216 On the Theoretical and Practical Value of 
stock or for milch-cows, contain more phosphate of lime than 
feeding materials which are richer in non-nitrogenous substances, 
and therefore more suitable for fattening stock. Provision is thus 
made, in food which is rich in nitrogenous substances, to meet 
the extra demand of young stock for the mineral matter of the 
bony structure. 
From the preceding observations it will be gathered that the 
following^ is the order of the nutritive value of the constituents, 
of food. 
1. Oil and fatty matters. 
2. Sugar, starch, and analogous carbon-hydrates. 
3. Albuminous or nitrogenous compounds. 
4r. Digestible cellular fibre. 
5. Indigestible woody fibre. 
6. Mineral matters or ash. 
Manukial Value of Purchased Food. 
Practical men are well aware that the manure produced by 
fattening stock liberally supplied with corn or cake possesses 
greater fertilising powers than the dung from store-cattle ; and 
they also know in a general way that the manure produced by 
cattle or sheep fed upon cake in addition to roots is more 
valuable than that of animals fed upon roots and hay alone. 
In the selection of purchased foods for stock, it is important 
to consider how much of the cost-price of the food should be 
charged to the manure account, and how much should be allowed 
for its feeding- value. This is by no means an easy matter, for 
although it may be ascertained which are the elements of the 
food that pass into the dung, and their relative proportions 
may be determined with tolerable precision, the practical 
benefit resulting from the use of the dung produced from various 
kinds of food will greatly vary on light and on heavy land, and 
on different soils varying much in their physical and chemical 
properties. Hence it is difficult to put upon the manure a money- 
value which will be generally accepted as correct. liowever, 
the only way to escape from this difficulty appears to be to 
value the fertilising constituents of the food which pass into 
the dung at the rates at which they can be severally bought in 
the manure-market, and to adopt subsequently such modifications 
of the total estimated value as may be suggested by the experience 
of farmers residing in dificrent localities. 
Generally speaking, different articles of food of the same class 
differ far less in their feeding-value than in their manure-value. 
For instance, it will make comparatively little difference, so fai? 
as the increase in the live-weight of the animal is concerned, 
