Relative Value and Manurial Properties of Purchased Food. 653 



value of different articles of food. Then we have in all feeding ma- 

 terials the woody fibre, which, being indigestible, possesses no feeding 

 value. 



Lastly, we have the mineral matters, which play an important part 

 in the animal economy, inasmuch as they supply bone materials, and 

 also the various salts which are requisite in the formation of blood, and 

 are invariably present in the juices of flesh and other secretions. 



On examining these different classes of food, we find that the rela- 

 tive proportions of their chief feeding constituents vary exceedingly. 

 The nitrogenous or flesh-producing substances, as they are generally 

 called, although in reality they do not produce, par excellence, 

 butcher's meat, are particularly abundant in all kinds of oil-cake 

 and leguminous grains, more especially in decorticated cotton-cake, 

 and next to it in order, earthniit-cake. The proportion of nitrogen in 

 leguminous seeds very nearly approaches that in oil-cake. Cereal 

 grains contain on the average only half the proportion of nitrogenous 

 substances contained in leguminous products. Now the feeding value 

 of the articles of food given to stock really depends not so much on 

 the amount of flesh-forming constituents, or in other words, ou the 

 amoimt of nitrogen which the different kinds of food are shown by 

 analysis to contain, as on the proportion of ready-made fat, and sub- 

 stances capable of producing it. It must be remembered that in 

 butcher's meat we have invariably a mixture of lean, muscle, fibre, and 

 fat ; and the mixture is much more readily produced from food, having 

 a fair proportion of albuminous matter with an excess of starchy sub- 

 stances or of ready-made fat, than from food containing an excess of 

 flesh-forming constituents — albumen, caseine, gluten, or their equiva- 

 lents. The food, then, which is richest in nitrogen, is not exactly 

 that which produces butcher's meat most readily, or at the lowest 

 cost. The value of oil-cakes depends in a gi'eat measiu'e on the 

 amount of ready-made fat which they contain. Hence a foreign cake, 

 poor in oil and very hard- pressed, is not equal as a meat -producing 

 auxiliary food to good English oil-cake not much squeezed in the oil- 

 mill. This perhaps is one reason why hard-pressed Marseilles cake is 

 not so well adapted for the fattening of stock as it is for young stock. 

 The reason why foreign cake is inferior to English cake as a fattening 

 material is, that well-made English cake is generally richer in ready- 

 made fat and oil. 



Eegarded merely as feeding materials, the various food-constituents 

 follow each other in value in the following order : (1) ready-made fat 

 and oil ; (2) starch, sugar, and pectine ; (3) nearly equal to starch or 

 sugar is quite young digestible cellular fibre ; (4) then come the albu- 

 minous substances — gluten, caseine, vegetable albumen, and analogous 

 materials ; (5) lastly, we have mineral substances and woody fibre, 

 possessing scarcely any feeding value. 



The money value of food, however, as I have already intimated, does 

 not depend simply upon the actual amount of feeding materials which 

 it contains, but also upon the value of the fertilising elements which 

 pass through the animal into dimg. Let us, therefore, inquire which 



