258
Studies on Protein Metabolism, I
(iii) Supplements. The following supplements
were added to the concentrate :—
(a) Salt mixture—
Calcium carbonate
.
.
.
.
Sodium phosphate (Na 2 H PO 4 .12H 2 O) .
Pot. hyd. phosphate
.
.
.
.
Magnesium carbonate .
.
.
.
Sodium citrate
.
.
.
.
.
(b) Oil mixture—
Cod liver oil
.
.
.
.
Olive oil . . . . .
Groundnut oil
.
.
.
.
.
25 parts
35 „
20 „
19 „
1 „
20 parts
20 „
60 „
(iv) Scale of rations. The following low-nitro-
gen and nitrogen-free rations (expressed on dry
basis) were fed per 1,000 lb. body weight.
(a) Low-N ration No. 1—
Sago .
.
.
.
.
.
.
Sugar (crystalline, extra white)
Wheat bhusa
.
.
.
.
.
Oil mixture
.
.
.
.
.
Salt mixture
.
.
.
.
.
Common salt
1,750 gm.
270 „
4,540 „
80 „
170 „
ad lib
(b) Low-N ration No. 2—
Similar to ration No. 1 except that the cold
alkali-treated wheat bhusa replaced the untreated
bhusa.
(c) N-free ration
Sago
Sugar (crystalline, extra white)
Bagasse (hot alkali-treated) .
Oil mixture .
.
.
.
.
.
Salt mixture
.
Common salt
.
2,500 gm.
270 „
1,670 „
80 „
170 „
ad lib.
The nitrogen-free ration was considered to be
adequate in every respect except protein which
had been reduced to as low as 0.014 lb. of crude
protein as compared with 0.6 to 0.8 lb. of diges-
tible protein advocated by Kellner [1926] for an
animal weighing 1,000 lb. It provides about 6 lb.
of S. E. which is considered to be sufficient for an
animal of 1,000 lb. body weight. The vitamin B
complex and vitamin C offered no serious problem in
cattle feeding as McElroy and Goss [1939; 1940, 1,
2, 3], Wegner et al. [1940] and Crampton [1941]
have pointed out that thiamine, riboflavine, panto-
thenic acid and pyridoxine are synthesized in the
rumen, and it is believed that vitamin C is
also synthesized in the body. The amount of dry
matter ingested per day varied from 10 to 15 lb.
per 1,000 lb. body weight.
Experimental animals and technique
In this investigation adult bullocks, six to eight
years of age, were used. In the first experiment
the subjects consisted of three local hybrid bullocks
weighing 500—600 lb., while in the second one
Hariana animals weighing 800—1,200 lb. were
employed.
In the first experiment the animals were fed
low-N ration No. 1 for 14 days, followed by low-N
ration No. 2 for 10 days. Finally, the N-free
ration was fed for five days. The pre-experiment-
al feed consisted of a maintenance ration contain-
ing wheat bhusa and mustard cake. From the
concluding stages of the low-N period, the appetite
of the animals declined and the food consumption
decreased. In order to feed the required amount
of ration, therefore, the part of it left over was fed
by hand. The animals did not usually refuse this
method of feeding and gradually became used to
it.
Previous to the experimental period, the bullocks
in the second experiment were kept on a mainte-
nance ration consisting of wheat bhusa and
mustard cake for one month. They were then
fed low-N ration No. 1 for 15 days. For the
next 20 days, they were fed a mixture of low-N
rations Nos. 1 and 2 in equal proportions. This
was followed by the N-free ration for nine days.
The animals were housed in metabolism stalls
provided with suitable arrangements for the
quantitative collection of urine free from conta-
mination. Immediately on voiding, the urine
drained into glass bottles containing a little toluene.
The collections were removed to a refrigerator
within half an hour after urination, and the 24
hours' samples were measured and analysed.
Representative samples of urine collected for
24 hours were analysed for total nitrogen every
day. Nitrogen partition of urine was also deter-
mined on most of the days. Total sulphur and
sulphates were estimated during certain periods in
the composite samples made up of aliquots taken
daily. The ration mixtures were analysed for
total nitrogen. The methods of analysis were:
total nitrogen, Kjeldahl [1883]; urea and ammonia,
Van Slyke and Cullen [1916]; creatine and
creatinine, Folin [1914]; total sulphur, A. O. A. C.
[1935] magnesium nitrate method with slight mo-
dification; total sulphate, Krishnan (unpublished
work).
In order to see whether any abnormality was
manifested in the urine during the experimental
period, the urine was tested qualitatively every
day for sugar, albumin, acetone bodies, sediments
and pH.
RESULTS AND DISCUSSION
First experiment
The average daily values of duplicate observa-
tions of nitrogen excretion of the last 12 days in the
low-nitrogen period and the entire nitrogen-free
period are given in Table I.