K. C. SEN, S. C. RAY AND S. K. TALAPATRA 293
straw (period 6). (b) It may profitably be utilized for production purposes,
such as work, lactation and growth. In order to make adequate provision
for S. E. in the production ration, it is necessary to include costly energy-
rich feeding-stuffs such as grains and seeds. These feeding-stuffs also con-
tain a certain amount of digestible protein. Very often this digestible pro-
tein may be considered an inevitable excess in the computed ration and
without specific use. As such, if energy moiety is the primary concern in
the adjustment of a balanced ration, this can as well be supplied by the
treated straw, which would be cheaper than the grain.
(d) The digestibility of protein and nitrogen metabolism.—During the
treated straw feeding, the digestibility of crude protein of the whole ration
showed a slight but definite depression. This depression may have been
due to the widening of the nutritive ratio as a result of better digestion and
utilization of the total carbohydrates. The interesting feature in the protein
metabolism of the animals under the treated straw feeding is the marked
drop in the nitrogen excretion in the urine with a consequent rise in the
nitrogen retention. The obvious higher biological value of the ingested
protein in periods 2 and 4 may have been due to (a) the removal of dele-
terious influences present in the original straw which affected the utilization
of protein, (b) a more congenial supplementary effect of the proteins from
the food. Either or both results were apparently brought about by the alkali
treatment of the straws. The higher retention of nitrogen may also have
been a consequence of an increased intake of energy from the treated straw.
The energy received from the rations in periods 1 and 3 was just sufficient
for maintenance, while the digestible protein given was comparatively high.
This higher intake of digestible protein was not perhaps utilized for the pro-
portionately lower supply of energy in periods 1 and 3 and as a result a large
portion of the absorbed nitrogen was probably simply deaminated and thrown
out in the urine. But as soon as the energy intake increased under the treated
straw-feeding, the nitrogen, which had previously been thrown out in the
urine, was retained to induce either growth or fattening or both. These
possibilities, in fact, were indicated by the increased gain in weight by the
animals in periods 2 and 4.
Whatever the reasons may be for the increased retention of nitrogen
under treated-straw feeding, it is obvious that the better utilization of almost
all the important constituents of the feed such as the proteins, carbohydrates
and minerals must be considered as having an important bearing upon the
practical feeding of farm animals.
Special features of alkali-treated paddy straw.—It has been mentioned
in the introduction that, under the conditions of paddy-straw feeding, the
absorption of calcium is of a low order and the balance for this mineral is
usually negative unless a supplement is given. The data on the absorption
and excretion of calcium presented in Tables XVII and XXVIII definitely
show that between the two cereal straws, wheat and paddy, there is a subtle
difference in the way their calcium content is metabolized in the animal's
system.
Certain evidences are available which point out the factors, present in
paddy straw, responsible for a general deleterious influence upon metabolism.
C