It has long been recognised that minerals play an important part in animal nutrition. We in New South Wales are well aware of the ill-effects produced by the pasturage of stock on mineral deficient soils and have had experience with such a condition as bone-chewing disease of cattle, which it is now agreed is due to the lack of phosphorus in the diet. With pigs, too, we know that paralysis of the hindquarters is associated with an imbalance of time and phosphorus in the food in these cases the diseases caused are due to the lack of quite appreciable amounts of the minereis concerned.
Recent work, however, has shown us that many other minerals play an important part in the economy of the animal body, and that very slight quantities of these minerals are necessary to good health. The deficiency, however, of these minerals may be the cause of ill- health and death.
Probably the best known example of this type of disease is the "Bush Sickness of New Zealand." Bush Sickness occurs on country of volcanic origin and the pasturage looks rich and succulent. Yet, in spite of the attractive appearance of the grasses and clover, the stock grazed thereon lose condition and become poor and anaemic. The first work carried out suggested that the condition was due to a deficiency of iron, and after certain investigations, it was found that a native iron oxide, known as "limonite," would prevent the disease. Later, the work into similar diseases carried out by Marston and Lines in South Australia, and Filmer and Underwood in Western Australia, suggested that the iron in the limonite was not the curative factor but cobalt, which existed as an impurity in the iron ore. It is now accepted that Bush Sickness is due to a lack of cobalt in the diet and the administration of a tiny amount of cobalt daily in the food will prevent the disease.
West Australian veterinarians have carried out investigations into two diseases of stock and in both cases found that the ill-health was due to the deficiency of small amounts of mineral in the pastures. These were Denmark Disease (Enzootic Marasmus) of cattle and Enzootic Ataxia of sheep.
Denmark Disease was so called because it occurs in the Denmark district. Cattle pastured on this area developed a slowly progressive wasting disease although the pastures appeared satisfactory to naked eye examination. Affected stock removed to other districts rapidly recovered. Filmer of West Australia, formed the opinion that the disease appeared similar to the Bush Sickness of New Zealand and found, as the workers in that country had done, that the condition could be cured by the administration of iron compounds. He, however, thought that the iron itself might not be the curative factor and found that the animals recovered when an iron-free extract of limonite was administered. Underwood was associated with Filmer on the chemical side of the investigation. At first the two investigators thought that nickel might be the mineral which cured the condition, but later they tried the effect of cobalt and found that the administration of this mineral gave successful results. The work indicates that the Enzootic Marasmus of West Australia is due to cobalt deficiency.
Enzootic Ataxia or Gin Gin Disease, has been recognised as a cause of loss in lambs in West Australia for many years. The affected lambs are unthrifty, stunted in growth and show inco-ordination of movement. If the ewes are pastured on sound country whilst pregnant they will give birth to normal lambs, but if maintained on the affected country they become anaemic and lambs become sick within six weeks or more of birth. Experimental work by Bennetts and Chapman has shown that the disease is due to copper deficiency and that it may be prevented by the administration of copper during the gestation and nursing period.
Coast Disease of South Australia. This is a condition which occurs on certain coastal districts of South Australia when the soil is made up largely of shell fragments. The disease is characterised by loss of condition, anaemia and death. Experimental work was carried out for a long period before it was decided that lack of both cobalt and copper were responsible for the condition.
These brief notes indicate that mortalities and sickness in stock can be caused by the deficiency of the diet in minerals, traces only of which are essential to the correct performance of body functions. Cobalt and copper have so far been incriminated in this respect. The part played by copper in the body metabolism has assumed considerable importance during the past few years. Not only has lack of copper in the food been incriminated as a cause of disease, but it is considered that copper is necessary for the proper assimilation of iron whilst excess copper in the food may lead to chronic copper poisoning, the chief symptom of which is jaundice.