90
Vitamin-A Requirement of Farm Mammals
degeneration with engorgement of the
liver, the excess of carotene producing an
intense yellow or reddish colour. The
cause of the condition was not determined.
Carotene has been supposed to have
some relation to one of the commonly occur-
ring off-flavour termed 'oxidized'. It was
found by Guthrie, Roadhouse and Richard-
son [1931] to result from contact of the
milk with Cu or Cu alloys. Kende[1932]
studied the relation of the diet given to
cows to its development. It occurred in
winter, and green feed or fresh hay was
shown to contain considerable amounts
of reducing substances which tend to pre-
vent oxidized flavour or lessen its intensity.
Anderson [1936] and Anderson, Wilson
and Hardenbergh [1937] have concluded
that the substance responsible for the
beneficial effect of green food, artificially
dehydrated alfalfa and carrots in preven-
ting 'oxidized' flavour was carotene.
Whitnah, Martin and Beck [1937] showed
that spontaneously occurring oxidized
flavour could be prevented on high caro-
tene rations. Beck, Whitnah and Martin
[1939] found no relation between frequen-
cy of occurrence of oxidized flavour and
the lecithin or vitamin A content of the
milk but it was effectively prevented by
giving as little as 206 mg. carotene per
head daily to cows that had been constant-
ly producing milk with this off-flavonr.
Brown, Vanlandingham and Weakley
[1939] found that ascorbic acid given at
the rate of 1 g daily partly, and carotene
given at the rate of 350 mg. daily greatly
reduced the production of 'oxidized flavour'
by contact with metals. They were of the
opinion, however, that the spontaneous
development of oxidized flavour was not
due to the ration being low in carotene.
The literature contains many references
on the vitamin A and disease but that
subject is too large to be covered in this
review although some references to it have
been made.
Epithelial cells are widely distributed
in the body. It is logical to consider that
the keratinisation of these cells would
lower their resistance to invasion by
bacteria and parasites. Many of
lesions produced in vitamin A deficiency
result from secondary bacterial invasi
and, in advanced cases of such deficien
these lesions overshadow the primary defi
ciency and are the apparent cause of death
The claims of enthusiasts for the pr
phylactic action of vitamin A against infec
tions have not been substantiated by ex
perimental and clinical data. Neverth
less it is a safe maxim that to support
adequately the requirements of vitamin
in the rations of our animal populations
a part of good husbandry. It takesi
place with many other factors in mai
tenance of better health, well being an
production.
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