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both in the form of carotene and as colourless vitamin-A [Hart and Guil¬
bert, 1933]. In an experiment on cows it was observed that there were small
amounts of carotene and much larger amounts of vitamin-A in the liver
and milk fats. By feeding carrots, a rich source of carotene, at the end of
winter feeding, both the vitamin-A and the carotene contents of butter in-
creased [Moore, 1932]. It becomes clear, therefore, that so far as animals
are concerned, the problem of vitamin-A deficiency resolves itself into an
adequate provision of carotene in their normal feed which consists of grains,
milled products and forage crops.
Many observations have been recorded to the effect that carotene is
closely associated with the pigments in a material. Yellow maize was found
to be richer in vitamin-A than white maize [Mangelsdorf and Fraps, 1931].
Yellow corn and yellow corn meal seemed to be rich sources of vitamin-A
while white corn contained little, if any. It was also noticed that the soil
and season had influences on the vitamin-A content [Fraps, 1931]. Flour
from wheat grown on irrigated land had a lower carotene content than the
flour from dry land wheat [Whiteside, 1931]. In five varieties of maize it
was found that the yellow variety had a higher vitamin-A potency than the
white ones. The correlation between vitamin-A content and colour was true
only with respect to the endosperm, the depth of colour of the pericarp being
immaterial [Takahashi and Masuda, 1935]. In studying the distribution
of carotene in the wheat grain, it was also observed that the variety of wheat
had a greater influence than location, season or storage. The flour prepared
in each case had a lower carotene content than the whole wheat. Bran had
the highest concentration of carotene, then middlings, second patent flour
and first clear flour, while the first patent flour had the least [Fifield, 1936].
The carotene content of twenty-nine varieties of whole wheat and seventy-
two hybrid strains showed variations in two years of 1.66—3.80 parts per
million and 1.80—3.80 parts per million. This work also showed that the
carotinoid pigmentation of wheat was an inheritable characteristic, some
of the strains being homozygous and some heterozygous for this characteristic.
The breeding of wheat of a given carotene content would thus appear to be
possible [Worzella and Cutler, 1935].
Notwithstanding these studies on the carotene content of some cereals,
grain feeding as such has not been considered as a source contributing to the
vitamin-A needs of animals. White corn and oats as the main feed of kids
resulted in serious avitaminosis-A [Longwell and Weakley, 1932]. To a
vitamin-A free diet of young rats a supplement of two grm. daily of English
wheat, oats or barley was added from the twentieth day. The animals grew
well for about three weeks and then lost weight and died. The initial stimulus
to growth was attributed to the xanthophyll in the cereals and not to any
carotene therein [Malimberg and Euler, 1936]. A basal ration containing
white corn, fish meal and mineral mixture caused a cessation of growth in
pigs and later induced a severe type of avitaminosis-A [Hostetler et al, 1935].
The vitamin-A potency due to the carotene in the butter of a cow fed on