A STUDY OF THE VITAMIN A AND CAROTENE CONTENT OF
COW'S MILK DURING ONE COMPLETE LACTATION
By DALIP SINGH, M.Sc. (PB.), Ph. D. (CANTAB.), Agricultural Chemist
to Government Punjab, Lyallpur and FATEH MOHAMMAD, B.Sc. (Agri.).
Chemical Assistant, Punjab Agricultural College, Lyallpur
(Received for publication on 24 August 1944)
THE importance of vitamin A as an
essential ingredient of human diet cannot
be over-emphasized. A regular supply of it
the system is indispensable for the
proper development and functioning of the
body and as a preventive measure against
usceptibility to disease. A number of
orkers have made quantitative studies on
the daily requirements of Vitamin A (or
s precursor carotene) for various types
of animals, for keeping them in good
health. Thus, Ward, Bechdel and Guer-
ant [1938] found that 12-18 microgrammes
of carotene are required per lb. of body
weight per day for growing dairy calves
to prevent A avitaminosis. Converse and
Meigs [1938] have deduced the carotene
equirements of cows for normal reproduc-
tion and calving to be 80-100 mg. daily
during the last months of gestation; the
amount below 60 mg. per cow per day
resulting in a considerable proportion of
till-born calves. Kuhlman and Gallup
[1941] working with lactating cows of
ersey breed arrived at the conclusion that
0-45 microgrammes of carotene per lb. of
body weight (or 40-45 mg. for a 1,000 lb.
animal) is about the minimum daily re-
uirement for normal lactation. With
amounts lower than 40 microgrammes, the
lactation was likely to be impaired; the
calves born were weak and the cows
developed abnormal conditions. Similarly,
it has been ascertained that about 4 mg.
is the minimum daily dose for man.
The most important source of supply
of vitamin A for cattle is green roughage.
Seshan and Sen [1942] have determined
the carotene content of a large number
of green roughages ordinarily fed in this
country, and the amount of fodder neces-
sary to meet the vitamin requirements of
main types of animals can easily be calcu-
lated. The problem of feeding cows,
however, is somewhat different. As a
milch animal, the cow requires vitamin A
not only for her own system but also for
secretion in milk which forms one of the
important sources of vitamin A for the
consumer. Studies on the relationship
between the carotene content of the feed
and that in the milk have been carried out
by many workers. Moore [1932] has
shown that in the cow carotene of the feed
undergoes conversion to vitamin A and is
secreted in the milk partly as carotene as
such and partly as vitamin A. Kennedy
and Dutcher [1922] demonstrated as early
as 1922, that the vitamin-A value of milk
is influenced by the vitamin-A value of the
feed.
Kraus [1931], Watson [1932] and
others have shown that pasture grass is
rich in vitamin-A factor and produces a
milk of high vitamin-A activity. Recently
a more quantitative study has been made
of this problem. Hogdson and co-workers
[1938] have found that the average
percentage of the carotene ingested which
was secreted as carotene in the butter fat
was 0.71 for cows receiving hay, 0.22 for
cows receiving hay and silage, and 0.12 for
cows receiving silage only. Similarly,
Bartlett and co-workers [1938] and Seshan
and Sen [1942] arrive at the same con-
clusion, viz. increased intake of carotene is
followed by the increased carotene and
vitamin-A potency of milk.
The studies of Henry, Housten and
Kon [1940] on the vitamin content of the
first milk or colostrum have brought out
its amazing richness in vitamin A and
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