121 Seekles: Trace Elements in Pastures and Animals 



vidual sensitiveness of the animals play a part? Although this 

 possibility should not be excluded, the regional occurrence of the 

 disorders, in certain years, does not make it Hkely. The possible 

 influence of the weather on the chemical composition of grass, 

 e.g., the amount of precipitation and the temperature should, of 

 course, be taken into consideration. Furthermore, farming meth- 

 ods, types of manuring, etc., should be considered as important 

 factors in causing the differences found in the clinical aspects of 

 the symptoms. During the war years, particularly, the manuring 

 of the pastures and the feeding of the animals left much to be 

 desired. This favours the assumption that the metabolism of 

 copper and other trace elements in plants and animals is influ- 

 enced by metabolic processes of other chemical components. 



The veterinarian is generally confronted by a disease which is 

 to be considered as the result of a number of effects caused by 

 a (conditioned) deficiency of trace elements in the normal course 

 of the biochemical processes involved. It is easily understood 

 that, as a result of these effects, some general symptoms, like de- 

 layed growth and interference with other vital functions, will be 

 observed. It goes without saying that this effect may not be 

 regarded as being caused only by a special deficiency, e.g., of 

 copper. It should be borne in mind that disorders of quite a 

 different nature, such as gastro-intestinal strongylosis and Johne's 

 disease, may cause similar symptoms. A thorough clinical, para- 

 sitological and bacteriological examination should, therefore, never 

 be omitted. 



It should be emphasized that, as a rule, scouring is a prevalent 

 clinical feature of "conditioned deficiency" of trace elements in 

 cattle. Evidence has been obtained that in many cases an in- 

 creased motility of the intestine may result in a decreased absorp- 

 tion of trace element and may be responsible, in this way, for the 

 low content in trace elements which the chemical analysis shows 

 in blood and tissues. 



An increased intestinal motility may originate from a number 

 of factors affecting the intestine, e.g., the intake of rank, young 

 pasture grass in spring, worm infestation (gastro-intestinal strongy- 

 losis), Johne's disease and other kinds of "enteritis." A special 

 influence of endogenous toxins, originating from gastro-intestinal 

 autointoxication, on different organs, resulting in a mobilization of 

 trace elements, stored in the tissues, also may not be excluded. 



