PREVENTION OF DISEASE.

Otago Daily Times, Issue 21244, 27 January 1931, Page 4

PREVENTION OF DISEASE.

LACK OF BALANCED DIET. ANIMALS’ NEED OF MINERALS. One of the limiting factors in the increase of production from our grass lands is the prevalence of disease among our flocks and herds. A study of pamphlets dealing with research on live stock diseases which have been published by the research institutes at Home, has led the writer to the conclusion that the prevalence of animal diseases to-day is due more to a lack of vitality in the stock than to an increase in the microorganisms causing disease. This may be hard. to believe, since breeding for strengthened constitution has made rapid strides in the last half-century, but is borne out by Dr J. B. Orr, director of the Rowett Research Institute a contributor to the New Zealand Herald). Dr Orr says: “It is believed that in the case of many diseases due to invasion of micro-organisms, the condition of the animal itself is an important factor in determining whether the disease will develop, and, that even if it does develop, the condition, of the animal will have an influence" on the degree of severity of the attack. If this view, which has a great deal of evidence to support it, be correct, deficiencies in pastures would tend to predispose the grazing anim'al to a number of diseases, in addition to the specific pathological conditions directly due to the deficiency.” In other words, the animal which is confined in comparatively narrow limits soon exhausts the soil of the essential minerals and the pastures of the particular varieties of herbage which would keep it in condition, and it thereafter is in a lower state of health, and more subject to the attacks of disease which its system cannot throw off. EXHAUSTION OF MINERALS. Those minerals which are most likely to become exhausted from the soil by the continued export of animal products are calcium, phosphoric acid, iron chlorine, sodium, and iodine. All of these are readily soluble in water, and hence in open-type soils are frequently leached into the sub-soil and are thus beyond the reach of plant roots. What minerals were originally available to the plants have been consumed by the grazing stock and sent overseas as wool, meat, bone, butter, and cheese. Present-day research appears to be directed chiefly toward finding cures for diseases, which have already become established, whereas a more commonsence procedure would appear to be the attacking of the problems by searching for a means of preventing the disease becoming established. There is no doubt in the writer’s mind that an ample and regular supply of the minerals required by livestock will go a long way toward preventing even the most serious diseases. It seems, no doubt, a somewhat bold claim that a properly-compounded mineral lick will prevent abortion, sterility, mammitis, milk-fever, and, perhaps even footrot in sheep. Nevertheless, experiment has shown that each of these

troubles has been considerably lessened and in some cases completed overcome, when minerals in an available form have been fed regularly. PERSEVERANCE NECESSARY. Neither prevention nor cure is effected by feeding minerals for a month or two and then discontinuing because results are not immediately noticeable. The animal has to develop its resistance to disease slowly. With a year of mineral feeding considerable improvements will be noticed. In the course of two years disease will be come rare, and a continuance of mineral feeding will result in entire freedom from disease. It is not sufficient, however, to supply minerals in raw form to animals and expect them to be assimilated. Nature has arranged a much more complicated system which we must imitate as far as possible. Nature provides soil bacteria and soil acids to break down and make soluble the raw minerals so that the plants can absorb them. The mineral-bearing soil water is taken up to the leaves, where it is digested and mixed with various elements extracted from the air and acted upon by the sunlight. It then becomes sap, from which the plant builds up new tissue. This, in turn, is suitable for food for herbivorous animals, which can absorb and utilise the minerals presented to them in this organic form. ASSIMILATION OF MINERALS. Experiments have proved that animals can assimilate about 5 per cent, of inorganic minerals, the remaining 95 per cent, acting as irritants to the digestive organs. When, however, these same minerals are given to the animals in an organic form, they can assimilate up to 95 per cent.,, with no resultant irritation of the stomach or other organs. Salt is one of the few inorganic minerals which both animals and man can assimilate in quantity without harm, and it is appreciated as a base with which to incorporate other minerals. Lime and phosphate should always be given in organic form where possible, and both these will be found in bone, whichj when finely powdered, as in bone flour, is practically all assimilable. Experiments are now being conducted to discover an organic form in which iron can be administered. Meanwhile, either as ferrous oxide (ordinary oxide of iron) or as sulphate of. iron, it has been found to have good effect if not given in too large a quantity. lodine, though very essential as a stimulant of the important thyroid gland, is required only in very minute quantities and as this is a fairly expensive ingredient, it is well to remember that not more than half an ounce per 1001 b of lick is desirable, though it cannot be omitted altogether.