18 PRINCIPLES OF FEEDING FARM ANIMALS 
fiber in the feed. This method, which is known as the Weende method 
gives pure cellulose or woody fiber, with some impurities like pentosans, 
incrusting substances (lignin, cutin), and certain insoluble proteins. The 
method does not give very satisfactory results, and is only used for want 
of some better method of arriving at the amount of fiber present in feeding 
stuffs. 
e. Ash or mineral matter is obtained by igniting at a low red heat 2 
grams of the sample and weighing the residue after cooling in a desic- 
cator. The crude ash thus obtained generally contains some free carbon, as 
well as carbonates and sulfates formed by oxidation of organic components 
of plant materials. It is sometimes purified by treatment with distilled 
water, and the amount thus found is given as pure ash. 
f. Nitrogen-free extract is obtained by subtracting the sum of the 
percentages of the preceding components from 100. It includes chiefly 
starch, sugar, pentosans, and organic acids (p. 13). The amounts of the 
first three components are also sometimes determined separately by well- 
known methods of analysis that are of interest mainly to chemists.” 
The example given below will show the customary form of re- 
porting analyses of feeding stuffs. | a 
Chemical Analysis of Timothy Hay 
Per cent 
MOIStULG® ejects cinseg-onueans Seated ois ae emis aes oss sens 13.2 
Crude protein ...... Maite Ss bits oes eattoeredey A eke give 5.9 
Hat. fsa oi Sass 3 eee eee ss RU Sen Gea ees eee Erte ieee s 2.5 
RHO sess cactesstae panera SA eg PERE ON OS SES Se PERSE 29.0 
Nitrogen-free extract .......... 00. cee eee eee 45.0 
ABD since ee seers wueggrn iw aetieds sateen dental doen Haag Paset site 4.4 
100.0: 
QUESTIONS 
1. Name the elements essential to plant growth; also some others that 
are always present in plants. F —— 
. What are the groups of plant components.determined in ordinary chemical 
a alyses? fae * ae EVES aay Bete agar Feb Se 
Givethe main characteristics of each one of these components. 
. What is protein, nitrogen-free extract, carbohydrates? 
. State the difference in the chemical composition of these substances. 
; oe aie ordinary form of reporting a chemical analysis of a feeding 
stuff. 
ome po 
2 For complete directions for making chemical analyses of feediny 
stuffs and other agricultural products, see Official and Provisional Methods 
of Analysis, Association of Official Agricultural Chemists, Bureau of 
Chemistry, U. S. Department of Agriculture, Bulletin 107 (Revised), 
Washington, 1912. 
