6 PRINCIPLES OF FEEDING FARM ANIMALS 



whose exact composition has not yet been ascertained. For our 

 present purpose they may, however, be conveniently considered as 

 belonging to a few groups of substances which can be readily deter- 

 mined by chemists. These groups of components are separated in 

 the customary chemical analysis of feeding stuffs, and the per- 

 centage quantities present in each are ascertained. For the pur- 

 poses of chemical analysis and for our discussions we may thus 

 consider plant materials composed of 



I. Water. 



II. Dry substance. 



The dry substance of plants is of either (1) mineral or (2) so- 

 called organic origin. The former components are known as 

 mineral matter or ash; while the organic matter is composed of 

 the following groups of substances : Protein, fat, nitrogen-free 

 extract, and fiber. The last two belong to a group of substances 

 known as carbohydrates. 



The schedule given below will help to make clear these various 

 groups of plant components : 



Plants contain Composed of the elements 



I. Water Oxygen, hydrogen. 



! Potassium, sodium, calcium, 

 magnesium, sulfur chlo- 

 nn, iron, phosphorus, 

 silicon, etc. 



( Carbon, oxygen, hydrogen, 



2. Protein 1 nitrogen, sulfur (and 



I sometimes phosphorus). 



3. Fat ] 



4. Nitrogen-free extract [ Carbon, oxygen, hydrogen. 



5. Fiber.. .' J 



, COMPOSITION OF PLANTS 



Water is found in all plants and plant materials, ranging in 

 amount from 5 per cent to 95 per cent in extreme cases. Some 

 factory by-products which have been artificially dried contain less 

 than 10 per cent, in some cases as low as 5 per cent of water. Hay 

 and dry coarse feeds generally contain from 10 to 20 per cent, 

 while corn fodder (stover) and some kinds of hay, as alfalfa, will 

 occasionally contain as much as 30 per cent of water when im- 

 perfectly cured or exposed to damp or rainy weather. The cereals 

 and most concentrated feeds contain about 12 per cent water; 

 green forage crops from 70 to 90 per cent ; silage, 70 to 80 per 



