Fertilizers and Feeding Stuffs. o81 



owner to buy. if, for instance, he requires the foodstuffs for the 

 feeding- of young- stock, then the proportion of proteins should be 

 high as compared with that of non-proteins, for the proteins are 

 particularly concerned with the building- up of tissues. On the other 

 liand, for animals only moderately worked or for those in store condi- 

 tion it is better to have foods rich in fats and carbohydrates, the con- 

 stituents which are sources of heat and energy in the animal system, 

 for there is comparatively little waste of tissues in the body in cases 

 like these, so the proportion of protein matter in the food can be 

 appreciably lower. 



Other Factors Governing the Feeding Value of a. Foodstajf. 



The value of a food depends very largely upon its chemical 

 composition, but its mechanical condition, palatability, digestibility, 

 method of preparation, etc., have all a great influence also upon its 

 feeding value. To take the question of mechanical condition, for 

 instance, mealie meal is far more thoroughly digested than the whole 

 or partially broken grain, for the smaller the particles of the food 

 are the larger is the surface exposed to the action of the digestive 

 juices. Again, it is not of much use putting a highly nutritious food 

 like some of the oilcakes before an animal if it has no taste for it and 

 lelfuses to consume it, but it must })e remembered, however, that 

 palatability is greatly influenced and controlled by familiarity and 

 habit with regard to food. 



Concerning the question of digestibility, in ome foods like hay 

 a)id straw the proportion of the various constituents digested is low, 

 whereas in the case of most of the cakes and meals practically all the 

 food constituents are digestible. In the method of rough commercial 

 comparative valuation given in this article the question of digestibility 

 is ignored, so the comparison should only be made between foods 

 which have approximately the same digestive coefficients for the 

 corresponding food constituents. For instance most of the different 

 brands of oilcakes might safely be compared in this way with one 

 another, for approximately the &ame proportion of each corresponding 

 food constituent would be digestible in all of tliem. As an example, 

 it is found in most cases of this particular class of foods that the 

 percentage of the total protein that is digested bv stock is roughly 

 the same. On the other hand, we could not compare in this way the 

 commercial value of a certain sami)le of hay witJi any of the oilcakes, 

 for instance, because the proportion of each food constituent digestible 

 is much lower in the former. 



Manurial Value of Foods. 



Another factor of importance in determining the relative values 

 of foods in their effect upon the quality and quantity of the resulting 

 manure obtained from the animals that are being fed on them. A' 

 foodstuff may thus be of considerable value to the farmer after it has 

 passed through the animal, yet the market price of a foodstuff often 

 bears no relation to its manurial value, the commercial value being 

 determined by its worth as a food simply and not as a manure in 

 addition. 



Oil or fat is one of the most costly constituents of a feeding stuff, 

 because, as previouslv mentioned, it is a source of far more energv in 



14 



