of cattle food have been made by chemists, but our information regarding them is still in some respects imperfect. The quantity of nitrogenous compounds and of oil has been accurately ascertained in almost all, but the amount of starch, sugar, and woody fibre is still imperfectly determined in many substances. This is due partly to the fact that the nitrogenous and fatty matters were formerly believed to be of the highest importance, and might be used as the measure of the nutritive value of food to the exclusion of its other constituents, and partly also to the imperfect nature of the processes in use for obtaining the amounts of woody fibre, starch, and sugar. These difficulties have now, to a certain extent, been overcome, and the quantity of fibre and of respiratory elements has been ascertained, and is introduced, so far as is known, in the subjoined table:—

Table giving the Composition of the Principal Varieties of Cattle Food.

Note.—Where a blank occurs in the oil column, the quantity of that substance is so small as to be unimportant. When the respiratory elements and fibre have not been separated, the sum of the two is given.

Nitrogenous Compounds. Oil. Respiratory Compounds. Fibre. Ash. Water.
Decorticated earth-nut cake 44·00 8·86 19·34 5·13 14·05 8·62
Decorticated cotton cake 41·25 16·05 16·45 8·92 8·05 9·28
Poppy cake 34·03 11·04 23·25 11·33 13·79 6·56
Teel or sesamum cake 31·93 12·86 21·92 9·06 13·85 10·38
Rape cake 29·75 8·63 38·72 7·30 8·65 6·95
Dotter cake 29·00 7·99 27·04 16·12 12·59 7·26
Tares, home-grown 28·57 1·30 58·64 2·50 8·99
Linseed cake 28·53 12·47 35·78 6·32 6·11 10·79
Rübsen cake 26·87 11·00 31·47 16·95 8·00 5·71
Tares, foreign 26·73 1·59 53·04 2·84 15·80
Earth-nut cake (entire seed) 26·71 12·75 45·69 3·29 11·56
Niger cake 25·74 6·58 42·18 11·15 8·12 6·23
Beans (65 lbs. per bushel) 24·70 1·59 54·51 3·36 15·84
Lentils 24·57 1·51 58·82 2·79 12·31
Linseed 24·44 34·00 30·73 3·33 7·50
Grey peas 24·25 3·30 57·99 2·52 11·94
Foreign beans 23·49 1·51 59·67 3·14 12·21
Cotton cake (with husk) 22·94 6·07 36·52 16·99 6·02 11·46
Pea-nut cake 22·25 7·62 30·25 26·97 3·71 9·20
Sunflower cake 21·68 8·94 19·05 33·00 9·33 8·00
Hempseed cake 21·47 7·90 22·48 25·16 15·79 7·21
Kidney beans 20·06 1·22 62·16 3·56 13·00
Maple peas 19·43 1·72 63·18 2·04 13·63
Madia sativa (seed) 18·41 36·55 34·59 4·13 6·32
Clover hay (mean of different species of clover) 15·81 3·18 34·42 22·47 7·59 16·53
Rye 14·20 ... 81·51 2·47 1·82 14·66
Bran 13·80 5·56 61·67 6·11 12·85
Oats 11·85 5·89 57·45 9·00 2·72 13·09
Fine barley dust 11·49 2·92 71·41 2·67 11·51
Wheat 11·48 ... 73·52 0·68 0·82 13·50
Bere 10·25 ... 62·85 10·08 2·60 14·22
Hay (mean of different grasses) 9·40 2·56 38·54 29·14 5·84 14·30
Barley 8·69 ... 64·52 9·67 2·82 14·30
Coarse barley dust 8·46 3·47 69·73 7·31 11·03
Rice dust 8·08 2·95 69·22 8·12 11·63
Oat dust 6·92 3·21 72·86 7·70 9·31
Winter bean straw 5·71 ... 67·50 6·39 20·40
Carob bean 3·11 0·41 62·51 18·60 2·80 12·57
Potato 2·81 ... 17·30 1·07 1·13 77·69
Carrot 1·87 ... 7·91 3·07 1·11 86·04
Wheat straw 1·79 ... 31·06 45·45 7·47 14·23
Barley straw 1·68 ... 39·98 39·80 4·24 14·30
Oat straw 1·63 ... 37·86 43·60 4·95 12·06
Mangold-wurzel 1·54 ... 8·60 1·12 0·96 87·78
Cabbage 1·31 ... 4·53 1·05 93·11
Turnips 1·27 0·20 4·07 1·08 1·71 91·47

It is at once obvious that in many of these descriptions of food the ratio of the flesh to the fat-forming constituents differ very widely from that existing in the milk, and this becomes still more apparent when the latter are represented in their fat equivalent, as is done for a few of them in the following table:—

Flesh forming,Respiratory, expressed in their fat equivalent,
Decorticated earth-nut cake44·016·6
Linseed cake28·526·7
Tares26·7318·8
Clover hay15·8116·8
Oats11·8528·8
Hay (mean of grasses)9·4017·9
Potato2·816·9
Wheat straw1·7912·4
Turnip1·271·8

It is especially note-worthy that those varieties of food, which common experience has shewn to promote the fattening of stock to the greatest extent, contain in many instances the smallest quantity of respiratory or fat-forming elements relatively to their nitrogenous compounds. This is especially the case with the different kinds of oil cake, the leguminous seeds, clover, hay, and turnips. On the other hand, in the grains the ratio is nearly that of one to three, or similar to that found in fat cattle; while in the straw, the excess of the respiratory elements is extremely great.

These facts appear at first sight to be completely at variance with the composition of the increase of fattening animals, as ascertained by Messrs. Lawes and Gilbert already referred to, and which have shewn that for every pound of nitrogenous compounds, nearly ten pounds of fat are stored within the animal; and it might be supposed that those kinds of food which contain the largest relative amount of respiratory elements ought to fatten most rapidly, and should be selected by the farmer in preference to oil-cakes and similar substances. But there are other matters to be considered, dependent on the complex nature of the changes attending the absorption and assimilation of the food. It must be particularly borne in mind that only a small proportion of the food consumed is stored up within the body, and goes to increase the weight of the animal. Even in the case of the milk, in which economy in the supply of nutritive matters has been most clearly attended to by nature, a considerable proportion escapes assimilation, and in the adult animal a large amount of the food passes off with the excretions. The justice of this position is apparent when it is remembered that an ox will go on day after day consuming from a hundred weight to a hundred weight and a half of turnips, three or four pounds of bean-meal or oil-cake, and a considerable quantity of straw, although its daily increase in live weight may not exceed a couple of pounds. And in this direction a very fertile field of inquiry lies open to the agricultural experimenter; for it would be most important to determine whether there are not some substances from which the nutritive matters may not be more easily assimilated than from others, and what proportion of each is absorbable under ordinary circumstances. On this point no information has yet been obtained applicable to individual feeding substances, but the experiments of Messrs. Lawes and Gilbert have shewn the quantity of the total food, and of each of its constituents, stored up in the fattening animal, and a summary of their results is contained in the following Table:—