M.—AGRICULTURE. 211 
adjustment of the ration by the addition of salts present in too small 
amounts has resulted in a rather greater yield of milk and in an increase 
in breeding capacity and decrease in disease. The number of such pro- 
longed feeding experiments with dairy cows is, however, not sufficient 
to enable conclusions with regard to the value of the mineral additions 
to be drawn with the same degree of certainty as in the case of pigs or 
poultry. 
In recent experiments with hand-fed sheep, it has been found that the 
adjustment of a ration of turnips, straw and cereal grains, by the addition 
of calcium and chlorine, which are deficient, increases the rate of growth 
_and improves the quality of the fleece. A striking example of the im- 
portance of mineral salts in the diet of sheep comes from Michigan, 
where, owing to high mortality, the sheep industry suffered seriously. 
_ The feeding of mineral salts found in deposits near the Great Lakes was 
_ followed by the disappearance of the trouble. 
Some interesting cases of deficiencies of one or more minerals in natural 
pastures have been discovered. In an investigation being carried on 
partly at the Rowett Institute and partly at the Nutrition Institute at 
Cambridge, it has been found that there are marked differences in the 
mineral content of uncultivated pastures grown in different localities, 
and that there appears to be a correlation between the mineral content 
of the pasture and its feeding value, as determined by the number of stock 
it can carry, and the health and breeding capacity of the stock. An 
- interesting fact brought out is that, where the sheep have a choice of 
_ pastures, they actually eat the herbage the mineral composition of which 
‘most closely approximates to that of good cultivated pasture. As we saw 
above, good pasture contains the various elements in proportions somewhat 
similar to those which are found in milk and might therefore be presumed 
to be suitable for growth and the maintenance of health, as indeed is 
found to be the case in practice. 
__ In various countries where the modern type of rapidly growing animal 
has been put to graze on uncultivated pastures, malnutrition, as shown 
by stunted growth, low milk yield, or increased liability to disease, has 
appeared. Thus, in South Africa Sir Arnold Theiler and his associates 
have shown that deficiency of phosphorus in the pastures is the cause of pica 
(depraved appetite), which is prevalent in cattle in certain districts there 
which leads to the ingestion of the organism which causes lamziekte, 
_that the condition can be prevented by feeding bone-meal, or any 
dstuff rich in phosphorus. Not only does this adjustment of the mineral 
intake prevent the disease, but the general condition of the animals is 
improved. 
__ The two elements most frequently deficient in pasture are probably 
cium and phosphorus. Malnutrition due to deficiency of these has been 
ed in various districts in Australia, New Zealand and India, and in the 
kland Islands. Other minerals may, however, also be deficient. 
us, in the North Island, New Zealand, Aston has found that deficiency of 
is the cause of malnutrition in animals which are grazed continuously 
ertain areas. The condition is avoided if the animals are transferred 
time to an area where the pasture is richer iniron. The symptoms 
the disease can be relieved by feeding iron salts. It is probable that a 
ar condition occurs in parts of the Cheviots where soil conditions are 
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