137 Seekles: Trace Elements in Pastures and Animals 



ing water and soil from farms where cattle showed severe symp- 

 toms of shedding of hair and acetonemia. In all cases examined 

 no excess selenium was found. 



Discussion:— The great variety of clinical symptoms observed, 

 in cases of real and conditional deficiency or in cases of an excess 

 of trace elements, may easily be understood, if we assume a va- 

 riety of action on different enzyme systems involved in the major- 

 ity of processes of intermediate metabolism. The veterinarians 

 and breeders are mostly confronted with diseases which are to be 

 considered as a result of a number of partial effects in the normal 

 biochemical processes in the animal body. As a result of these 

 effects certain symptoms, like stunted growth and interference in 

 other vital functions, will generally be observed. As a rule, these 

 effects may not be regarded as inherent to a special deficiency or 

 to an excess of a special trace element. 



In many cases of "conditioned deficiency" of trace elements 

 scouring is a prevalent feature. Evidence has been obtained that 

 often increased motility of the intestine may result in a decreased 

 absorption of trace elements and in this way may be responsible 

 for the low content in trace elements as, e.g., the small amounts 

 of copper found in the blood and in the tissues (liver). Increased 

 intestinal motility may originate from other factors affecting the 

 intestine regardless of the trace elements in food, e.g., the intake 

 of proteins and other constituents of rank, young pasture grass in 

 spring and as a result we note worm infestation (gastro-intestinal 

 strongylosis), Johne's disease and other kinds of "enteritis." 



In catde, the copper content of the liver was shown to vary 

 between 5 and 194 mg per kg (dry matter basis). In 62 per cent 

 of the cases observed, the copper content did not exceed 5-15 mg 

 indicating a low saturation of the liver. This may account 

 for the relative stability of the copper content of the blood follow- 

 ing a daily administration of copper sulfate by mouth to a heifer 

 for a period of three weeks. In this balance trial about 1.6 g of 

 copper, i.e., about 17 per cent of the copper added to the food, was 

 retained in the tissues. That the liver is of prime importance 

 with regard to the accumulation of copper is shown by experi- 

 ments in which radioactive copper salts were intravenously ad- 

 ministered to calves. 



In horses, the copper content of the blood serum is somewhat 

 higher than in catde. Several intravenous injections of copper 



