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the cause of abnormal conditions in sheep and
cattle. By the middle of last century it was
proved that some of these conditions in cattle,
occurring in certain districts in Europe, and es
pecially in the winter months and in seasons of
drought, were due to the lack of either lime or
phosphorus in the pasture or fodder.
In parts of South Africa, Australia and the
United States lack of phosphorus in the pasture
is associated with a disease which goes by various
names, but is. characterized during the life of the
animal by stiffness of gait, slow growth, poor
breeding capacity, general unthriftiness and pica
(i.e., a ' depraved ' appetite for substances such
as old bones or earth) and on post-mortem examina
tion, by a soft or brittle condition of the bones.
It has been shown, under experimental condi
tions, that lack of lime in the rations of cows may
be the cause of failure to breed successfully, the
calves being either born dead or with such low
vitality that the death rate is high. Lack of
sodium and chlorine has been proved to be a
cause of unthriftiness in milk cows. Iron and
iodine are also needed by the animal, but only in
traces.
It is believed, however, that deficiencies, less
marked than those referred to above as the
direct cause of certain abnormal conditions, may
exist and be the cause of a degree of malnutrition
which affects the rate of growth and production,
and may possibly render the animals more sus
ceptible to specific diseases. Orr [1930] has
suggested that in order to balance up the rations
with minerals one should calculate from the known
composition of the carcasses of animals or of
products such as milk, the amounts of each of the
different minerals which must be absorbed from the
intestine and retained in the body for the building
up of the bones and other tissues in growth, or
used for the elaboration of products such as milk.
For example, calcium (calculated as CaO) is
present in the bodies of cattle to the extent of
about 2 per cent and the percentage of phosphorus
(calculated as P 2 O 5 ) is only slightly less. Therefore,
young cattle putting on 2 lb. per day live P 2 O 5
weight would need to absorb and retain more than
½ oz. of lime per day. Every gallon of milk con
tains about ¼ oz. of lime and ⅓ oz. of phosphoric
acid; hence a cow giving four gallons of milk a
day would lose each day about 1 oz. of the former
and 1⅓ oz. of the latter in the milk. Only part
of what is contained in the food is absorbed from
the intestine and even what is absorbed is not all
available for formation of new tissue or for milk,
because there is a continuous, loss through ex
cretion. Hence, the food must contain more than
is required to be retained in the body or secreted
in the milk. To make up for calcium and phos
phorus deficiencies, ground limestone and steriliz
ed bone meal may be used respectively. Eraser
[1935] has stated that wild herbivora and native
breeds of cattle seem to be less liable to the effects
of mineral deficiency than imported breeds of high
fertility, rapid growth and heavy milking type,
because such functions require more phosphorus
than the natural pastures of a large area of the
world can supply and therefore the improved
breeds may die, lose type or revert to scrub under
less favourable conditions. Progressive deple
tion of minerals in pasture lands exerts quite an
apparent influence on the general well-being of
the stock resulting in conditions like osteophagia,
delayed maturity, etc. He has suggested that the.
mineral deficiency can be combated by supplying
the deficient mineral element in adequate amount
either by direct feeding or indirectly through crop
by manuring the soil, the latter appearing
theoretically a more natural method.
Recently du Toit, Louw and Malan [1941] have
published their final report on a study of the
mineral content and feeding value of natural
pastures in the Union of South Africa. In this
study, originally it was decided to analyse the soil
from selected areas, the herbage growing on the
soil and the blood of cattle grazing on the pastu
rage. It was thought that a definite correlation
existed between these three sets of data. But
after the first three surveys which were reported
on separately by du Toit et al [1932], the collection
of soil samples was discontinued. The results
warranted the conclusion that soil analysis does
not provide a satisfactory method for studying
the feeding value of natural pastures, as pasture
on poor soil may yield excellent values if the sam
ples for analysis are taken at an early stage of
growth of the pasture. ' Animal ' samples of
natural pasturage were collected and chemically
analysed. These samples were collected by follow
ing the animals at pasture in order to ensure that
such samples were as closely as possible representa
tive of what the animals actually consumed on the
day of collection. Judged by the estimated
requirements of cattle and sheep for growth
all South African natural pastures, composed
mainly or wholly of grasses are deficient in phos
phorus, crude protein and in certain areas, sodium
for a period ranging from five to nine month of the
year, depending on the area. There are indications
that in certain of those regions the pasture may be
deficient in phosphorus also throughout the year.
Furthermore, on the basis of the average value for
phosphorus, these grass pastures contain at no
time of the year sufficient of this nutrient to pro
vide in the requirement for an additional function
(e.g., gestation or lactation) of the animal, super
imposed on growth. Theiler [1934] described in
detail the clinical and histopathological features of
the skeletal diseases of animals caused by mineral