S. V. DESAI AND M. L.
MATHUR
199
alfalfa hay and salts, larger amounts were eliminated
than were ingested. Meigs, Blatherwick, and Cary
[1919] found that dry pregnant cows were not assi-
milating calcium from calcium-rich rations, but
were actually transferring calcium, salts from their
skeleton for building the foetal skeleton. Hart,
Steenbock and Hoppert [1921] observed that in
dry and milking goats calcium assimilation was
greater when green instead of dry oats were fed.
Cod liver oil (5-10 c.c. per day) consistently changed
a negative to a positive balance. Hart el al. [1922]
found that high-yielding cows were maintained in
positive calcium and phosphorus balance on dry
alfalfa hay, corn silage and grain mixture. Their
subsequent findings [1922], in which timothy hay
was used, are not in harmony with the observations
quoted above. Bone-meal supplement did not
bring about positive balance. Forbes et al. [1922]
found that the calcium of the bones was more readily
available for purposes of milk elaboration than the
calcium of the rations and the mineral supplement.
They came to the conclusion that calcium meta-
bolism was characterized by its rapid loss from the
body during early period of lactation and its reten-
tion during the dry period with most rapid storage
at the end of the period of gestation. At the time
of high milk production, if the food was sufficient
to maintain the life of the cow, she would produce
milk, even though this involved an extensive drain
upon the tissues of her body. Hart et al. [1922-23]
took up the work again and found phosphorus equi-
librium was maintained without, and calcium
equilibrium with, bone-meal and green grass supple-
ment.
The cows of the Sahiwal herd at our dairy farm
were reported to be licking earth while grazing. As
the cows were fed with protein-rich concentrates,
green fodder and mineral mixture as 'Churn Flour'
this habit of theirs could not be explained. The
earth was analysed, but nothing particular was
discovered, which could account for this peculiar
habit and it was suspected that probably more
calcium and phosphorus were excreted by our cows
than they were ingesting from the feeds. The
present investigation was undertaken to ascertain
if there was variation in the percentage ratio and
total output of calcium and phosphorus in relation
to the yield of milk, age and stage of lactation in the
case of the Sahiwal breed of cows and if so to what
extent. The above factors in relation to dry and
green fodder were also examined.
EXPERIMENTAL
Preliminary experiments were carried out to study
the suitability of methods of analysis and to ascer-
tain (i) whether there was any variation in the per-
centage of calcium and phosphorus in the different
milkings of the day and whether these differed
from that found in a composite sample of the day's
milk, (ii) whether the total amount of calcium and
phosphorus in all four milkings differed from that
calculated from the composite sample, (iii) whether
the ratio CaO : P 2 O 5 was constant, and (iv) whether
there was any change in the percentage of calcium
and phosphorus in the day-to-day milk.
For this purpose, three high and three low milk-
ing cows, first calver, second calver and adult, all
in the same stages of lactation (8th week), were
selected. Samples of milk were taken from all
the four milkings and composite samples of the milk
was prepared by taking 5 c.c. per lb.
The milk was ashed by Neumann's method [1902-
03] which was found quite satisfactory. Ten c.c.
milk was taken out with a pipette in a 100 c.c.
Kjeldahl flask. A separate aliquot of 10 c.c. was
weighed in a tared weighing bottle. For calcula-
tion, the average weight of 10 c.c. of milk was used,
as the difference in day-to-day weight was not very
much. But before calving 10 c.c. of milk was
weighed separately each day. The milk was ashed
with 5 c.c. concentrated sulphuric acid and nitric
acid and the solution made up to 100 c.c.
Twenty-five c.c. aliquot was taken and calcium esti-
mated by Kraut's method [1856]. Ten c.c. aliquot
was taken and phosphorus estimated by Pemberton's
method [1882].
These preliminary experiments revealed that (1)
the percentage of these elements in samples of the
different milkings of the day did not vary much
among themselves or from the composite sample
of the day, (2) the percentage of these elements in
day-to-day samples of the milk did not differ much
and (3) the ratio of CaO : P 2 O 3 also did not show
much variation.
For comprehensive studies, 12 high-milking
and 12 low-milking cows of different ages and
in the various stages of lactation were selected.
The lactation of some of these cows commenced
before they calved. Samples of milk were taken
once a day at 9 a.m. milking and analysed. The
concentrates as well as green and fresh fodders were
also analysed for calcium and phosphorus, the latter
at an interval of ten days.
One pound of mustard cake per cow was also
given from 1 to 10 August and half a pound
of boiled linseed per cow was given to those which
were in the first 100 days of lactation.
In addition to these concentrates, the cows were
taking 20 lb. of green fodder (cowpeas and jowar
mixture), three pounds of berseem hay and three
pounds of bhusa. While grazing, they could take
about 20 pounds of grass.
The grains, oil cakes, berseem hay and bhusa were
analysed for calcium and phosphorus. The results
are given in Table IV.
D 2