74 



TABLE 6-9. Mean tissue metallothionein 

 concentrations for rats supplemented with 

 different sources of Zn and Cu for 4 wks 

 and then depleted for 1 wk (fig MT/g a ) b . 



Sources Kidney Liver 



ZnS0 4 44 30 



ZnMet 3 7 32 



ZnLys 42 3 



CuO 43 32 



CuS0 4 4 3 3 



CuLys 39 27 



a (lg MT/g= \lg of Metallothionein per gram of wet 

 tissue . 



b SEM are as follows: kidney = 9, liver = 6, no 

 differences (P > .05) . 



Discussion 



Plasma Zn and Cu concentrations for phase 1 of the 

 experiment were very similar to those noted by Blalock et al . 

 (1988) when inorganic Zn and Cu supplementation was used at 

 different levels. Plasma Zn concentrations may have been 

 slightly high in our study because of limited hemolysis of a 

 few samples. The lower serum Cu concentration for animals 

 supplemented with CuO confirms the poor bioavailability of 

 this source (Kincaid, 1988) . Plasma Zn and Cu concentrations 

 decreased during the week of depletion. Following a similar 

 pattern, CuLys supplemented rats had higher plasma Cu 

 concentration than CuO supplemented rats but this time CuO was 

 not different than CuS0 4 which could suggest a higher 

 retention for CuLys. 



