STOCK FEEDING 293 



Sugar is the soluble form of carbohydrates which circulates 

 in plants and is immediately available as plant food. When the 

 plant manufactures more food than is needed, the surplus is stored 

 up in the form of starch. When this reserve stock of food is needed, 

 some of it is changed back into sugar by the help of a ferment known 

 as diastase. On account of their solubility the sugars are digested 

 with ease. The principal kinds of sugar are cane sugar, derived 

 from sugar cane, sorghum, and sugar beets, grape sugar from 

 starch, fruit sugar from fruits and honey, malt sugar from malted 

 grain, and milk sugar from cow milk. The amount of sugar in 

 ordinary foodstuffs is small, but large amounts of it are formed 

 from starch and other carbohydrates in the process of digestion. 



The gums are not important as food compounds, and only a 

 small amount of them is found in plants used for stock feeding. 



Pentose. Besides the starch and cellulose there is another 

 group of carbohydrates known as pectin bodies, which give to 

 fruit their power of forming jellies when boiled, and they are con- 

 verted into a special kind of sugar known as pentose when digested. 

 Little is known of their exact chemical nature. 



Mineral Matter. In addition to the foods just mentioned there 

 are certain mineral matters needed by animals, but practically all 

 these are found in ordinary fodders in sufficient quantities for their 

 immediate needs. Some of the common minerals found in combi- 

 nations in the body are salt, lime, soda, and potash. Iron, phos- 

 phorus, magnesia, and a few other minerals occur in small and 

 varying proportions. Mineral salts enter into the composition of 

 the brain cartilage, and bone, and thus play an important part in 

 the structure of the body. 



The amount of ash or mineral matter in a plant is determined 

 by carefully burning a known amount of the substance over a slow, 

 steady fire long enough to drive off all the organic vegetable matter. 

 The weight of the residue gives the amount of mineral matter pr 

 crude ash. 



Value of Food. It is evident that only a part of the food eaten 

 by animals is retained and assimilated by their bodies and the 

 remainder passes off as manure. If an analysis of the food is made 

 and also one of the manure to determine the amount of nutrients 

 remaining, it becomes an easy and simple matter to calculate the 



