Fertilizers and Feeding Stuffs. 379 



fullowing constitueuts : — Protein, fibre, moisture, mid ash, tlie per- 

 centage of soluble carbohydrates being calculated by finding- tlie 

 difference between 100 and tlie total of the other percentages. 



The moisture in feeding stuffs varies considerably, being as low as 

 8 or 9 per cent, in oil cakes and as high as 90 per cent, in roots. In 

 the case of artificial foods it is better that the amount of water should 

 be low, in order that the proportion of food constituents be corre- 

 spondingly higher, for it is unnecessary and uneconomical to pay 

 carriage on water in a foodstuff. 



The ash is the mitiera' portion left after igniting the material in 

 the open air until all the volatile and organic matter has disappeared. 

 This mineral matter, although no money value is attached to it com- 

 mercially, is an essential constituent in food, for it is necessary for 

 the building up and the repairing of the skeleton and the various 

 tissues of the body, and also for the proper performance of the diges- 

 tive, respirative, and circulatory processes. Young r ninials especially 

 are liable to suft'er in development should their food be deficient in 

 mineral constituents, and it A-ery often becomes iiecessary to supple- 

 ment their ordinary food with a ration of such mineral substances as 

 bone meal and common salt. 



The crude fi.hie is mainly made up of cellulose, one of the carbo- 

 hydrates, and is usually regarded as being the portion of the food 

 that would resist digestion if fed to an animal, and is therefore not 

 given a value from a commercial point of view. Although it is not 

 absorbed to any appreciable extent into the animal system it is a 

 mistake to think that the crude fibre has no digestive value and is 

 unnecessary in the animal's diet. During the process of digestion it 

 is necessary that the digestive organs should be comifortably full in 

 order to promote the desired movements of the organs and of the food 

 contained therein. There must therefore be a large propoition of 

 i]idigestible matter present, besides the digestible portion, in order to 

 make up the necessary bulk. 



The soluble caihohijdrates comprise the sugars, starches, gums, 

 and similar compounds. They are all composed of the element 

 carbon, hydrogen, and oxygen. Tn the animal system they are 

 oxidized and converted ultimately into water and carbon dioxide 

 (carbonic acid gas), at the same time generating heat and other forms 

 of energy in the animal body. 



The fats and oils also comprise the same elements as the carbo- 

 liydrates and have the same functions to perform Jn the body. Their 

 power in this respect is nearly two and a half times that of the carbo- 

 hydrates and are consequently so much more valuable as food con- 

 stituents. 



The pi'oteins or albuminoids contaivi besides the above-mentioned 

 elements nitrogen, sulphur, and ])hosphorus. The typical protein is 

 albumen, of which the "white'' of an egg is altogether composed; 

 the glutens are also proteins and are i)resent in the seeds of the 

 different cereals. With the exception of the mineral portion of the 

 skeleton and the layers of fat in the body practically all the other 

 tissues are composed of proteins. 



Food Unit.^. 



For the purpose of the commercial valuation of a farm food it is 

 alwa\-^ assumed that it is only the proteins, fats, and soluble carbo- 

 liydratrs that have a monetary value, and by adopting the same 



