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Vitamin-A Deficiency in the Diet of Farm Animals
white maize decreased from thirty per cent at the beginning of the experiment
to one per cent near the end. With yellow maize instead, the decrease was
from forty-seven to nine per cent only [Treichler et al, 1935].
With regard to the soya bean too, the available data are conflicting. In
fresh soya bean grown near Leipzig, vitamin-A was found in traces [Scheunert
and Schieblich, 1935] while other experiments showed that the soya bean was
so rich in vitamin-A that it could serve as the sole source of vitamin-A for
feeding growing rats [Iwanova, 1935]. The carotene content of soya beans
in India has been estimated as 710 international units per 100 grm. [Aykroyd,
1936]. On the other hand, when the linseed oil meal in the grain feed of a
dairy ration was replaced by raw or cooked soya beans, the vitamin-A value
of butter went down from the neighbourhood of 23 to 28 Sherman units to
about 15 to 18 units per grm. The replacement of alfalfa hay by soya bean
hay had also a similar effect [Wilbur et al, 1935].
It should be mentioned here that vegetable oils such as earthnut, gingelly,
cocoanut, linseed, mustard and hemp seed oils were found to contain very
negligible traces of vitamin-A, red palm oil being the only exception [Rose-
dale and Oliviero, 1934 ; Lo T-Y, 1935]. A spectrographic study of several
vegetable oils in this country also showed that they were all negative for
vitamin-A [De, 1935]. Vitamin-A being a fat soluble one, the oil cakes
that are generally used in animal feeding would not contain any significant
amount of this constituent. It is apparent, therefore, that to provide an
adequate supply of vitamin-A in the feed of animals in general and farm
stock in particular, a proper choice of forage plants either as the main feed or
as a supplement is the only possible method.
It would be useful in this connection to remember that there are certain
factors which affect the vitamin-A content of vegetables and plants in general.
White, yellow, orange, garden and field varieties of carrots, grown under
greenhouse conditions, showed on analysis that the most highly coloured
carrots contained 9.6 mg. of carotene per 100 grm. while white varieties yielded
only l/80th of this amount [Bills and McDonald, 1932]. The vitamin-A
content of the outer green leaves of Iceberg lettuce was found to be 34.5
Sherman units per grm. of leaf, while the inner bleached leaves gave a con-
tent of 1 unit [Munsell and Kennedy, 1935]. A study of the variations in
the carotene content of Kentucky blue grass, green growing alfalfa, carrot,
etc., revealed the fact that green plants were very rich and dried or brown
leaves very poor in carotene [Shinu et al, 1935]. The carotene content of
the corn plant and of the silage made from it was found to depend upon the
greenness of the plant at cutting [Kane and Cary, 1935]. Veld grass samples
from Bechuanaland showed a low carotene content at different seasons during
two years. Only the fresh growth after rain was rich and there was pro-
gressive deterioration as the pasture dried up [Myburgh, 1936].
It has further been observed that manuring had no effect on the carotene
or the vitamin-A activity of Cumbu leaves and that under all conditions
of growing the carotene content decreased with the age of the crop (Sci. Rep.