Feb. 2,1924 
Digestibility of Tested Grain Hulls 
257 
materials being so insoluble that it was unattacked by the alkali, while a 
portion of the more soluble organic constituents was removed. It is 
possible also that sufficient residual soda remained combined in these 
materials to account for the ash increase. 
The striking feature of the results is the appreciable percentage increase 
of fiber in all cases, due to the removal of the more soluble portions of 
the hulls. One notices also that the increase in fiber was consistently 
greater the higher the concentration of sodium hydroxid. Although 
the protein and fat suffered considerable loss, they are present in relatively 
small percentages and hence are of minor importance. (See Table IV.) 
Table IV. —Net loss in pounds on a dry-matter basis of each proximate constituent 
I,oss in pounds for each 100 pounds of dry matter 
treated. 
Material. 
Total 
ash. 
Crude 
protein. 
Crude 
fiber. 
N-free 
extract. 
Crude 
fat. 
Total. 
Oat hulls, treated i per cent NaOH. 
x. 26 
0.43 
2.18 
6-37 
0.51 
10. 75 
Oat hulls, treated 1.5 per cent NaOH. 
1-97 
1.12 
a.31 
13-30 
•47 
16.55 
Barley hulls, treated 1 per cent NaOH. 
.68 
2.41 
■25 
15-31 
.66 
19-31 
Barley hulls, treated 1.5 per cent NaOH. 
1.05 
3-44 
•39 
14 - 73 
.68 
20.29 
Rice hulls, treated 1.5 per cent NaOH. 
4-32 
.90 
2. 91 
7- 18 
. 26 
15 - 57 
Rice hulls, treated 3 per cent NaOH. 
8.49 
1-55 
1-35 
7.83 
•31 
19 - 53 
Cottonseed hulls, treated 1.5 per cent NaOH. 
35 
1-34 
a 1.01 
9-27 
•43 
9. 68 
Flax shives, treated 1.5 per cent NaOH. 
.08 
I- 93 
6. 70 
15-51 
.81 
25-03 
a These figures represent gain instead of loss. In the case of the crude fiber an absolute gain is im possible, 
so these small increases are explainable only on the basis of analytical or experimental error. In the case 
of the ash which showed an absolute increase it is possible that residual NaOH might account for it. 
Considering the results from this angle, we see that the fiber was practi¬ 
cally unattacked in so far as its removal by solution was concerned, 
while the greater or lesser amounts of all the other constituents were 
removed. The greatest actual losses were in the case of the nitrogen- 
free extract, which includes the starch, a portion of the pentosans and 
lignin, and allied substances. 
EFFECT OF THE TREATMENT ON SOME OF THE ULTIMATE CONSTITUENTS OF THE HULLS 
It was thought that a more detailed analytical examination of the hulls 
than that involved in the conventional fodder analyses would furnish 
still more accurate information as to the chemistry involved in the 
process. Table V gives the results of starch, pentosan, and lignin 
determinations made as described in a previous section of this paper. 
The figures in Table V show that relatively the starch was increased 
in all instances, the pentosans in all but one instance, and the lignin in 
five out of eight. In a general way, the increases in pentosans and lignin 
parallel those for fiber, which is what would be expected. 
One is impressed with the high percentage of pentosans in the un¬ 
treated oat hulls; in fact, pentosans together with the lignin make up 
the major portion of the hulls. The rice hulls are composed largely of 
ash, fiber, including pentosans, and lignin. They are somewhat more 
lignified than the oat hulls, and the presence of the lignin together with 
the high ash percentage accounts for their inferior nutritive value. 
Cottonseed hulls with their very high crude fiber percentage, together 
with the large amount of pentosans and lignin, are in the same class 
with the rice hulls. Flax shives, containing approximately 54 P er cent 
