THE COMPOSITION OF FEEDING STUFFS 15 
pentosans are widely distributed in plants, and make up a consider- 
able proportion of the nitrogen-free extract of many plants. Hay 
from grasses contains about 20 per cent of pentosans; gluten feed, 
17 per cent; dried brewers’ grains and wheat bran, 24 per cent; 
clover, 10 per cent; cereal straw, 22 per cent; oil meal and dried 
distillers’ grains, 13 per cent. 
The best known substances of this group are araban, found in 
beet pulp, cherrygum, etc., and xylan or wood gum, found in wood 
and straw. 
The pectin bodies occur especially in unripe fruits; these sub- 
stances are responsible for the jellying of fruit juices, which de- 
pends upon pectin taking up water during the boiling of the fruit, 
0 5 10 S 20 2 30S SO 
COTTON-SEED HULLS 
‘BUCKWHEAT HULLS 
OAT STRAW 
OAT HULLS 
CORN COBS 
TIMOTHY HAY 
CLOVER HAY 
CORN STALKS 
ORIEO BREWERS” GRAINS 
OATS 
WHEAT BRAN 
GLUTEN FEED 
WHEAT MIDOLINGS 
BARLEY 
INDIAN CORN 
Fia, 4.—Fiber in plant materials, in per cent. 
gelatinous substances being formed known as pectoses or pectic 
acids. The mucilaginous substances of flaxseed and seeds or roots 
of some other ‘plants belong to this group; these substances do not, 
however, possess the importance that is attached to the preceding 
three groups of compounds, starch, sugar and pentosans. 
Fiber (called crude fiber or woody fiber “by some: authors) 
makes up the cell walls of the plants and is largely composed of 
cellulose. So-called incrusting substances (lignin and cutin) are 
always present, ‘especially in tough, woody plant materials, like 
husk, hulls, seed-coats, overripe hay and straw, which contain con- 
siderable proportions of these substances in the fiber. Fiber is more 
resistant to the action of solvents and digestive fluids than other 
groups of plant materials. It is attacked by bacteria and possibly 
vAstho vet 
