PHOSPHORUS IN MILK

II. AVAILABILITY OF PHOSPHORUS OF THE MILK OF COW, GOAT AND BUFFALO

By K. P. BASU and K. P. MUKHERJEE, Biochemical Laboratory, Dacca University

(Received for publication on 19 January 1943)

THE importance of the minerals, calcium and
phosphorus in growth and metabolism is too
well known to merit a further discussion. Sherman
and his collaborators [1922, 1935] as also Rose and
MacLeod [1923] and Fairbanks and Mitchell
[1938] have shown that calcium from different
sources, specially that from vegetables is not as
well utilized as that from cow's milk. The differ-
ence in the utilization of calcium from differ-
ent food materials raises the question whether the
phosphorus of all food-stuffs are equally available.
Much work has been done on the availability
of phytin phosphorus [Bruce and Callow, 1934;
McCance and Widdowson, 1935; Lowe and
Steenbock, 1937; Palmer and Mottram, 1939;
Harrison and Mellanby, 1939; Kreiger and
Steenbock, 1940] and most of these investigations
show that phytin phosphorus is very poorly
utilized by human beings and animals.

Williams, MacLeod and Morrel [1940] have
compared the availability to the animals of the
phosphorus of a low and of a high phosphorus
hay and have found that the phosphorus of the
low phosphorus lespedeza sericae or alfalfa hay is
less available to the rat for growth and bone
development than the phosphorus of a high phos-
phorus hay of the same type.

The importance of milk and milk products in
the nutrition of the infant and the growing animals
as well as in the dietary of large masses of adult
population requires that special attention should
be given to this secretion as a source of phosphorus.
The present investigation was carried out to
determine the availability of phosphorus in three
commonly used varieties of milk, viz. that from
goat, buffalo and cow. Of these the buffalo milk
has a higher phosphorus content (125 mg. per
100 c.c. of milk). The cow milk contains 97
mg. per 100 c.c. and the goat milk 100 mg. per
100 c.c. The total solid contents of the buffalo
milk is also much higher than those of the cow and
the goat milk and hence the phosphorus content
of dried buffalo milk is lower than in dried cow
and goat milk.

Very little work has appeared on the availability
of phosphorus of milk from buffalo, goat or cow.
Henry and Kon as well as Auchinachie [1937]
observed a retention of about 80 per cent of the
phosphorus and calcium in cow's milk ingested by
experimental rats.

The availability of the phosphorus of these
milks was investigated by experiments with young
rats. Young healthy albino rats which had been
reared on the usual diet of the laboratory were
placed on three different diets in which goat milk,
cow milk and buffalo-milk were respectively the
only source of phosphorus. At seven weeks of age
the rats were killed and the utilization of
phosphours was determined and compared. This
method would throw light on the relative value
of the different milks in promoting growth and
retention of phosphorus in young growing rats and
probably, therefore, in growing children.

During the experimental periods the rats were
so kept within the room so that all the rats were
exposed to the same conditions of light.

                  EXPERIMENTAL

The different varieties of milks were obtained
from the Government farm at Dacca. Six seers
of different varieties of milk were evaporated
to dryness on the water-bath. The whole dried
milks were separately finely ground, the whole
lots were thoroughly mixed and finally stored in
stopperd glass jars in a refrigerator. The same lots
of milk were used throughout the investigation.

The powdered milks used in preparing diets
were analyzed. In all cases Ca was determined
by the McCrudden method [1911-12] by precipi-
tating Ca. as oxalate at pH. 4.8—5.2 using
methyl red as indicator and titrating the oxalic
acid with potassium permanganate solution.
Phosphorus was determined colorimetrically by the
method of Youngburg and Youngburg [1930]
after ashing the materials under investigation
at 500º—600º in an electric muffle. Nitrogen
was estimated by the usual Kjeldahl method.
Moisture content was determined by heating the
powders in aluminium vessels in a steam-oven for
three days.

The results are shown in Table I.

                                          TABLE I
                        Analysis of whole dried milks

Healthy young rats (albino) four weeks of age
which had been reared on the stock laboratory
diet consisting of whole weight, cow's milk and
green vegetables with bi-weekly addition of codliver
oil and marmite were placed in individual iron
cages with raised bottom and maintained on the

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