K. C. SEN AND P. A.
SESHAN
175
assay of the vitamin-A contents of the normal liver of some animals such
as oxen, guinea-pigs, rabbits rats and dogs showed considerable variations,
the liver of the guinea-pig being the least and that of the oxen the most potent
[Simmonet et al, 1932]. Goat liver was found to have a reserve more than
twice that of the bull liver and six times that of rabbit liver [Sen and Sharma,
1936]. The livers of cows had about four to five times the vitamin-A contents
of those of bullocks, while calves showed no such difference between the
sexes [Ender, 1934]. Eighteen-month-old rats which had finished breed
ing were fed for about twelve weeks on a vitamin-A sufficient diet super
imposed by a large amount of some concentrate. The vitamin-A concentra
tion in the liver at the end of this period was 18,000 blue units per grm. Put
on to a deficient diet at this stage, the concentration fell down to 2,700 units
per grm. in four weeks and in twelve weeks to about 400 units [Davies and
Moore, 1935]. Some beef steers receiving throughout the summer a diet
found optimal for storage purposes were changed to a diet deficient in vita
min-A. Sixty-three, 121 and 282 days later it was estimated that there
was a progressive decrease in the vitamin-A of the livers showing that there
was a continuous depletion from the amounts stored when they had been
fed in excess. The concentration of vitamin-A in the livers of cows receiv
ing a rich ration was found to be approximating to that in cod-liver oil. New
born calves from well-fed cows showed only a low concentration of vitamin-A
in their livers, although the colostrum was rich [Guilbert and Hart, 1934].
Rats which had received vitamin-A to the order of 5,000 times the necessary
minimum before and during gestation threw young ones with only small
amounts in their livers. These amounts could be slightly increased by feed
ing a diet to the mother which was rich in fat as well as in vitamin-A [Dann,
1934].
Although it has been shown that a high vitamin-A reserve in the liver
of a cow did not give rise to a high vitamin-A content in the liver of her calf,
it has been shown by several workers that it is immediately reflected in her
milk and butter. The fact that the carotene and vitamin content of the feed
exert a considerable and proportionate influence upon the carotene and vita
min-A of the milk and butter-fat has been borne out by a large volume of work
wherein studies have been made with various concentrates and vegetable
and plant feed as sources of the vitamin-A intake [Moore, 1932 ; Fraps and
Treichler, 1932 ; Copeland and Fraps, 1932 ; Watson et al, 1933 ; Gillam
et al, 1933 ; Baumann et al, 1934 ; Fraps et al, 1934 ; Converse et al, 1935 ;
Beeson, 1935 ; Hilton et al, 1935 ; Wilbur et al, 1935 ; Treichler, 1935 ;
Steensberg, 1936].
During the course of the work on the effect of the feed on the carotene
and vitamin-A content of milk and butter, it was observed that the breed
of the animal was also a factor in transmitting the reserves in the system
through the milk. In cows kept under comparable conditions, Guernsey
cows' butter gave a carotene value of 7.8 γ per grm. while Holstein and
Ayrshire gave 4.3 γ per grm The vitamin-A. content on the other hand
was only 5.1 γ in Guernsey while it was 10.1 γ in the case of the Holstein.