INDUBHUSAN
CHATTERJEE
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not properly utilized, and since the straw is
highly unbalanced, it also behaves similarly
unless it is fed with more nutritious supplement.
Results have shown that weight for weight the
digestibility and energy efficacy of straw is liable
to be reduced to half, while protein metabolism
is severely upset when the straw is fed alone.
On the other hand the addition of cakes and
concentrates does not only arrest such a wasteful
process, but operates in a highly economic way
in stimulating maximum utilization of energy,
protein and other nutrients.
Varieties and strains of straw. According to
the statistics on crop report, the rice in Bengal
has been divided into three varieties, viz. amon
or winter rice, aus or autumn rice and boro or
spring or summer rice. In actual fact, although
amon mainly belongs to transplanted variety,
there are broadcasted and deep water varieties
also. The trials so far conducted in Bengal were
with the straw from transplanted amon, broad-
casted aus and transplanted boro. Time and
facilities were both limited to permit wide scale
work embracing all soil and climatic belts. From
the results so far obtained it appears that the
energy output of all straws is more or less similar,
but in many other respects each is markedly
different. Thus lime requirement which is general-
ly high under all kinds of rice straw feeding, is
comparatively less with amon, intermediate with
aus and highest with boro in which the quantity
of oxalic acid is also very high.
The earlier work was mainly done with straw
from Dacca and Nadia, and it was tacitly assumed
that the characteristic features of straw from differ-
ent soil belts would probably be the same. Thus
while lime, phosphorus and potash presented a
picture of complex metabolism, on feeding of
straws from other tracts, in the case of straws
from the saline belts of Barisal and Diamond
Harbour, it was found that other components
such as magnesia, soda and chlorine present
similar complexities. It has been further found
that in the amon varieties, the amount of oxalic
acid is lowest in Barisal straw, considerable in
Diamond Harbour straw and heaviest in Chin-
surah straw. The results suggest that (1) soil
condition and the environment exercise a pro-
found influence on general as well as some specific
characters of the straw grown in an area, and
(2) in order to get dependable results, feeding
and metabolic tests should be conducted with
local animals under local conditions of feeding.
It should be stated that so far the work was
done with mixed straws as were obtained from
the different localities, but comparison will be
more valid and helpful if such work is conducted
with straw of pure strains grown in the different
soil belts. Here it will be relevant to refer to
some experiments conducted with pure strains,
viz. indrasail and lattisail. The point of interest
lies in the fact that although chemical analyses
did not reveal any marked difference in their
composition, nutritional tests definitely established
the superiority of indrasail over lattisail straw.
Not only does it emphasize the need of conducting
work with other strains but also with strains
from typically different soil belts.
LIME ASSIMILATION UNDER RICE STRAW FEEDING
Rice straw contains an appreciable amount of
oxalic acid which has the property of keeping
lime in an insoluble form. This substance, which
in a soluble form is also a poison, has been also
found to vary according to soil and climate as
reflected in a high percentage in Chinsura straw
and lowest in Barisal straw. In the case of
boro variety of rice straw as well as in amon
variety of Chinsurah straw oxalic acid is found
in such a large quantity that it is theoretically
capable of rendering insoluble not only the entire
lime present in the straw but it is also potentially
able to render infructuous the efficacy of lime
from other food sources. A striking feature
however is that a large part of soluble oxalate
in the straw seems to undergo decomposition in
the rumen of cattle. By this, the directly harmful
effect of this substance is minimized but
the possibility of some direct absorption also
exists with its harmful effect. Apart from this
the presence of other (still unidentified) interfer-
ing substances against lime assimilation has also
been detected. A large amount of potash as
found in rice straw is another factor causing
disturbance in lime metabolism.
Both potassium and oxalic acid have loomed
large in the recent investigations with rice straw
feeding. As a matter of fact their effect on
metabolism is not merely of theoretical interest,
but has a far-reaching practical significance.
Evidences suggest that where oxalic acid is
present in large quantities, the potash content too
is high. The soluble oxalates exist chiefly as
potassium oxalate. In the rumen of cattle the
oxalate undergoes decomposition with the produc-
tion of carbonates and bicarbonates with which
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