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The Nutritive Value of Alkali-treated Cereal Straws
Thus the clinical symptoms of diuresis induced under the paddy straw feed-
ing has been attributed to the high potassium content of the straw. To
counteract the possible ' washing out' effect of potassium on sodium and
chlorine, a routine feeding of a comparatively higher dose of common salt
supplement has been found necessary. The high potassium content may
also be responsible, as has been found in the present investigation, for the
wastage via the kidney of a significant quantity of nitrogen, which would
otherwise have been retained in the body. In support of this observation
the experimental evidence suppli ed by Richards, Godden and Husband
[1927] can be cited. These workers have shown that excessive potassium in
a ration decreases both the assimilation and retention of nitrogen. High
potassium ingestion has further been proved by these workers to depress the
absorption of calcium. Perhaps a part of the chronic negative balance under
paddy straw feeding can be explained on this basis. The present investiga-
tion definitely shows that the alkali treatment removes a large portion,
practically two-thirds, of this undesirably high amount of potassium from
the paddy straw.
The large oxalate content is another peculiarity of paddy straw. Evi-
dence has been collected in this laboratory to the effect that a major portion
of this oxalate is in the form of soluble potassium oxalate but a significant
fraction is present as insoluble calcium oxalate. The soluble oxalate fraction
has been found to be physiologically harmless. On the other hand, a major
part of the insoluble calcium oxalate passes out as such in the faeces without
apparently entering into any metabolic reaction in the body. The insoluble
fraction of oxalate in paddy straw thus prevents the animal from making
use of a significant portion of ingested calcium.
On alkali treatment of the paddy straw, a considerable portion of the
total oxalate is washed out. An interesting effect of the treatment was that
the percentage of insoluble calcium oxalate in the straw was considerably
increased owing to the interaction of the calcium of the wash water and the
soluble oxalate of the straw. As a result, the actual ingestion of calcium as
unabsorbable calcium oxalate increased on an average from 4.2 gm. in period
3 to 7.4 gm. in period 4 per animal per day. Since the total intake of calcium
in both the periods was the same this meant that the amount of the available
calcium was apparently less in period 4 than in period 3. In spite of this,
there was a better absorption and retention of this mineral during period 4.
This is believed to be partly due to the removal of the excess potassium
from the straw.
Alkali-treated straw as a feed for horses
In a recent review on the alkali treatment of straws, Williamson [1941]
has drawn attention to the poor quality of hay usually available in India for
feeding horses in the Remount Depots. He has raised the question as to
whether an economic method such as alkali treatment could not be utilized
to improve the quality of the average hay available in the country. In feed-
ing a roughage to horses, cereal straws (with the possible exception of oat
straw) are usually avoided because of their general coarseness and poor nutri-
tive value. However, by alkali treatment, not only can the nutritive value
of straws be improved but, as has been mentioned earlier, the treated straws