THE COMPOSITION OF FEEDING STUFFS 13 
Fat contains more carbon and less hydrogen than the group 
known as carbohydrates, viz., on the average, 
CATON essisvsntediecwitsenen ty ‘76 per cent 
Hydrogen, ............ 12 per cent 
ORY PONS aes ec Sees 11.5 per cent 
They, therefore, furnish more energy on combustion and are 
more valuable as heat- “producing substances than are the carbo- 
hydrates (for which see below). 
Nitrogen-free extract is a general name for all non-nitrogenous 
organic substances in plants and plant materials besides fat and 
fiber. It includes a large number of substances of different proper- 
ties and value for feeding purposes, such as starch, sugar, pentosans, 
pectin, organic acids, and other compounds that are present in 
plants in small amounts and are of minor importance. The name 
“ nitrogen-free extract ” is in reality a misnomer, as but few of the 
substances included under this group name are soluble in water or 
other liquids ; it has come into general use, however, since the early 
days of agricultural chemical analysis, and no better name for this 
group of substances has so far been suggested. 
Carbohydrates.—The nitrogen-free extract and fiber form the 
group called carbohydrates. These include substances widely dis- 
tributed in plants and of the greatest importance to the feeder. 
They are, in general, characterized by the fact that they contain the . 
elements carbon, oxygen, and hydrogen, the latter two being present 
in the same ratio as in water, one molecule of which contains two 
atoms of hydrogen and one atom of oxygen (H,0). The more im- 
portant substances of this group are briefly considered below. 
Starch is one of the first organic substances formed in the living 
plant from the carbon-dioxide of the air and water. It is changed to 
sugar in the transfer of carbohydrates from one part of the plant 
to another, and accumulates as such in large quantities as reserve 
material in some plants, as the beet root and sugar cane. In others 
it is changed into oil or fat, as in the so-called oil-bearing seeds, 
flax, sunflower, castor bean, etc. In still others, which most fre- 
quently happens, there is an accumulation of starch in the seeds, 
as in the case of the cereals and legumes. 
On boiling with dilute acid or through the action of diastatic 
ferments (diastase, ptyalin, etc.), starch is changed to sugar. This 
process forms the basis for the manufacture of corn or glucose syrup 
from Indian corn. 
