74 The Feeding of Animals 



ering feeding stuffs as a whole, we find that hays, and 

 especially straws, are rich in crude fiber, while tubers, 

 roots and the grains contain only small amounts. In 

 certain by-product grain foods, like bran, which is made 

 up mostly of the seed -coatings, fiber is present in fairly 

 large proportions, while in other materials like gluten 

 meal, which are derived from the inner parts of the 

 grain, the percentages are very small. 



The stage of growth at which a plant is used for 

 fodder purposes has a marked influence upon the pro- 

 portion of crude fiber. In young, actively growing vege- 

 table tissue, the cell -walls are thin, but as the plant in- 

 creases in age, these thicken, chiefly through the depo- 

 sition of cellulose. Pasture grass has less cellulose than 

 hay, and early cut grass less than that which is ripe. 

 In general, the toughness and hardness of mature plants, 

 as compared with young, is due to the increased pro- 

 portion of woody fiber, although the decrease in the 

 relative amount of water in the tissues and the deposi- 

 tion of other substances have more or less effect. 



NITROGEN -FREE EXTRACT 



This name, like protein, is a collective term, being 

 used to designate a group of compounds possessing 

 certain characteristics in common. A great variety of 

 substances are included under this head, many of which 

 are among the most familiar objects of every -day life. 

 Here we find the starches, sugars, gums and vegetable 

 acids, compounds universally used, and which even chil- 

 dren recognize by name. Certain of these non-nitrog- 



