127 Seekles: Trace Elements in Pastures and Animals 



per kg of dry matter and about 40 per cent contained more 

 copper, up to 194 mg per kg of liver for a bull (only one case) 

 and 91 mg for a cow. 



It appears that in 60 per cent of the cases examined the extent 

 of saturation of the liver is likely to be rather low. This may 

 account for the relative stability of the copper content of the blood 

 after an oral administration of copper sulfate. 



Another series of experiments gives further information con- 

 cerning the absorption of copper by the liver following intravenous 

 administration. In these experiments we used radioactive cop- 

 per salts (5). 



Table 23 : Copper content (mg per kg of dry matter') of 55 samples of liver 

 originating from normal female cattle (in collaboration with R. BijkerK): — 



• One sample originated from a calf {\i years of age), 

 ■f Sample originated from a bull. 



Three copper salts— copper acetate, copper glycinate and the 

 sodium salt of copper allylthioureabenzoic acid ("Ebesal)"— were 

 injected (calves, weight about 30 kg). The copper salts had been 

 irradiated by a neutron generator (Ra-Be preparation) for 24 

 hours or more. The radioactivity of the copper acquired— meas- 

 ured by means of a sensitive Geiger-Miiller counter— enabled us 

 to measure the rate of absorption of the various copper salts by the 

 liver. 



The relatively slight radiation of the copper salts and the 

 rather short half life (13h) of the radioactive copper isotope made 

 it necessary to inject as large quantities as could be tolerated by 

 our animals. 



Table 24 presents the results. 



Evidently, there is a parallelism between the "solidity" of the 

 copper compound used for injection and the rate of its absorption 

 by the liver. 



The difference between Cu-acetate and Cu-glycinate is only 

 slight. In both cases, copper is almost equally absorbed by com- 



