FOOD AND ITS RELATION TO HEALTH 



237 



Chemical Composition of Some Grouse Foods 



The various elements, compounds and organic substances that form the structure of a plant 

 or animal are the items that make up its nutritive character. To determine the amount of 

 each present a standard procedure is followed. First fresh samples of the food item to be ana- 

 lyzed are gathered. From it the moisture present is extracted by drying. Then the oven-dried 

 sample is chemically analyzed to measure the quantities of proteins, fats, fiber and ash or min- 

 eral matter. All these are expressed in terms of weight per 100 grams of the sample. The sum 

 of these is subtracted from 100 and the remainder, designated as "nitrogen-free extract"', is used 

 to represent the more digestible carbohydrates, in contrast with the crude fiber, which is large- 

 ly indigestible carbohvdrates. 



Such an analysis may be in itself extremely accurate. Because of the work involved, how- 

 ever, it is seldom completed in sufficient detail to present a full picture of food composition. 



TREMBLING 

 ASPEN 



g CHERRY 



O 



HORNBEAM 



Q. APPLE 



*" STACHORN 



SUMACH 



MOUNTAIN 

 LAUREL 



EVERGREEN 

 WOOD FERN 



30 40 50 60 70 



PERCENT OF COMPOSITION 



MINERAL 

 MATTER 



□ 



CRUDE 

 PROTEIN 



□CRUDE 

 FAT 



NITROGEN -FREE 

 EXTRACT 



□CRUDE 

 FIBER 



FIGURE 19. COMPOSITION OF EIGHT SPRING FOODS IMPORTANT TO GROUSE 



Nevertheless, it serves as a rough measure for establishing the amounts of these substances 

 present in each food. Accordingly, the chemical composition of a number of grouse foods 

 have been analyzed by the Investigation. The results are presented in lal>le 172 in the Appen- 

 dix. For the sake of completeness and comparison additional examinations selected from 

 published records but more or less applicable to New York conditions are also included. The 

 proportions of these constituents present in eight foods commonly eaten by grouse in spring 

 are shown in figure 19. 



One of these constituents, moisture, usually forms a larger part of a plant's structure than 

 does any other item. It may be defined as the amount of free water not incorporated in other 

 compounds. Its relation to health is discussed later in some details. 



Crude Protein 



This is the chemical compound most concerned with body building and feather develop- 

 ment. However, proteins differ markedly in their ability to meet the varied wants of the body 

 due to their fundamental differences in molecular structure. Dr. L. C. Norris of Cornell Uni- 

 versity, working with the Investigation from 1932 to 1935. found indications that grouse 

 chicks may thrive best on a starting diet containing from 27 to 30 per cent protein. This 



