16 PRINCIPLES OF FEEDING FARM ANIMALS 
by special ferments in the intestinal tract of herbivorous animals. 
By this decomposition marsh gas and other gases are formed, and 
also organic acids, like acetie and butyric acids. Since straw is very 
high in fiber, and ruminants, like steers, sheep, and goats, can sub- 
sist for a long time on coarse straw only, we are justified in con- 
cluding that this substance possesses a certain nutritive value, 
although authorities differ as to how much value shall be ascribed 
to the digestible portion of cellulose. ; 
Plants increase in their contents of fiber toward maturity as the 
‘stems become coarse and tough; hence their digestibility decreases 
during the latter stages of plant growth (p. 58). The following 
approximate amounts of fiber are found in different classes of 
feeding stuffs: 
Buckwheat hulls, buckwheat straw, and flax shives, 45 per cent; — 
straw of cereals, 40 per cent; hay from different grasses or legumes, 
20 to 35 per cent ; cereals, 0.2 per cent (rice) to 10.8 per cent (oats) ; 
roots and tubers, 0.4 to 2.2 per cent; concentrated feeds, 0.9 to 30 
per cent, generally, however, less than 20 per cent (Fig. 4)... 
A high fiber content indicates that a feed is of relatively low 
value for stock feeding, and vice versa. The figures for this com- 
ponent, with those for protein and fat, are, therefore, of the great- 
est assistance to feed buyers in judging the value of manufactured 
and other feeds. hac 
Chemical Analyses of Feeding Stuffs.—The following com- 
ponents are determined by the chemist in the.ordinary analysis of 
feeding stuffs: Water (often called moisture), protein, fat, fiber, 
and ash; the difference between 100 and the sum of percentages 
of these various components obtained in the analysis is known as 
nitrogen-free extract (starch, sugar, pentosans, organic acids, etc.). 
Methods of Chemical Analysis.—The outline of the common method 
adopted in chemical laboratories in the analysis of feeding stuffs given below 
will be of value to students by enabling them to better understand data 
and discussions relating to the chemical composition of feeding stuffs 
(Fig. 5). —— 
a. Moisture (water) is detertiined’ by heating a small portion (gener- 
ally 2 grams)* of the’ tarefully-simpled and finely-divided feeding stuff 
in a steam-bath'or water oven at 100° C. for two to five hours, till it no 
longer loses weight. After cooling in a desiccator, it is weighed carefully 
on a chemical balance and the percentage loss calculated on the original 
weight is taken to represent moisture. Volatile organic substances somie- 
times present in minute amounts,in plant materials would also te in- 
cluded in this loss. In the case of, some feeding stuffs containing fats that 
take up oxygen, as corn. flaxsedd,'Hnd'other oil-bearing seeds, the material 
must be heated. in a current ‘ofshytregen or other inert gas, so as to 
prevent, oxidation, and a resulting. increase in weight during the drying, 
which would give too low a moisture content. 
tz. of an ounce. 1 ounce equals 28.35 grams. 
