CHAPTER III 
PRINCIPLES OF FEEDING 
Tur economic feeding of farm animals involves a knowledge 
of the principles underlying the practice. The better knowledge 
one has of the food, its source, use, composition, and digesti- 
bility, the more familiar one is with the function of the various 
food materials, and the balancing of rations, the more intelligently 
can one choose the foods that constitute the ration. 
FOOD 
Food may be defined as any material that an animal can take 
into its digestive organs and from which it can absorb matter for 
the nourishment of its own body. Plants and their products and 
by-products constitute the food of farm animals, although some 
farm animals are in part carnivorous, feeding on other animals 
or parts of animals. The plant during growth absorbs heat from 
the stn, which is held in latent form in the plant compounds. 
When these compounds are taken into the animal body and broken 
apart by digestion, some of this stored heat or energy is trans- 
ferred to the animal body. 
102. Use of food. — The matter and energy the animal collects 
from the food are put to three distinct uses: first, to support life; 
second, to reproduce life; and third, reserve supply stored up in 
some form. The animal must maintain its existence, and for this 
both energy and matter are required. A large part of the energy 
of the food goes to the maintenance of the body temperature. 
The body temperature of farm animals is considerably above that 
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