139 Seekles: Trace Elements in Pastures and Animals 



ility, due to manganese deficiency in cattle, may well be expected 

 in clay areas with a high fH. No relation could be established 

 between the occurrence of grass tetany in cattle and the manga- 

 nese content of pastures. 



3) Trace elements act as bio-catalyzers of enzyme action 

 in fundamental processes of intermediate metabolism. This ac- 

 counts for the great variety of clinical symptoms in diseases due 

 to a deficiency of trace elements. 



4) In many cases scouring is a prevalent symptom. Increased 

 motility of the intestine results in a decreased absorption of trace 

 elements and it may well be essential in originating the low con- 

 tent of trace elements in blood and tissues (liver). An increased 

 intestinal motility may result from different chemical and micro- 

 biological factors affecting the intestine. 



5) As a rule, cattle liver shows a low saturation with regard 

 to copper and a wide variety in the copper content. In horse 

 livers there is less variation of copper content and the average 

 copper content is higher. 



6) In a three weeks balance trial with a heifer, about 17 per 

 cent of the copper sulfate added to the food was retained in the 

 body. Radioactive copper, intravenously injected into calves, was 

 stored in the liver to a considerable extent, e.g., up to 24.5% of 

 the quantity injected over VA hours. Evidence has been ob- 

 tained that copper, intravenously injected in horses, is, in the same 

 way, rapidly transferred to the tissues. 



7) So far no evidence has been obtained that selenium and 

 molybdenum play a part in farm animal diseases in the Nether- 

 lands. 



I should like to acknowledge the assistance received from my co-workers 

 Dr. R. BijKERK, Professor E. Havinga, Mr. S. T. Hofstra, Dr. J. T. L. B. 

 Rameau, and Dr. J. de Wael. We are indebted to Mr. H. Hooghoudt 

 and Mr. J. P. L. Kranendonk, our technical assistants. 



