B. C. RAY SARKAR AND K. C. SEN 227
effect was, however, produced upon the plasma
carotene as in the case of butter.
II Effect of heavy dub grass (Cynodon dactylon)
feeding on the carotene and vitamin A potency
of butter
Three cows, Nos. 75, 77 and 78, each in the
sixth month of lactation and yielding 12 lb.,
12 lb., and 15 lb. of milk respectively, were
chosen for this experiment. The investigation
was started in the month of August when the
animals were already getting, in addition to their
concentrate (7.5 lb.) and hay ration, some pasture
by grazing. In order to increase the amount of
carotene ingestion, the hay was eliminated from
the diet, and all the animals were given an excess
of green dub grass, both in the morning and in the
afternoon, for a period of 20 days. The aver-
age daily consumption of the fresh grass was 37.3
lb. A daily estimate of the carotene intake was
made for the last ten days of the experiment, and
faeces was also simultaneously collected for calcu-
lating the carotene balance. Milk samples from
individual animals were also collected for the last
three days and kept separately in the refrigerator.
The first collection was analysed individually and
then composite milk samples were prepared from
the last two days' collection for each animal.
A separate study of the carotene and vitamin A
potency showed that ten days feeding was suffi-
cient to bring the level of carotene and vitamin A
in the milk to an equilibrium [Loy et al., 1937].
The dub grass contained 29.4 mg. of carotene per
lb. of the green material, the dry matter content
being 27 per cent. This high dry matter content
was due to a short spell of dry weather during the
period of investigation. In Tables XI and XII
data are given showing the effect of the dub,
grass feeding on the potency and on the amount
of recovery of carotene in butter fat. It will be
seen that, with an ingestion of a little less than 2
million I.U. of carotene from an average daily
consumption of 37.3 lb. of fresh dub grass, the
total potency was about 10,000 I.U. per pound
of fat, the carotene contributing about 25 per cent
of the total potency. With this amount of in-
gestion, the total recovery was only 0.34 per cent
of the intake. Thus the values of both the total
protency of butter fat and the percentage recovery
on an intake of about 2 million I.U. are more or
less the same in the case of dub grass, berseem and
oat grass feeding.
The carotene balance data of the animals on
heavy dub grass feeding are shown in Table XIII.
It will be seen that, when the average intake was
1098 mg,. all the animals were in positive carotene
balance, the average excretion through faeces
being 56.0 per cent of the intake. The retention
is, therefore, somewhat greater than that in the
case of berseem or oat grass, which were fed at a
higher level.
SUMMARY
1. The chemical composition of milk (fat,
solids-not-fat, total protein, ash) remains constant
when a dry ration is replaced by heavy green fodder
feeding. The R. M., Polenske and iodine values
of the butter fat, however, appear to increase while
the saponification number is not affected.
2. An ingestion of carotene from 1.5 million
to 3.0 million I.U. produces an identical maximum
potency (10,000-11,000 I.U.) per lb. of fat and thus,
an excessive feeding of green fodder does not
lead to any profitable results so far as vitamin A
potency of butter fat is concerned. Feeding of
35 lb. of berseem, dub grass or a little over 45 lb.
of average mixed green fodder or pasture grass
would be sufficient to produce this potency.
On this level of intake, the carotene digestion is
roughly 30 per cent while the carotene recovery
in milk is about 0.09 per cent of the total intake.
The carotene contributes about 24 per cent of the
total vitamin A potency of butter.
REFERENCES
Bal, D. V. and Shrivastava, R. C. (1940). Nagpur
Univ. J. No. 6, 133
Davies, W.L. (1939). The Chemistry of Milk; 2nd edn.
Chapman & Hall Ltd., London, 66
Das Gupta, N. C. (1942). Private communication
Das Gupta, S. M. (1939). Indian J. Vet. Sci. & Anim.
Husb. 9, 249
Dean, H. and Hilditch, T. (1933). Biochem. J. 27, 889
Doctor, N. S., Banerjee, B. N. and Kothavalla, Z. R.
(1940). Indian J. Vet. Sci. & Anim. Husb. 10, 63
Loy, W. C., Hilton, J. H., Wilbur, J. W. and Hauge, S. M.
(1937). J. Dairy Sci. 20, 31
Makhijani, J. K. and Banerjee, B. N. (1938). Indian
J. Vet. Sci. & Anim. Husb. 8, 13
Sen, K. C. and Ray Sarkar, B. C. (1942). Indian J. Vet.
Sci. & Anim. Husb. 12, 179
Seshan, P. A. and Sen, K. C. (1942). J. Agric. Sci. 32,
194