178 POULTRY CULTURE 



obtained in a greater variety of forms, but the variety of minor food elements is 

 much greater, including small quantities of many elements not secured when the 

 birds eat only such food as man may profitably provide for them. The function 

 of these minor elements in nutrition is little understood. The fact that our 

 domestic animals and birds thrive better on a ration which gives them a variety 

 of those elements or essences characteristic of different organisms that are about 

 equal in the value of their principal nutrients, suggests that they have functions 

 of great importance in nutrition, although, in the present state of knowledge of 

 the subject, they cannot be included in food calculations based on the chemical 

 constituents of food articles. Again, the fact that certain foods are evidently 

 better foods for certain animals than other foods almost identical in the pro- 

 portions of their principal nutrients indicates that the peculiar value of these 

 foods is either in their form or in the form in which the principal nutrients 

 appear in them, or in some of the minor elements. 



Common poultry foods. In every place those foods (used by man 

 for himself or his larger domestic animals) which can be fed to 

 poultry most economically are the poultry foods in general use. In 

 any section the grain that is most abundant and cheapest is likely 

 to be the principal food of the poultry of that section. Throughout 

 the greater part of the United States corn is the principal grain fed 

 to poultry, but in wheat-growing sections wheat may be cheaper. In 

 Japan rice is the principal grain fed to poultry. By-products of all 

 kinds of food preparations form an increasingly important part of 

 the common poultry foods. In a sense the greater part of all food 

 used by poultry is waste product or by-product. The wheat, oats, 

 barley, or other grain fed to poultry is usually of inferior grade, 

 damaged, or, if of choice quality, only temporarily available because 

 of an oversupply bringing the price to a point where it can be 

 profitably fed to stock. Even of corn, which is produced in such 

 enormous quantities, a large proportion of what is sold for stock 

 feeding is of poor quality. As a result of modern methods of pre- 

 paring and handling foodstuffs for man, by-products of mills and 

 packing houses, in great number and quantity, are placed on the 

 market for stock feeding. The profitable use of these requires some 

 knowledge of the composition and feeding properties and values 

 of foods. 



Composition of foods. Nutritive elements in foods are proteids, 

 carbohydrates, fats, and ash (mineral matter). All foodstuffs also 

 contain fiber and water, the proportions of these varying widely 



