88
Calcium Supplement on the Digestion of Organic Nutrients
TABLE IV
Mean digestibility of Boro straw (Obtained by the method of elimination)
Particulars
Dry Matter
. . . .
Organic matter
Crude protein
True protein
Ether-extract
Crude
fibre
.
.
.
N. F. extract
No. Lime
41.27
51.33
44.53
31.74
32.55
63.71
45.86
Lime
39.00
47.89
44.07
30.61
16.52
56.45
44.93
The results of Tables III and IV first require to be compared amongst themselves and then with
those of Tables I and II. Judged, whether on the basis of combined digestibilities (Table III) or
on the digestibilities of straw components (Table IV), lime feeding has definitely depressed the digesti-
bility of organic matter mainly from the share of ether-extract and crude fibre.
It should be noted also that unlike under Napier silage (Table I) the addition of lime supplement
under Boro has not contributed in any way towards a better lime assimilation; but the effect has
been well reflected in depressing the digestibility of both ether-extract and crude fibre.
In so far as ether extract is concerned,—lime feeding has been followed by a lowered digestibility,
under both Napier grass and Boro straw. This is also in conformity with what might be expected
since the presence of lime offers the possibility of formation of insoluble calcium soap which eli-
minates out with the faces as undigested matter thereby reducing the quota of digested share.
In the case of fibre however the caustic action of lime is likely to reduce the resistance of the
tough integuments of the fibre thereby helping in a better digestion. This has happened also with
Napier silage, but not only has it failed under Boro straw with lime but there has even been a de-
pression in its digestibility. This is difficult to explain.
Here it is worthy of note, as already stated, that under Napier silage the balance under lime
feeding has been either positive or very slightly negative. On the other hand Boro straw has exhi-
bited a negative lime balance which is almost identical under both 'Lime' and 'No lime' The
only other difference between them is that Napier silage was fed with what was supplied as linseed
cake, whereas Boro straw was fed with mustard cake. But the main reason for which lime assi-
milation in Boro straw has been very poor, is due to the fact that this straw contains a very large
percentage of oxalic acid.
SUMMARY
Two feeds of which one (viz. Napier silage) was deficient in lime and the other (viz. Boro rice
straw) had a tendency of poor lime assimilation, were fed to bullocks with and without supplement
of calcium as CaCO 3 . It was found that amongst the organic nutrients ether-extract was most suscep-
tible to a lowered digestibility. The fibre fraction was also found to be affected but the results
were not identical since under Napier feeding the addition of lime supplement effected an increase
in its digestibility, but under Boro straw it was lowered. It may be stated that in the case of
Napier silage the addition of lime definitely contributed towards a better lime assimilation and fibre
has been better digested under 'Lime' combination. If this is ascribed to the better effect of
lime, there is no reason why it should have been different under Boro straw feeding under similar
combination with lime. In the case of ether extract the presence of lime offers the possibility
of the formation calcium soap thus holding out lime. This might account for the depressed
digestibility found in the ether-extracts of both Napier silage and Boro straw, but we have at
present no explanation as to why the fibre digestibility under silmilar lime combination was increased
under Napier feeding and lowered and Boro straw feeding.
It is also necessary to state that the poor lime assimilation under Boro straw feeding is associated
with a large percentage of oxalic acid in it.
REFERENCES
Chatterjee, I and Sarkar, S. N. (1940). Indian J. vet. Sci. 17, 88
Henry, K, M., Kon., S. K. and Thompson, S. Y. (1940). Chem. J. 34, 998
Ranganathan, V. and Ray, V. V. S. (1938). Nature 142, 165
Swaminathan, M. (1939). Ind. J. Med. Res. 27, 147
Woodman, H. E. and Evans (1930). J. agr. Sci. 28, 587