Report of Dept. of Agric. Union of S. Africa.
HUTCHEON'S inquines into the nature of this disease in 1895 led him to form the opinion that it was due in some way to a deficiency of phosphates in the diet. An experiment designed to test this view certainly gave it considerable support.
A further carefully controlled series of experiments carried out in. 1907 lent additional support to this view. In both these sets of experiments the administration of bone meal appeared to have a remarkable effect in preventing the disease.
Two years later another experiment on the same lines also furnished confirmatory evidence that the view put forward was correct, but in this case so much reliance could not be placed upon the experimental results, as it was shown that some of the animáis died from a disease other than lamziekte, namely heart water.
Between 1904 and 1910 three or four reports were published regarding the pathology of the disease, in which support was given to the view that the cause of the condition was an organism of the fowl cholera type.
An experiment carried out in 1908 by the Government Veterinary Bacteriologist for the Transvaal yielded negative results, as none of the animáis died, but during the course of these experiments the fact was established that stijfziekte and lamziekte, regarding the identity of which there had been some doubt, were in reality two different conditions and, further, that the former of these was due to the cattle eating Crotalaria burkeana.
In 1909 a further series of experiments was carried out, but again the results were inconclusive as only one control animal died.
Experiments were again undertaken in 1911. Fifty animals were allowed to graze night and day upon the veldt, and fifty others were herded with them, but these were muzzled during the day and fed in a kraal at night with forage from a clean area. Of those at liberty on the veldt 28 per cent, became affected and only four animals recovered.
All attempts to transmit the disease with materials derived from dead animals failed.
No cases of lamziekte were produced in experiments in which animals were fed with 57 species of plants.
Grass cut from the land where the grazing cattle had contracted the disease failed to produce any cases when fed to cattle in clean areas. It was further found that the disease tends to disappear when an infected area has been well grazed down.
Experiments to test the view that the disease might be due to lack of vitamines failed to produce any evidence to this effect.
It was found that a certain degree of immunity was established by the inoculation of susceptible animals with blood derived from cases of the disease and also with cultures of the organism of the fowl cholera type which had been blamed as the cause of the disease. This immunity, however, did not appear to be specific.
The general conclusions arrived at are as follows: -
The disease is primarily one of the muscular system, the nervous system being involved secondarily. The toxin which is responsible for the disease of the muscular system is not necessarily cumulative in action, as cases may occur in as short a period as fifteen days after exposure. The toxin is in some way connected with the feeding of grass, but whether the grass as such or something taken in with the grass is responsible cannot yet be determined. The failure to set up the disease with grass or hay from a lamziekte area tends to support the latter view. The fact that in one of the experiments in which the animáis were muzzled two contracted the disease ten and twelve days after they had ceased grazing may possibly indicate a period of incubation.
Record Number :
Language of text :
Language of summary :