If we now turn to the study of the composition of straw regarded from an economic point of view, we shall find that the theoretical deductions therefrom harmonise with the results of actual feeding experiments. Let us assume that 100 parts of oat-straw contain on an average—

and if the price of the straw be 30s. per ton, we shall have at that cost the following quantities of digestible substances:—

ONE TON OF OAT-STRAW, AT 30s., CONTAINS:—
lbs.
[!--30--][30] Oil 22·4
Flesh-forming principles 89·6
Sugar, gum, and other fat-forming substances 224·0
Digestible fibre 672·0
———
1,008·0
[!--31--][31] Total amount of fat-formers, calculated as starch 952·0
Add flesh-formers 89·6
———
Total amount of nutritive matter 1,041·6

We shall now compare this table with a similar one in relation to the composition of linseed cake, which will place the greater comparative value of straw in a clearer light.

A fair sample of linseed-cake contains, centesimally—

Flesh-formers 26
Oil 12
Gum, mucilage, sugar, &c. 34
Woody fibre 6
ONE TON OF LINSEED CAKE, AT £11, CONTAINS:—
lbs.
Flesh-forming principles 582·4
Oil 268·8
Gum, sugar, and other fat-formers 761·6
Woody fibre 74·4
————
1,687·2
Total amount of fat-formers, calculated as starch 1,508·0
Add flesh-formers 582·4
————
Total amount of nutriment 2,090·4

These comparisons are very instructive and important. We learn from them that we pay £11 for 2,000 lbs. of nutriment, when we purchase a ton of linseed-cake, whereas, when we invest 30s. in a ton of straw, we receive 1,000 lbs. of digestible aliment. It cannot be said that I have strained any points in favour of the straw; on the contrary, I believe that when that article is cut in proper season and well harvested, its composition will be found far superior to that detailed in the comparative analysis. It must be borne in mind, too, that I take no account of the 30 per cent. of the so-called indigestible woody fibre which straw contains, and which, I believe, is partly assimilable under ordinary circumstances, and could be rendered nearly altogether digestible by proper treatment; on the other hand, I have assumed that the woody fibre of the oil-cake is completely digestible, although I believe it is in reality less so than the fibre of straw.

It is an important point in the composition of oil-cakes, that they contain a large proportion of ready-formed fatty matters which can, with but little alteration, be at once transmuted into animal fat. There are some individuals of the genus Homo to whose stomachs fat, per se, is intolerable; nevertheless, as a general rule, fatty substances exercise a favorable influence in the process of digestion, and, either in a separate state, or intimately commingled with other aliments, constitute a large proportion of the food of man. Digestion in the lower animals is, no doubt, similarly promoted by mixing with the aliments which are to be subjected to that process, a due proportion of oily or fatty matter. Straw is relatively deficient in the flesh-forming principles, and abounds in the fat-forming elements—of which, however, the most valuable, oil, is the least abundant. Now, if we add to straw a due proportion of some substance very rich in flesh-formers and oil, the compound will possess in nicely adjusted proportions all the elements of nutrition. Perhaps the best kind of food which we could employ for this purpose is linseed meal. It contains about 24 per cent. of flesh-formers, 35 per cent. of a very bland oil, and 24 per cent. of gum, sugar, and mucilage. Linseed-cake may be substituted for linseed-meal; but the meal, though its cost is 15 per cent. greater, is, I believe, rather the better article of the two. Its flesh-formers are more soluble, and its oil thrice more abundant and far more palatable than the same principles in most samples of oil-cake. An important point, too, is, that linseed, unlike linseed-cake, is not liable to adulteration. As linseed possesses laxative properties it cannot be largely employed; the addition, however, of bean-meal—the binding tendency of which is well known—to a diet partly composed of linseed will neutralise, so to speak, the relaxing influence of the oily seed. If oil-cakes be used as an adjunct to straw, rape-cake will be found more economical than linseed-cake. If it be free from mustard, well steamed, and flavored with a little treacle, or a small quantity of locust-beans, it will be readily consumed, and even relished, by dairy and fattening stock.