CHAPTER XVIII. 



COMPOSITION OF PLANTS AND FEEDS. 



Feeding stuffs are divided into two great groups concentrates 

 and roughages. A concentrate, or concentrated feeding stuff, 

 consists of seeds, and various milling by-products. A concen- 

 trate is rich in protein or in nitrogen-free extract and contains 

 comparatively small amounts of crude fiber. As a general rule, 

 the crude fiber of a concentrated feed does not exceed 10 per 

 cent., though there are exceptions; crushed cottonseed cake, for 

 example, contains about 27 per cent. Examples of con- 

 centrates are corn, wheat, rice bran, cottonseed meal, gluten 

 meal, wheat bran, etc. 



A roughage is a feed containing relatively high percentages of 

 crude fiber and much smaller amounts of nitrogen-free extract 

 and protein. Further, the constituents of the nitrogen-free ex- 

 tract are less digestible and less valuable to the animal than those 

 of concentrates. 



Seeds. The seed contains an embryo plant with sufficient plant 

 food and organic matter to give the young plant a good start in 

 life. Seeds of agricultural importance may be divided into three 

 classes : 



(a) Starchy Seeds. Seeds of the cereals belong to this group. 



(b) Oily Seeds. Seeds of cotton, flax, hemp, sunflower, 

 mustard, etc., belong in this group. OH is manufactured from 

 them. 



(c) Seeds Rich in Protein. Seeds of peas, beans, and other 

 leguminous crops belong in this group. 



Other classes of seeds are known, but they are not of great 

 agricultural importance. 



Germination. In germination, the reserve material in the seed 

 is converted into soluble forms, conveyed into the growing plant, 

 and formed into new material. The chemistry of this change 

 depends to some extent upon conditions. The proteids are con- 

 verted into asparagin and other amido bodies, and the fat is 

 oxidized and changed to soluble materials, which are used by the 



