PRINCIPLES OF STOCK FEEDING 



49 



wool unless the food they receive con- 

 tains protein in sufficient quantities. 

 In addition to these functions, protein 

 serves also as a source of energy to ani- 

 mals and may also be used in the build- 

 ing of fat for storage in the body. 



Fiber and nitrogen-free extract — 

 The next two columns in the table of 

 analyses on page 47 show constituents 

 not found as such in the animal body. 

 These are fiber or crude fiber as it is gen- 

 erally given in tables of analyses and ni- 

 trogen-free extract. Crude fiber or cellu- 

 lose constitutes the essential part of the 

 cell structure or framework of plants and 

 seeds and gives to them their rigidity. 

 Under nitrogen-free extract is included 



Fig. 31 LUPINE. A WILD FORM 



COMMON IN THE WEST 



the starches, sugars, gum and like sub- 

 stances. Crude fiber and nitrogen-free 

 extract are referred to as a whole as car- 

 hohydraies. This term is very fre- 

 quently used in connection with feeding 

 stuffs and includes the whole group of 

 starches, sugars, fibers, cellulose and 

 gums, everything in fact except the pro- 

 tein, ash, crude fat and water. 



The carbohydrates are composed of 

 three elements only, carbon, oxygen and 

 hydrogen. The plants get all the car- 

 bon they need from the air and all the 

 oxygen and hydrogen necessary from 

 water. They are, therefore, the cheapest 

 constituents of feeding stuffs. Under 



the influence of the digestive fluids the 

 starches and crude fiber are converted 

 into sugar which is soluble and can be 

 readily absorbed into the animal system. 



Both fiber and nitrogen-free extract 

 serve as a source of energy and heat in 

 the animal body and for the production 

 of fat. The largest part of all farm crops 

 consists of these carbohydrates. Crude 

 fiber is especially abundant in the hays 

 and straws as will be seen by reference 

 to the table on another page, while the 

 starches predominate in such feeds as 

 corn, potatoes and cassava. Sugar is es- 

 pecially abundant in sugar beets and in 

 cane and sorghum. Digestible crude 

 fiber or cellulose is regarded at the pres- 

 ent time as being practically as valuable 

 for productive purposes as either starch 

 or sugar, leaving out of consideration 

 the work expended in preparing it for 

 use by the body. The work of chewing 

 and digesting crude fiber is, however, 

 very considerable. Kellner found that if 

 tarch be rated at 100, wheat straw would 

 have a value of 27, or practically be only 

 one-fourth as valuable as a food. 



Fat or ether extract — The last col- 

 umn of the table is designated as "fat." 

 In some tables of analyses of feeding 

 stuffs, it is called "crude fat" or "ether 

 extract." In analyzing feeding stuffs 

 they are extracted for a long time with 

 ether. The ether dissolves out not only 

 the vegetable oil or fat proper, but also 

 certain waxes, the green coloring mate- 

 rial of the plant, etc. This crude fat, 

 therefore, is a mixture of a number cf 

 different substances. 



The fat of foods serves for the pro- 

 duction of energy and heat in animals 

 the same as the carbohydrates do, and 

 may also be modified and deposited as 

 animal fat. For these purposes fat is 

 considered to be about 2.25 times as val- 

 uable as carbohydrates. Like the car- 

 bohydrates the fats contain just the 

 three elements — carbon, oxygen and hy- 

 drogen. The fat molecule, however, is 

 much more complex than the carbohy- 

 drate molecule. 



The fat content of green plants 

 is usually very low, as may be seen from 

 the table, and consists very largely of the 

 waxes and green coloring material which 

 have a lower feeding value than the 

 true fats. True fat is found mostly in 

 the seeds of plants. Corn and oats con- 

 tain about 5 per cent of fat, while cot- 

 ton seed contains as much as 20 per 

 cent. 



