262 
Journal of Agricultural Research 
Vol. XXVII, No. s 
pounds, the digestible crude fiber from 349 pounds to 732 pounds, and 
the digestible nitrogen-free extract from 390 pounds to 622 pounds. The 
digestibility of the pentosans, which are distributed between the fiber 
and nitrogen-free extract, was increased from 287 pounds per ton to 605 
pounds. In short, the feeding value of the oat hulls was about doubled. 
It seems that such a result should warrant further investigation with the 
idea of making the process of economic importance. 
SUMMARY 
This paper reports the results of an investigation on the problem of 
increasing the digestibility and feeding value of grain hulls. 
A review of the literature shows: 
1. That the important constituent of the cereal and other straws is lignocellulose, 
a compound the chemistry of which is not fully understood. It is known, however, 
that it consists of cellulose linked in some manner with lignin and that the presence 
of the latter compound is characterized by the splitting off of methoxy (CH 3 . 0 ) groups 
upon hydrolysis. 
2. That the action of dilute alkali on fiber is threefold, consisting of separation of 
the silicic acid which forms a part of the incrusting material, splitting off of the me¬ 
thoxy groups of the lignin with formation of acetic acid, and springing of the bonds 
which exist between the lignin and cellulose. 
3. That practically all of the work on this problem has been carried on in Germany, 
most of it since the commencement of the World War, and the material most generally 
investigated has been straw, the digestibility of which has been decidedly increased. 
Grain hulls do not appear to have been worked with heretofore. 
In our investigation the method used for treatment of the hulls was 
that of Beckmann. The materials treated were oat hulls, barley hulls, 
rice hulls, cottonseed hulls, and flax shives. The hydrolyzing agent was 
cold dilute sodium hydroxid, the strengths employed being 1, 1.5, and 3 
per cent. 
Most satisfactory results were obtained with NaOH of 1.5 per cent 
strength; 1 per cent was apparently too dilute, and 3 per cent in the one 
instance used did not have sufficient increased action over the 1.5 per 
cent to warrant its use. 
The effect of the alkali on the composition of the hulls was ascertained 
by the usual methods of fodder analysis, supplemented by determination 
of some of the ultimate constituents of the hulls both before and after 
treatment. 
The result of treatment was a decrease in all proximate constituents 
except the crude fiber, which from an absolute standpoint remained 
practically the same but relatively was considerably increased. 
Losses in weight due to the treatment were noticed in all materials; 
they were greatest in the case of the flax shives (25 per cent), and least 
in the case of the cottonseed hulls (9.7 per cent). 
The effect of the alkali on the digestibility of the hulls was ascertained 
by the usual methods employed in digestion experiments, sheep being 
the animals used. As a result of the treatment with 1.5 per cent NaOH 
the digestibility of the important constituents of oat hulls and barley 
hulls was markedly increased, the feeding value of the oat hulls being 
doubled. The digestibility of rice hulls was also improved greatly, but 
not sufficiently to be of economic significance. The results with cotton¬ 
seed hulls and flax shives were in the main negative. 
Since the digestibility of oat and barley hulls is greatly improved by 
the action of dilute alkali, some method should be devised that could be 
applied on an economic scale. Also, a method for the improvement of 
the digestibility of cottonseed hulls is worthy of further attention. 
