- POUWULTRIY-CRAFT. 109 
CHAPTER VIII. 
Science in Poultry Feeding. 
148. Where Common Knowledge Fails.— Purely practical knowledge 
and skill, enough for ordinary use, can be acquired without study of the 
science of feeding. The simple instruction which helps to a common sense 
understanding of the needs of an animal organism and plain knowledge of 
the properties of the staple poultry foods, is enough for most poultry keepers 
— enough for all as long as only familiar articles are used in approved combi- 
nations. But when it is advisable to use other articles or untested combina- 
tions, this common knowledge fails. It has not equipped the feeder to work 
out feeding problems for himself. Work at them he may, through a tiresome 
and expensive course of haphazard experiments, but there is no need that he 
should follow such a course. An elementary knowledge of the science of 
feeding, and access to a table giving the analyses of the food stuffs he wishes 
to use, make it possible for him to formulate rations with absolute certainty 
as to their theoretic value, and reasonable expectation of their practical feeding 
value. 
149. Food Requirements of Fowls.— The food which a fowl eats has 
three functions: (1). To develop and maintain its organic structure; (2). To 
keep it warm — to keep up heat zz the body; (3). To furnish the strength — 
energy — which is expended in every movement. The chemical elements 
which maintain these functions are found in combination in every article of 
food, constituting its digestible matter; in the staple grains they occur in 
nearly the proportions required by fowls under average normal conditions. 
150. Food Elements may be classed as: Przncifal and Subordinate. 
PRINCIPAL Foop ELEMENTs are: 
(1). Protedds (or protein) albuminous, or nitrogenous matter; in grains, 
gluten; in milk, casein; in meat and blood, fibrin; in bones, gelatin. Pro- 
tein is the nourishing matter, supplying material for bone, muscle, blood, 
feathers, eggs. 
