J. K. MAKHIJANI AND B. N. BANERJEE                     27

grass consumed was obtained by subtracting the residue from the quantity
provided. The milk-yield was measured each day and the fat percentage
was calculated on weekly averages. A weekly average sample of butter was
used for carotene and vitamin A estimation. The blood was drawn once a
week for carotene estimation.

                    DISCUSSION AND SUMMARY

Karrer and Schlientz [1934] have shown that carotene from grasses, spinach
and nettles may be regarded as pure β carotene. Smith and Milner [1934]
found leaf (alfalfa) carotene to consist mostly of β carotene. Again β
carotene produces vitamin A in the physiological system in equivalent
amount and α or γ carotene produces vitamin A in only half the amount.
Apparently, therefore, the variation in the form of carotene occurring in
common forage plants is a negligible factor in expressing vitamin A value
from the carotene content.

In the process of drying for analysis with hot air at 45°C. for 24 hours
the carotene loss was very little. Some of the samples that were sent in the
green stage sometimes became a little mouldy and suffered a little loss on this
account. Duplicate trials have proved that the method followed yielded
reliable and concordant results.

In a feeding trial for a short period, it is not possible to deduce any defi-
nite conclusions. In a trial on lactating cows it is not possible to measure
the vitamin A reserve before or after the experiment. The stored up vitamin
A is so slowly used up when carotene supply is in deficit, that no detectable
difference can be noted in milk [Schieblisch, 1932]. However, the yellow
value in butter and the carotene content of blood go to show that increased
carotinoid feeding helps to build up reserve of vitamin A in the animal and
a slight increase in the milk supply. Further intensive work is necessary
to solve the many complicated phases of the problem. It would, of course,
be desirable to know which breed of cattle in India produces milk richest in
vitamin content.

We wish to take this opportunity to thank the Directors of Agriculture
of various provinces in India and other gentlemen, too numerous to be in-
dividually mentioned here, who very kindly supplied us samples of grasses,
fodders and concentrates. Thanks are also due to Mr. Zal R. Kothavalla,
the imperial Dairy Expert, for this valuable suggestions and criticisms and
to Dr. V. Subrahmanyan, Professor of Biochemistry, Indian Institute of
Science, Bangalore, but for whose co-operation, this work could not have
been undertaken. Dr. G. S. Siddappa very kindly performed a number of
determinations and thus helped us in checking and duplicating many of the
carotene values in this paper to test the accuracy of the methods employed.