S. K. MUKHERJEE, K. SWAMINATHAN AND B. VISWANATH
233
EXPERIMENTAL
The analyses were carried out during
the
period 10 June, 1938 to 21 September, 1938.
Samples of milk were received from cows of
the pedigree herd of Sahiwal of the Institute.
Particulars of the animals whose secretions
were analysed are given in Table II.
TABLE II
Description, etc. of the animals
No.
776. Heifer
.
.
.
.
.
769. Heifer
.
.
.
.
.
.
771. Heifer
.
.
.
.
.
.
772. Heifer
.
.
.
.
.
.
773. Heifer
.
.
.
.
.
.
763. Heifer
.
.
.
.
.
.
736. Cow 2nd Calver
.
.
.
.
.
740. Cow 2nd Calver
.
.
.
.
.
742. Cow 2nd Calver
.
.
.
.
.
716. Cow 3rd Calver
.
.
.
.
.
710. Cow 3rd Calver
.
.
.
.
.
674. Cow 3rd Calver
.
.
.
.
.
706. Cow 3rd Calver
.
.
.
.
.
644. Cow 4th Calver
.
.
.
.
.
653. Cow 4th Calver
.
.
.
.
.
604. Cow 5th Calver
.
.
.
.
.
569. Cow 8th Calver
.
.
.
.
.
Date of
birth
10-6-36
18-3-36
6-4-36
29-4-36
3-5-36
29-12-35
1-12-34
27-12-34
5-1-35
14-3-34
12-2-34
10-12-32
23-12-33
10-9-31
. .
. .
. .
Date of
service
25-12-37
29-6-38
18-11-37
3-12-37
25-11-36
11-9-37
25-11-37
. .
7-11-37
25-11-37
22-11-37
24-11-37
26-9-37
. .
23-11-37
5-12-37
25-11-37
Period of gestation
Months
6
. .
9
9
9
9
9
. .
9
9
9
9
9
. .
9
9
9
Days
15
15
6
3
9
2
14
. .
7
4
9
12
6
. .
6
4
15
Calved after service
Months
. .
. .
9
9
9
9
9
. .
9
9
9
9
9
. .
9
9
9
Days
. .
. .
9
8
10
17
16
. .
16 6
12
15
9
. .
7
4
15
The samples of secretions were obtained in
clean bottles and were kept in iced water at a
temperature of about 10º C. They were imme-
diately taken to the laboratory for analysis and
were shaken properly before each pipetting.
Total solids, ash, casein, lactose and acidity
were estimated according to the A. O. A. C.
methods of analysis [1935]. Fat was estimated
by Gerber's H 2 SO 4 —amylalcohol method and
Sp. gravity by means of the Westphal balance
(7). Total protein was separated by 4 per
cent. trichloracetic acid from the non-proteins
(3).
Albumin was at first determined directly
by the A. O. A. C. method [1935], but it was
subsequently found not suitable in presence of
globulin.
Later on, globulin was directly esti-
mated by the satd. MgSO4 method [1937], and
the albumin content was obtained by difference.
Colostrum milk and premilk coagulated on
heating.
The coagulation was studied as fol-
lows—colostrum or premilk was diluted with
the requisite amounts of normal milk in test
tubes to make dilutions of 10 per cent., 15 per
cent, 20 per cent, and so on with respect to
normal milk.
The test tubes were then stop-
pered and kept in a boiling water bath. After an
hour or so, flocculation, if any, was observed.
The minimum dilution for complete coagula-
tion, was put down as the coagulating power
of the secretion. Thus 10 per cent coagulation
means that 1 cc. of colostrum is the minimum
quantity coagulating 9 cc. of normal milk.
Since normal milk does not coagulate by itself
the coagulating test was a criterion for judging
the stage of transition from colostrum to normal
milk.
The results of analysis are summarized in
Tables III to VI. Instead of showing the day
to day variations of the various constituents,
only the compositions of the secretions on the
first day of withdrawal, just before calving and
just after it, and at the normal milk stage are
recorded.
These clearly indicate the transi-
tional phases in the production of milk.
The change from premilk to normal milk is
characterized by two transitional stages. Firstly,
premilk to colostrum and secondly from colo-
strum to normal milk.
The compositions of
the secretions with reference to these
two
stages are discussed below.
Premilk and colostrum have higher percent-
ages of total solids than normal milk. In pre-
milk the high total solids are associated with
a high protein content, whereas in colostrum it
is due to the high fat content.