136
Deterioration of Cattle in Certain Parts of India
deficiency or imbalance and has cleared up
the existing confusion in their classification by
using the terms in their precise histopathological
sense. He has also suggested that the endocrine
mechanism may be of significance in controlling
the mineral metabolism, a point which needs fur-
ther research.
Humphrey [1931] has remarked that vitamins
are substances of very pronounced physiological
activity, and can produce remarkable changes in
the normal body, even in minute doses. An ade-
quate supply of vitamin A in the blood is necessary
to maintain the mucous membranes in a stage
of full physiological activity, including their
functions of preventing bacterial infections and
parasitic infestations, Vitamin D can be used
with advantage to increase the bactericidal power
of the blood and is of importance in connection
with calcium and phosphorous metabolism.
Vitamin E appears to be essential for normal
reproduction and lactation. It is found in the
unsaponofiable fraction of wheat-germ oil, and
shows close relationship to the group containing
Vitamins A and D.
Green [1938] has reviewed the importance of
trace elements in veterinary science. Many of
the obscure diseases have now been attributed to
the trace elements. Since plant food is the basis
of animal life, any trace elements present
in the plant are likely to be found in
traces in the animal body as well, where they
may exercise a beneficial effect (e.g., copper,
cobalt, manganese) or a harmful effect (e.g. fluorine,
selenium and molybdenum) or be entirely inert
(e.g. boron). ' Nutritional anaemias ' described
under various names in various countries were
considered to be due to iron deficiency and pre-
vention of the disease could be achieved by pro-
viding licks of crude iron compounds. But, it is-
now known that catalytic trace elements arc
frequently involved in the aetiology of these
naturally occurring conditions—sometimes copper,
sometimes cobalt and sometimes both apart from
ensuring sufficient iron for actual haemoglobin
formation. Stewart and Ponsford [1940] have
stated that although administration of cobalt has
failed to cure pining, the possibility is not ruled
out that specific deficiency of this element may
play an initial part in some areas in the cause of
pining by lowering resistance to parasitic diseases.
Manganese is now regarded as an essential trace
element for animal life, appears to stimulate
growth, is involved in haematopoietic function,
in skeletal metabolism and in reproduction. An
excess of fluorine in drinking water interferes with
bone metabolism and causes dental defects, osteo-
porosis, etc. An excess of selenium is manifested
in cattle, horses and swine by a depressed rate of
growth, loss of hair, most conspicuous in the mane
and tail of horses, abnormal development and
sloughing off of hoofs. Watson [1938] has
suggested that the scouring and reduced milk
yield of cows in certain seasons may be caused by a
higher content of molybdenum in herbage of certain
grazing areas of Somerset. Boron is known to be
essential for plant life and hence finds its way in
traces into the animal economy where, however,
there seems to be as yet no proof that it performs
any specific function. Traces of zinc, which seems
to function as a stimulant to the growth of certain
crops, increasing cholorophyll production and
photosynthetic activity etc., would naturally find
their way into the animal economy and are appa-
rently sufficient since no naturally occurring zinc
deficiency disease " has been reported, although
rats experimentally fed upon a purified diet
containing less than 0.02 mg. per day showed
delayed intestinal absorption and decrease in
growth rate.
Cuthbertson [1940], while discussing the quality
and quantity of protein in relation to human
health and disease, has stated that although the
adult physical pattern is determined by hereditary
influences, yet in the period of growth it may be
enhanced, dwarfed, warped, or mutilated by the
influence of the environment of which man's
food supply and its protein element form a part.
McCay [1912], quoted by Cuthbertson, states that
there is ample proof of the all-important influence
exerted by food and particularly protein, in de-
termining the degree of muscular development,
the general physical endowment, the powers of
endurance, resistance to disease, and most of all
the place a tribe or race has won for itself in manli-
ness, courage and soldierly instincts, etc. The
higher the level of protein interchange, the more
robust and energetic, and the more manly the
race. The density of population in relation to
available food supply determines the protein
intake. Low protein in diet reduces an
animal's resistance to disease and retards the heal-
ing of wounds and prolongs convalescence.
Du Toit et al. [1941] have concluded that since,
unlike phosphorus or calcium, the reserves of
which in the animal's body may tide it over a long
period of inadequate intake without appreciably
affecting its productive performance, protein
undernourishment-may immediately limit produc-
tion or prevent it entirely. The low level of this
constituent existing for several months in each
year in most natural pasturages must be
considered the limiting factor in the productivity
of both cattle and sheep in the Union of
South Africa. They have further stated that the ex-
treme deficiency of protein in the grass pastures
during winter is a problem of equal, if not greater
importance than that of phosphorus deficiency
and they surmize that the improvement or