Rothamsted Symposium on Trace Elements 122 



We observed, in any case, a significant difference between the 

 copper content of the liver in 10 typical cases of gastro-intestinal 

 disorders, of different origin, and in 55 normal cattle livers. The 

 basis, respectively. In 10 cases, originating from a typical scour- 

 ing area on peat soil, an average value of 16.6 mg of copper was 

 observed, probably indicating a decrease of copper content. Five 

 of the cases observed were calves which, as a rule, showed a 

 higher copper content of the liver than adult animals. 



The veterinarian, as a rule, will not be able to distinguish the 

 above mentioned partial effects. This results in a certain vague- 

 ness in making the diagnosis and uncertainty in therapeutic plan- 

 ning. 



The experience of recent years has shown that the veterinar- 

 ian—and less so, naturally, the breeder or agricultural expert— is 

 not able to arrive, as a rule, on the basis of his observations, at a 

 definite diagnosis of (conditioned) deficiency in trace elements. 

 To do this, with a reasonable chance of success, he needs the 

 assistance of a chemist who will help him with the analysis of the 

 food, the blood and the tissues of the animal. 



So far, mainly the composition of pastures and the symptoms 

 of disease in plants and in herbivorous animals have drawn our 

 attention to the study of the functions of trace elements. This 

 type of research will always be of the utmost value. For our 

 knowledge of the origin of the disorders in plants and in animals, 

 resulting from a relative deficiency or excess of trace elements, 

 further research is required into the symptoms appearing between 

 the absorption of the food and the moment in which pathological 

 disorders in plants or animals begin to show. The study of the 

 origin of these disorders is the task of the biochemist as the 

 processes of intermediate metabolism are of a biochemical nature. 

 Only a thorough biochemical examination of the consecutive 

 reactions in cells, tissues and organs will lead to rational diagnos- 

 tics and an effective fight against the diseases concerned. 



For a number of years, in the Laboratory for Veterinary Bio- 

 chemistry of the University of Utrecht research has been con- 

 ducted on the occurrence of trace elements— especially copper, 

 cobalt, manganese, molybdenum and selenium— in pasture grass, 

 blood and liver of cows and horses. The results are based on the 

 clinical and chemical examination of several hundreds of diseased 



