238
Composition of Pre-milk and Colostrum of Dairy Cows
Ash content varies slightly for the different
cows. It is only somewhat higher in colostrum
and premilk than in ordinary milk.
The specific gravity of premilk and colostrum
is generally somewhat higher than that of nor-
mal milk. These high values are parallel with
the high viscosity of the secretions.
Variations of the different constituents from
animal to animal are better correlated with the
period of "drying" than with the age of the
animals or other characteristics.
The range
of variations of some important
constituents
is given in Table VIII from which it would
appear that the range is not much different for
the different animals but the absolute values are
dependent upon the length of time the animals
have been kept "dry".
The length of the
drying period has been calculated from Table
II as the difference between the figures given
in columns 5 and 6.
TABLE VIII
Total solids
Fat . .
Total Protein
Globulin .
Heifers
.
.
.
.
.
.
Cow, 2nd calvers . . . .
Cow, 3rd calvers
.
.
.
.
Heifers
.
.
.
.
.
.
Cow, 2nd calvers
.
.
.
.
Cow, 3rd calvers
.
.
.
.
Heifers
.
.
.
.
.
.
Cow, 2nd calvers
.
.
.
.
Cow, 3rd calvers
.
.
.
.
Heifers
.
.
.
.
.
.
Cow, 2nd calvers
.
.
.
.
Cow, 3rd calvers . . . .
Premilk
(Range)
13.5—24.3
15.8—18.7
13.7—17.4
0.9—3.2
0.3—5.4
0.5—3.2
3.7—16.0
4.0—13.1
7.7—10.2
0.0—6.7
0.68—6.6
1.7—5.1
Colostrum
(Range)
18.4—34.8
16.4—25.7
18.9—26.0
5.6—9.5
5.8—13.0
7.2—11.7
3.5—8.9
3.9—9.6
4.3—11.1
0.83—2.7
0.03—0.86
0.99—3.4
Normal milk
(Range)
13.1—18.5
15.2—17.8
13.3—17.2
5.2—7.3
5.0—8.1
3.3—7.1
3.5—4.0
3.8—3.9
3.5—4.6
0.04—0.39
0.14—0.35
0.27—0.52
Length
of
drying
period
(Range)
in days
1—15
2—9
2—3
From the results of analysis (Tables III, IV,
V and VI) summarized above, it would appear
that in general the secretion withdrawn before
parturition, i.e., the premilk, is characterized
by (1) a viscous consistency, (2) high total
solids, (3) high protein content, especially glo-
bulin, (4) high acidity, (5) low lactose content
and (6) low fat content.
If the premilking
period is long the percentages of the consti-
tuents tend to equalize with those of normal
milk, excepting that the fat content shows an
abrupt rise on the day of calving or the follow-
ing day, there being hardly any increase in the
globulin or the albumin content. If, however,
the period of premilking is short (e.g., two or
three days only) the transition from premilk to
colostrum is more abrupt. The withdrawal of
premilk has thus a normalizing effect on the
composition of colostrum (cf. also results in
Table V).
SUMMARY AND CONCLUSIONS
The secretions from the udders of a number
of heifers and cows of different calvings and
ages, withdrawn before calving, after calving,
and up to the normal milk stage, were analysed.
Total solids, fat, proteins, especially globulin,
showed characteristic variations which could be
correlated with the transitional phases from pre-
milk to colostrum and from colostrum to normal
milk.
Two heifers yielded large quantities of secre-
tions which were almost identical with normal
milk in both physical appearance and chemical
composition.
When premilking is done for a
long time the composition of the secretions
tends to become similar to that of normal milk.
We take the opportunity to express our
thanks to Mr Wynne Sayer, the Imperial Agri-
culturist and to Mr Fernandez, the Cattle
Superintendent for the supply of samples of
milk for the investigation.
REFERENCES
A. O. A. C. Methods of Analysis,
4th Edition 1933
Ashdell, S. A. (1925) J. agric. Sci. 15
Bergmann, A. J. and Turner, C. W. (1937) J. Dairy
Sci. 20
Richmond H. D. (1914) Handbook of Dairy Chemistry
2nd Edn. Charles Griffin & Co. Ltd. London
Sivassubramanian, S. and Dover, C. W. (1938) Indian
J. vet. Sci. 8, 28
Shah, A. A. (1936) Indian J. vet. Sci. 6, 234
Woodman, H. E. & Hammond, J. (1923) J. agric
Sci. 13, 180